Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Existing Conditions Report. February 2017

Transcription

1 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Existing Conditions Report February 2017

2 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Executive Summary... ES-1 1 Background Introduction Objectives for Biosolids Management Purpose of Plan Existing Conditions Overall Process Description Current Solids Loadings...2 Influent Flow...2 Influent Total Suspended Solids and Biochemical Oxygen Demand...4 Primary Sludge...5 Waste Activated Sludge...7 Sludge Thickening...8 Sludge Digestion Sludge Dewatering Biogas Production Existing Solids Handling Facilities Introduction Gravity Thickeners Primary Digesters Secondary Digesters Dewatering Facilities Boiler Building Cogeneration Facility Gas Collection and Storage Sludge Storage Facilities Biosolids Projections Design/Future Biosolids Projections Proposed Hauled Waste Projections Biogas Utilization Biosolids Technology Assessment Sludge Thickening Gravity Belt Thickener (GBT) Dissolved Air Flotation (DAF) Thickener Centrifuge Rotary Drum Thickener Volute Thickener Table of Contents i N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

3 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water WAS Thickening Recommendations Hauled Waste Handling Anaerobic Digestion Dewatering Centrifuge Screw Press and Volute Dewatering Press Rotary Press Vivianite Control Biogas Utilization Assessment Expected Energy Potential from Biogas Heating Requirements for Digestion and Building Heating Biogas Utilization Technology Assessment Fuel Cells Reciprocating Engines Biogas Pretreatment Natural Gas Pipeline Injection Future Regulatory Trends Standards Pollutants Pathogen Reduction Vector Attraction Reduction Biosolids Management General Permit Land Application 30-Day Notice Recordkeeping Land Application Requirements Regulatory and Non-Regulatory Drivers Phosphorus Management Hauled Waste Acceptance Odor Farmland Availability and Demand for Product Summary of Improvement Plan Biosolids Facility Overall Improvements Separately Thicken Waste Activated Sludge and Primary Sludge Increase Utilization of the Existing Anaerobic Digesters Combined Heat and Power Generation Anaerobic Digestion Improvements Table of Contents ii N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

4 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 6.2 Specific Facility Recommended Improvements Gravity Thickener Facilities Hauled Waste Facility Waste Activated Sludge Thickening Facility Sludge Blending Tank Primary Digesters and Control House Secondary Digesters and Control House Dewatering Facilities Boiler Building Cogeneration Building Vivianite Management Sludge Storage Sheds Gas Collection, Storage and Pretreatment Improvements Phasing and Cost Analysis Age and Condition of Existing Processes Maintain Biosolids Facilities in Service Availability of Funding in Relation to Other Infrastructure Needs Analysis of Hauled Waste Alternatives Alternative 1 - Hauled Waste Base Case Alternative 2-30% Hauled Waste Alternative 3 - No Hauled Waste Hauled Waste Cost Analysis Parameters and Assumptions Net Present Value Risks to the Hauled Waste Alternatives Sensitivity Analysis Other Biosolids Improvement Plan Benefits Hauled Waste Recommendation Summary and Cost of Improvements Biosolids Facilities Improvements Phasing Plan Table of Contents iii N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

5 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water List of Figures Figure ES-1. Schematic of Recommended Biosolids Improvements... ES-4 Figure ES-2. Biosolids Facilities Improvement Phasing Plan... ES-7 Figure 2-1. Existing Solids Process Flow Diagram...2 Figure 2-2. Daily Influent Flow...3 Figure 2-3 Average Monthly Influent Flow...3 Figure 2-4. Average Monthly Influent BOD5 and TSS Concentration...4 Figure 2-5. Average Monthly Influent BOD5 and TSS Loads...5 Figure 2-6. Daily Primary Sludge Flow...6 Figure 2-7. Daily Primary Sludge Total Solids Load...6 Figure 2-8. Daily Waste Activated Sludge Flow...7 Figure 2-9. Daily Waste Activated Sludge Total Solids Load...8 Figure Daily Thickener Underflow...9 Figure Average Monthly Thickener Underflow Total Solids Load...9 Figure Average Monthly Primary Digester Solids Load Figure Average Monthly Primary Digester Volatile Solids Load Figure Average Monthly Belt Folter Press Dry Cake Load Figure Average Monthly Primary Digester Gas Production Figure Monthly Gas Usage: January 2014 July Figure 4-1. Schematic of Two Phase Anaerobic Digestion Figure 4-2. Cutaway View of Biosolids Dewatering Centrifuge Figure 4-3. Screw Press Figure 4-4. Volute Dewatering Press Figure 4-5. Six Channel Rotary Press Figure 4-6. Schematic of CHP Option for Biogas Utilization Figure 4-7. Schematic of Natural Gas Injection Option for Biogas Utilization Figure 6-1. Schematic of Recommended Biosolids Improvements Drawing Drawing Drawing Figure 6-2. Proposed Storage Shed Figure 7-1. Phasing Implementation List of Figures iv N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

6 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water List of Tables Table ES-1. Solids Digestion Capacity... ES-3 Table ES-2. Hauled Waste Alternatives Cost Analysis... ES-4 Table ES-3. Recommended Biosolids Facilities... ES-5 Table ES-4. Project Cost Estimates... ES-6 Table 2-1. Digester Performance Summary Table 2-2. Existing Total Boiler Data Table 2-3. Existing Total Enginator Data Table 3-1. Sludge Design Criteria (AWTF) Table 3-2. Solids Digestion Capacity Table 3-3. VSS Loadings from Selected HSW Generators Table 3-4. Ratio of HSW to AWTF Solids at Selected Loadings Table 3-5. Current Biogas Generation with New CHP System Table 3-6. CHP: Future Conditions Table 4-1. Typical Design Criteria for Gravity Thickeners Table 4-2. Projected Gas Generation at Facilities Plan Digester Theoretical Design Capacity Table 4-3. Lean Burn Reciprocating Engine Values Table 5-1. Biosolids Pollutant Concentrations Limits Table 5-2. CRW 2015 Pollutant Analyses Summary Table 5-3. AWTF Historical Pathogen Reduction Monitoring Summary Table 5-4. CRW Historical Vector Attraction Reduction Monitoring Summary Table 6-1. Recommended Improvements by Facility Table 6-2. Hauled Waste Receiving Station Table 6-3. Gravity Belt Thickeners Table 6-4. Sludge Blending Tank Table 6-5. Acid Phase Digester Table 6-6. Secondary Digesters Table 6-7. Proposed Storage Shed Table 7-1. Incremental Capital for Hauled Waste Alternatives Table 7-2. Hauled Waste Alternatives Cost Analysis Table 7-3. NPV for Hauled Waste Alternatives Table 7-4 Summary of Improvements Table 7-5. Project Cost Estimates List of Tables v N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

7 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Executive Summary Overview Capital Region Water (CRW) owns and operates the Harrisburg Advanced Wastewater Treatment Facility (AWTF), permitted for a maximum month flow of 37.7 million gallons a day (MGD). A recent upgrade of the liquid treatment process to provide biological nutrient removal (BNR) levels of treatment was brought online in April The solids handling and treatment facilities were not upgraded as part of that contract. A team led by Whitman, Requardt & Associates, LLP (WRA) has evaluated the biosolids facilities at the AWTF and developed a plan that allows CRW to meet their goals and objectives for these facilities. This Biosolids Facility Improvement Plan provides the long-term planning for the AWTF biosolids facilities and outlines recommended facility improvements. The Biosolids Facility Improvement Plan is presented in seven sections: 1.) Background 2.) Existing Conditions 3.) Biosolids Projections 4.) Biosolids Technology Assessment 5.) Future Regulatory Trends 6.) Summary of Improvement Plan 7.) Improvements Phasing and Cost Analysis The Background section provides an overview of the Improvement Plan including the objectives for biosolids management and the purpose of the plan. The Existing Conditions section reviews the historical and current solids handling facilities and operation. The Biosolids Projections section establishes the expected biosolids generation for the 25-year planning period. Alternatives for biosolids operations and equipment are presented in the Biosolids Technology Assessment section. The advantages and disadvantages are considered in the context of making the best use of existing infrastructure and attainment of the biosolids management goals. The expectations for future biosolids regulation are included in the Future Regulatory Trends section. The Summary of Improvement Plan section summarizes the improvements for each biosolids facility. The Improvements Phasing and Cost Analysis section includes a phasing plan and cost estimates for each improvement. Condition Assessment Prior to the development of the Biosolids Facility Improvement Plan, WRA completed a condition assessment of the existing biosolids facilities. Existing biosolids facilities include: Two (2) Gravity Thickeners Two (2) Fixed Cover Primary Anaerobic Digesters Two (2) Secondary Anaerobic Digesters, one with fixed cover and one with floating cover Two (2) 2.5 Meter Belt Filter Presses Covered Biosolids Storage One (1) Gas Storage Tank Two (2) Biogas Driven 400 kw Internal Combustion Engine Driven Generators Three (3) Concentric Tube Heat Exchangers Two (2) Biogas Fueled Hot Water Boilers Polymer feed systems, pumps, piping and conveyance systems to support the operations. Executive Summary ES-1 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

8 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The condition assessment found many of the biosolids facilities to be operating well beyond their expected useful life, and some are not operating as intended. In general, the biosolids facilities are in need of extensive upgrades of the existing process equipment and supporting facilities. Additionally, there are potential opportunities to improve the energy efficiency and resource recovery from the solids and biogas utilization processes. Summary of Evaluations Through improvements to the solids treatment processes, additional biogas could be generated, and the associated energy recovered. Biogas is the methane rich gas produced during the anaerobic digestion of organics, and is a valuable resource produced by the AWTF. To capitalize on this resource, two areas must be addressed: Maximize the biogas production efficiency Optimize the energy recovery process The AWTF has been utilizing the biogas generated in the digester to produce electric power and generate heat. To increase the total energy recovered from the electric power generation process, the existing separate heat and power system is recommended to be replaced by a combined heat and power (CHP) system. By utilizing an efficient CHP system, the waste heat from the electrical energy generation process can provide the majority of the heat required for heating the digesters, at a relatively low operational cost. There are several opportunities to improve the biogas production efficiency (volume of biogas generated for each pound of organics fed to the digester) of the primary digesters including: Increase the percent solids of the sludge sent to the digester Improve digester mixing Improve digester operation, including maintaining a near constant temperature Co-digest high strength hauled waste from outside sources The proposed primary digester improvements that are currently being implemented at the AWTF will include new mechanical linear motion mixing, replacement of recirculation and transfer pumps, a new electrical and controls building, and replacement of sludge piping and valves, which will result in sludge heating improvements. These improvements will increase mixing efficiency and temperature control in the digesters, allowing for the digesters to accept a higher concentration of feed sludge. To increase the percent solids of the thickened sludge, it is recommended that the primary sludge and waste activated sludge (WAS) be separately thickened. To accomplish this, the primary sludge will continue to be thickened in the existing gravity thickeners. WAS will be thickened using gravity belt thickeners (GBTs). The two thickened sludges will be combined prior to entering the digesters. The GBTs will be installed in a new two story building adjacent to the existing primary clarifiers. A thickened WAS storage tank will be constructed adjacent to the new building. The primary digesters will have excess capacity over that needed to digest the sludge generated by the AWTF. Table ES-1 includes the capacity of the two (2) digesters after the ongoing refurbishment, the projected amount of sludge generated by the AWTF, and the resulting available digester capacity, that could be available for accepting outside high strength wastes (referred to hauled waste ). Executive Summary ES-2 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

9 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table ES-1. Solids Digestion Capacity After Primary Digester Upgrades and Before WAS Thickening After WAS Thickening Condition VS Loading (lbs / day) VS Loading (lbs / day) Digester Capacity 37,000 61,000 Projected Loading from AWTF 24, ,560 2 Available Capacity 12,760 24,400 1 Estimated for the calendar year Ultimate AWTF generated Hauled Waste Evaluation Hauled waste is a potential source of revenue from tipping fees, as well as a source of solids that can be converted to biogas in the digesters. To efficiently receive and handle high strength hauled waste, a receiving station and equalization tank is recommended. The hauled waste receiving station would be installed on the first level of the proposed WAS thickening building. The receiving station would provide screens, and the ability to remove grit and floating solids prior to entering the equalization tank, which will be sized for a volume of 100,000 gallons. There will be pumps in order to transfer the hauled waste from a truck to the screening and grit removal system. The hauled waste would then be combined, using hose pumps, with the thickened WAS and thickened primary sludge in a blending tank, of volume equivalent to one day s volume of hauled waste or approximately 75,000 gallons, prior to digestion. There will be a set of pumps to transfer the blended sludge to the digesters. In addition to the infrastructure needed, accepting hauled waste will require operational and maintenance support. Accepting hauled waste also introduces risks to the digestion process, and identifying, negotiating, and receiving high quality hauled waste will also add complexity to the overall AWTF operation. At the same time, the opportunity to provide a positive net economic impact to the AWTF as well as providing environmental and public relations benefits makes receiving hauled waste an attractive alternative. A cost analysis was conducted on three alternatives to assist in the recommendation to receive hauled waste. The three alternatives that were considered are: Base Case Hauled Waste received at about 50-60% of the total feed to operate at design capacity 30% Hauled Waste Hauled Waste quantity is limited to 30% of the total feed to the digesters No Hauled Waste Only AWTF biosolids are digested. The results of the simple rate of return and payback period for the alternatives is included in Table ES-2. Executive Summary ES-3 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

10 Table ES-2. Hauled Waste Alternatives Cost Analysis Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Alternative Incremental Capital Annual Benefit 1 Simple Rate of Return Payback Period Hauled Waste Base Case 30% Hauled Waste No Hauled Waste $15,470,000 $892, % 17 $5,910,100 $529, % 11 $0 $272,454 N/A N/A 1. Annual Benefit = First Year Revenue from Electric generated + Offset of purchase of Nat Gas for heating + tipping revenue - HW disposal costs - Maintenance Costs (2% of Incremental Capital) The alternative limiting hauled waste to 30% of the digester feed was found to have a shorter payback period compared to the base case. This alternative merits further consideration since it offers the potential for the plant to incrementally increase the volume of hauled waste received while the plant monitors and evaluates the stability of the digestion process. The benefits derived from co-digesting hauled waste will be affected by many factors that will vary over time. The tipping fee, price for electricity sold to the utility, availability and characteristics of hauled waste are each significant contributors to the benefit received. A sensitivity analysis of the effect some of the variables will have on the project financial returns is presented in Section 7.4. Summary of Improvements A schematic of the recommended improvements program is shown as Figure ES-1. Waste Activated Sludge Gravity Belt Thickeners Gas Storage Sphere Biogas Pretreatment Combined Heat and Power Waste Flare Diluent Water Blending Tank Polymer Hauled Waste Primary Sludge Unloading With Rock Trap Gravity Thickeners Screen Equalization Tank Acid Phase Digester Primary Anaerobic Digesters Secondary Anaerobic Digesters Belt Filter Presses FUTURE Higher Cake Solids Dewatering Process followed by Heat Drying Biosolids Storage Land Application Figure ES-1. Schematic of Recommended Biosolids Improvements A summary of the recommended biosolids facilities is shown in Table ES-3. Executive Summary ES-4 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

11 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table ES-3. Recommended Biosolids Facilities Gravity Thickeners, Existing Hauled Waste Receiving Station, New WAS Thickening, New Primary Digesters, Refurbish and Upgrade Two Phase Digestion, New Refurbish Secondary Digesters Upgrade One (1) Secondary Digester Sludge Dewatering, Upgrade Two (2) Existing Diameter 80 ft, each New Building with WAS Thickening New Receiving Station 600 gpm Unloading Rate Screening, Grit, and Grease Removal 75,000 gal Holding Tank Hauled Waste Transfer Pumps 3 New 2 m Gravity Belt Thickeners 600 gpm Hydraulic Loading Rate Each 2 In Operation 16.5 hrs/day at Design Capacity New Building with Hauled Waste 100,000 gallon Blending Tank Sludge Transfer Pumps Mechanical Mixing Provisions for Direct Steam Heating Replace Pumps and Piping One (1) 300,000 gallon Acid Phase Digester 1.5 Days SRT Replace Roof on Both Digesters Refurbish Concrete and Brick Replace Piping Upgrade One Existing Digester to Function as a Primary Digester with Mechanical Mixer, and Recirculation with Temperature Control. Install Mechanical Mixer on One Existing Digester Two (2) New Centrifuges Boiler Building, Upgrade Cogeneration Building, Upgrade Gas Collection, Storage and Pretreatment, Refurbish and Upgrade Sludge Storage Sheds, Expand One (1) New Steam Boiler, 6,000,000 BTU/hr in Existing Building Two (2) New 500kW Biogas Reciprocating Engine Drive Generator Units, with Provisions for a Third Unit Combined Heat Recovery Replace Two (2) Low Pressure Compressors Replace Hydrogen Sulfide Removal Unit Replace Particulate and Condensate Removal Unit Existing Storage Tank Two (2) Existing One (1) New 15,000 cu ft Capacity Sludge Storage Shed Executive Summary ES-5 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

12 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water A rough order of magnitude (ROM) project cost estimate for each improvement is summarized in Table ES-4. The point estimates are based on the available information gathered in 2017, and are in 2017 dollars. The ENR Construction Cost Index on August 2017 was Recognizing the scope of each improvement is conceptual in nature, a low estimate and high estimate are also presented, the Low Estimate including a negative 20% contingency, and the High Estimate including a 50% contingency. Table ES-4. Project Cost Estimates Included Projects Low Estimate -20% Contingency High Estimate +50% Contingency Point Estimate 0% Contingency Primary Digester Improvements CHP Evaluation & Enginator Rehabilitation Hauled Waste and Gas & Power Generation Market Evaluation Secondary Digester Rehabilitation $9,500,000 $13,400,000 $11,100,000 (1) $600,000 $1,125,000 $750,000 $160,000 $300,000 $200,000 $2,900,000 $5,400,000 $3,600,000 Gravity Thickeners $1,500,000 $2,800,000 $1,900,000 CHP and Gas System Upgrades WAS Thickening and Hauled Waste Secondary Digester Rehabilitation $10,700,000 $20,100,000 $13,400,000 $7,800,000 $14,600,000 $9,700,000 $2,900,000 $5,400,000 $3,600,000 Gravity Thickeners $1,500,000 $2,800,000 $1,900,000 CHP and Gas System Upgrades WAS Thickening and Hauled Waste Secondary Digester Retrofit to Primary Digester & Acid Phase Digestion $10,700,000 $20,100,000 $13,400,000 $7,800,000 $14,600,000 $9,700,000 $7,650,000 $14,340,000 $9,560,000 Dewatering $6,100,000 $11,500,000 $7,600, Primary Digester Improvement Point, Low, and High Estimates based on July % Basis of Design Estimate. Executive Summary ES-6 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

13 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water A phased implementation plan, presented in Figure ES-2, was developed following the preparation of the biosolids facilities improvement projects and in consultation with CRW. The phased approach is intended to address immediate priorities while balancing recommended future improvements with CRW s other system-wide infrastructure needs. The immediate priority for the AWTF Biosolids Facilities is the rehabilitation of the primary anaerobic digesters and related equipment, such that the plant can fully utilize existing equipment and maintain a stable and reliable digestion process. The Primary Digester Improvements, identified as Phase 1, will provide greater reliability for digestion with improvements in mixing, recirculation and heating, and will be starting construction in Phase 2 will include the refurbishment of the enginators to provide more reliable service in the short term and will also include an investigation of alternative biogas utilization options. Phase 3 will include an expanded market analysis of hauled waste generators, and will develop recommendations for a fee structure for the implementation of a hauled waste program. Phase 4 addresses the reliability of the gravity thickeners and the secondary digesters with a planned refurbishment of each facility. Phases 5 and 6 include major infrastructure improvements to biosolids handling and resource (energy) recovery systems, and allow for an expanded hauled waste receiving program at the AWTF. It is anticipated that the Phase 5 and 6 projects will be further refined through evaluations performed in Phases 2 and 3. Figure ES-2. Biosolids Facilities Improvement Phasing Plan Executive Summary ES-7 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

14 1 Background 1.1 Introduction The solids handling facilities at the AWTF were originally constructed in 1959 and included primary digesters, vacuum filtration dewatering and incineration. The original digesters were converted to secondary digesters in the 1970s when new primary digesters and support facilities were installed. At the same time, gravity thickeners, gas storage, and a digested sludge pumping station were added. Following the 1970s upgrade, digested sludge was pumped off site to an incinerator facility which included vacuum filtration for dewatering, sludge drying, and incineration. A cogeneration facility was added in 1984 to generate electricity from digester gas. The original vacuum filtration dewatering facilities were replaced in 1988 with belt filter presses and dewatered solids were hauled to a landfill. The belt filter presses were replaced in Currently, dewatered solids are land applied on local farms and occasionally sent to landfill. In general, the findings from the Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Existing Conditions Report (February 2017) indicated that the biosolids related tanks and buildings are in fair to good physical condition. The mechanical, electrical, HVAC and Instrumentation and Controls systems on the other hand are in poor condition and are operating well beyond their expected life. One exception was the dewatering belt filter presses, which were installed in 2011, and are fully operational. 1.2 Objectives for Biosolids Management CRW is progressive with their goals and objectives for the biosolids facilities. They have long recognized there is real value in the biosolids which are generated by the AWTF, both through beneficial reuse of the biosolids, and also through utilization of the biogas that is generated during anaerobic digestion. Due to improvements in technology and advancements in operational philosophies, e.g. focus on energy efficiency and resource recovery since the AWTF biosolids facilities were installed, there are opportunities to expand on the resources recovered from the biosolids. CRW s goals for biosolids management include: Increase the energy recovery from biosolids, Develop facilities that provide operational and energy efficiency, Improve long term sustainability, Increase CRW revenue. 1.3 Purpose of Plan The purpose of the Biosolids Facilities Improvement Plan is to: Review the existing biosolids infrastructure at the AWTF, Determine existing and planning level solids handling capacities and opportunities for supplementing facilities for accepting and processing hauled waste, Identity alternatives for biosolids handling, hauled waste handling, digestion, and biogas utilization, Determine the biosolids facility needs and develop a plan for future improvements to address the need Background 1 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

15 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 2 Existing Conditions 2.1 Overall Process Description The AWTF existing solids handling processes consist of gravity thickening of combined primary sludge and WAS, anaerobic sludge digestion, belt filter press dewatering, and sludge storage. Gas generated from the anaerobic digesters is stored on site and utilized for boilers to provide heat to the anaerobic digestion process, building heat and fuel for a supplemental electrical cogeneration system. Figure 2-1 shows the process flow diagram for the existing solids handling facilities. Gas Storage Sphere Enginators Boilers Waste Flare Diluent Water Polymer Primary Sludge WAS Gravity Thickeners Primary Anaerobic Digesters Secondary Anaerobic Digesters Belt Filter Presses Biosolids Storage Land Application Figure 2-1. Existing Solids Process Flow Diagram 2.2 Current Solids Loadings Operating records for the time period from August 2013 to June 2017 were evaluated. The assessment of the liquid treatment data was limited to aspects that affect sludge production. Influent Flow The AWTF influent flow was reviewed to determine long term trends and evaluate peaking factors. Figure 2-2 shows the daily influent flow to the AWTF, and Figure 2-3 shows the monthly average influent flow. It should be noted that the influent flow stream does not include recycle streams from the sludge thickening, nor the sludge dewatering process. Existing Conditions 2 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

16 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 2-2. Daily Influent Flow Figure 2-3 Average Monthly Influent Flow The average daily flow for the period reviewed was 21.5 MGD, the maximum month was 37.5 MGD, and the maximum day flow was 74.4 MGD. The maximum month peaking factor is 1.7, and the maximum day peaking factor is 3.5. Existing Conditions 3 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

17 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The influent flow to the AWTF demonstrates fluctuations typical of a system with a combined storm and sanitary collection system, which exhibits much higher peaking factors than a separate sewer collection system. CRW is developing a long-term control plan for controlling combined sewer overflows, which may result in more flow conveyed to the AWTF. These system improvements would be expected to increase the amount of solids that are processed at the AWTF by a nominal amount. The storm water itself contributes minimal quantity of solids from normal runoff activity, but the storm water inlets do collect some solids which are eventually flushed to the AWTF. Influent Total Suspended Solids and Biochemical Oxygen Demand Figure 2-4 presents the average monthly influent concentrations of total suspended solids (TSS) and biochemical oxygen demand (BOD5) in milligrams per liter Figure 2-4. Average Monthly Influent BOD5 and TSS Concentration. The influent BOD5 and TSS loads, in pounds per day, directly influence the amount of sludge that the plant produces, and are presented in Figure 2-5. Existing Conditions 4 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

18 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 2-5. Average Monthly Influent BOD5 and TSS Loads Although there are significant fluctuations in the BOD5 and TSS loads, they have varied within the same range for the three year period reviewed, indicating they would expect to continue within the same range for some time into the future. The Long-Term Control Plan (LTCP) could result in more flow conveyed to the AWTF, and therefore result in a nominally higher influent solids (TSS) loading. The average BOD5 load for the time period was 24,600 lb/day, while the average TSS load was 27,700 lb/day, resulting in an average BOD5/TSS ratio of 0.89 lb/lb, which is typical of medium strength raw municipal wastewater. Primary Sludge Primary sludge is drawn off of the four primary clarifiers and pumped to the gravity thickeners. The daily primary sludge flow rate and the primary sludge solids loadings are shown in Figure 2-6 and Figure 2-7, respectively. Existing Conditions 5 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

19 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 2-6. Daily Primary Sludge Flow Figure 2-7. Daily Primary Sludge Total Solids Load Existing Conditions 6 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

20 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The daily primary sludge flow has been generally consistent during the time period studied. The daily load appears to be quite variable, but is indicative of variable results of periodic grab sampling concentrations multiplied by more consistent flow rates. The average primary sludge load was 22,500 lb/day. Waste Activated Sludge WAS is pumped from the mixed liquor channel following the aerobic / post anoxic reactors and prior to the polymer mix tank and discharged to the gravity thickeners. The daily WAS flow rate and WAS solids loadings are shown in Figure 2-8 and Figure 2-9, respectively. Figure 2-8. Daily Waste Activated Sludge Flow BNR Construction BNR Online The period for which the WAS data were reviewed captures process changes resulting from the 2013 AWTF Improvements Project which included liquid process upgrades to provide for Biological Nutrient Removal (BNR), which were substantially complete at the end of April During the construction period, from March 2014 through April 2016, aeration basins and secondary clarifiers were sequentially taken offline. The data from this period are not relevant to the biosolids planning. The May and June 2017 WAS data were higher than the other months due to a draw down in mixed liquor suspended solids (MLSS) concentration to meet the warm weather MLSS target, which is less than the cold weather target concentration. Although this transition will occur each year, the transition will be carried out over a longer period to keep the WAS flow rates within a more narrow range than that in WAS pumping operation was modified through the upgrades, changing from wasting settled solids from the final clarifiers to wasting mixed liquor solids. Flow rate increased to compensate for the lower concentration. The WAS load prior to October 2015 averaged 6,100 lb/day, while the WAS load since May 2016 has averaged 16,600 lb/day. During the period October 2015 through May 2016, due to startup of nutrient removal upgrades, highly variable wasting of activated sludge occurred. The increased WAS rates since May 2016 correspond to the change of operation as a result of the BNR upgrade and therefore this increase in WAS solids production is expected to continue. Thus, the recent upgrades have increased the WAS component of the solids load from 22% to 39% of the total load. Existing Conditions 7 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

21 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 2-9. Daily Waste Activated Sludge Total Solids Load BNR Construction BNR Online Sludge Thickening The combined average total primary and WAS solids sent to the gravity thickeners from May 2016 to June 2017 was 40,500 lb/day with a 61 to 39 percent split of primary sludge to WAS. As the sludge settles, the thickened sludge is drawn off from the bottom, or underflow, of the thickeners, and is pumped to the primary digesters. The daily flow rate and monthly average solids load of gravity thickener underflow are shown in Figure 2-10 and Figure 2-11, respectively. Existing Conditions 8 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

22 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure Daily Thickener Underflow Figure Average Monthly Thickener Underflow Total Solids Load The thickener underflow (i.e. feed to the primary digesters) has averaged 3% solids concentration for the period reviewed. The thickener underflow daily solids load has increased since May 2016 as a result of the BNR upgrade. The BNR upgrade included the addition of a supplemental carbon (methanol) to promote the denitrification reaction. The denitrification bacteria will utilize the supplemental carbon, and therefore yield more waste solids. Existing Conditions 9 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

23 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The average thickened solids load increased from approximately 25,100 lb/day before October 2015 to approximately 30,400 lb/day since May A solids balance between the overall average thickener influent and underflow since May 2016 shows a difference of 9,500 lb/day. Some loss would be expected to represent the solids being lost over the perimeter weir, or thickener supernatant. The data, however, show an average thickener supernatant load of 2,300 lb/day, about a quarter of what is expected based on the solids balance calculations derived from the measured loads in and out of the gravity thickeners. This imbalance is likely a symptom of irregular grab sampling of the supernatant. The supernatant is returned to the head of the activated sludge process. Sludge Digestion The thickener underflow load is a measure of the feed solids to the primary digesters, see Figure Total suspended solids digester loading prior to October 2015 was 25,000 lbs/day, and 30,400 lbs/day since May Figure Average Monthly Primary Digester Solids Load The volatile suspended solids (VS) component of the primary digester feed averaged 19,800 lbs/day prior to October 2015, and 23,700 lb/day since May 2016, see Figure Existing Conditions 10 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

24 Figure Average Monthly Primary Digester Volatile Solids Load Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Sludge Dewatering Figure 2-14 shows the monthly average dry cake solids discharged from the belt filter presses. The belt filter presses are generally operated 24 hours a day, 7 days per week. Figure Average Monthly Belt Folter Press Dry Cake Load Existing Conditions 11 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

25 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Since May 2016, the average daily primary digested solids feed to the belt filter presses was 20,600 lb/day, while the dewatered cake solids averaged 16,300 lb/day (and 20% solids) suggesting a belt filter press solids capture efficiency of 79%. Although this is less than the typical 90-95% efficiency, other factors should be considered such as the variabilities in the grab sampling, especially when considering the secondary digesters are not mixed. Also, the belt filter press operations are variable from month to month depending on several factors including biosolids disposal limitations and available storage capacity within the secondary digesters. As shown in Figure 2-14, the volume of cake solids processed varies significantly from month to month Biogas Production Anaerobic digestion of sludge results in methane gas production. Figure 2-15 illustrates the average monthly gas production during the review period. Although the data are somewhat limited, and influenced by variable operating conditions and digestion process equipment issues, the data suggest that the digestion process is performing either below or at the low end of typical ranges for gas production parameters. Based on the available plant data, digester performance including volatile solids loading and destruction, and associated gas production, were not satisfactory when the process should have been more stable, before and after BNR upgrade startup. Data shown in Figure 2-15 is for the period August 2013 June Figure Average Monthly Primary Digester Gas Production Data prior to BNR Upgrade startup are for the period August 2013 October The daily average methane gas production was approximately 150,000 cubic feet per day (cfd). The maximum month was about 184,000 cfd and maximum daily gas production was 291,500 cfd. Primary digester gas flows have been fairly consistent, with several significant drops that took several months from which to recover. It is unknown what caused these drops, but the BNR Upgrade construction, and fouling of heat exchangers are possible contributing factors. CRW has also reported issues with the gas flow metering. The BNR Upgrade startup period extended from October 2015 to May 2016, and post startup from May Digester performance data for the entire period of data, and before and after the startup period, is summarized in Table 2-1. Existing Conditions 12 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

26 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 2-1. Digester Performance Summary Period Description of Time Period Feed VSS (lb/day) Digested Sludge VSS (lb/day) Destroyed VSS (lb/day) Destroyed VSS (%) Digester Gas (cfd) Gas Produced (cf/vss fed) Gas Produced (cf/vss destroyed) Aug 13 Oct 15 May 16 June 17 Aug 13 June 17 Prior to BNR Upgrade Construction After BNR Upgrade Overall Period Reviewed 19,850 8,900 10, , ,700 12,370 11, , ,300 10,000 11, , Gas production should fall within the following ranges: 8-12 cf gas / lb VSS fed (Averages for the 3 periods range from ) cf gas / lb VSS destroyed (Averages for the 3 periods range from ) Although cf gas / lb VSS destroyed is within the typical range, the fact that the cf gas / lb VSS fed is low indicates that the destruction should be better. Several factors, with combined effects contribute to the poor performance: 1. Low feed solids concentration, causing a low solids retention time. 2. Insufficient digester temperature. (Optimum 98 deg F, minimum 95 deg F.) 3. Variations in digester temperature. 4. Inadequate mixing. 5. Batch feeding of hauled waste to digester (2017) Collectively, these factors will be addressed later in this report, especially related to sludge thickening and digester heating and mixing. These improvements will allow for increased VSS destruction and associated gas production, in particular with respect to the increase in WAS since the BNR upgrade. Biogas Utilization The methane gas is compressed and stored in a spheroidal storage tank, and it is also used within the facility as fuel for boilers that provide heating of buildings and digester sludge and as fuel for two (2) cogeneration units, referred to as enginators. Excess gas that cannot be used is sent to be flared at a waste gas burner. Figure 2-16 illustrates the monthly total usage for the period evaluated, divided into usage for each gas consumer. CRW provided air flow data for total gas production, boiler usage, and the waste flare. Enginator gas use was calculated using these values. Existing Conditions 13 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

27 Figure Monthly Gas Usage: January 2014 July 2017 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The majority of gas produced by the digesters is utilized by CRW either as building heat or generated electricity. 2.3 Existing Solids Handling Facilities Introduction The existing solids handling facilities are briefly reviewed in this section. Included in the discussion are key design and operating information. More detailed process and specific equipment information is included in the Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Existing Conditions Report (February 2017) Gravity Thickeners Primary sludge is pumped from the primary clarifiers by pumps in the Control Building basement through pipe tunnels 1 and 2 to the gravity thickeners. Scum is collected from the surface of the primary clarifiers and is sent to two holding pits. Supernatant from these pits is pumped to the gravity thickeners, while scum is pumped out and removed offsite by a contracted hauler. Scum from the secondary clarifiers is pumped with scum pumps to combine with WAS Pump Station force main. The primary sludge and WAS force mains combine with diluent water (plant effluent from the chlorine contact tanks and pumped from the Settled Sewage Pump Station) prior to a thickener distribution box, which distributes flow to both gravity thickener tanks. The thickened sludge is drawn off the cone bottom of the thickeners by three (3) recessed-impeller, non-clog sewage pumps, which send thickened sludge to the primary digesters. Overflow from the gravity thickeners is returned to a manhole (MH-7) and is returned to the head of activated sludge process. Existing Conditions 14 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

28 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water At the current conditions, the average combined sludge sent to the gravity thickeners is approximately 39,900 lb/day (18,100 kg/day). With a total surface area of approximately 10,000 ft 2 (934 m 2 ), the average mass loading rate to the gravity thickeners is 0.17 lb/ft 2 hr (0.81 kg/m 2 hr) Primary Digesters Currently, the combined thickened sludge is transferred to two primary digesters for anaerobic digestion. The primary digesters are circular reinforced concrete tanks with sloped bottoms and covered by fixed roofs. Within the tanks, anaerobic bacteria convert the volatile solids in the sludge to volatile acids, and then to carbon dioxide and methane. The facility has only been operating one digester. The contents of each digester are mixed by drawing off digester gas from the top of the digester roof, compressing the gas with a rotary lobe compressor, and then discharging it through eight nozzles located approximately 1/3 below the liquid level in each of three 5-foot diameter eductor tubes. The rising gas bubbles pull sludge up with them through each eductor tube and mix the tank contents. To keep the digestion process at an optimal level, the temperature in the digester should be maintained at approximately 98 F. To accomplish this, sludge is recirculated through heat exchangers, which are provided with hot water from the boiler house. Three recessed impeller pumps pull sludge from the bottom of the digesters, circulate it through three concentric tube heat exchangers and back into the top of the digesters. The two digesters, their associated piping, and equipment have experienced vivianite precipitation and buildup. Vivianite is a hydrated iron phosphate mineral and has accumulated to such an extent that Digesters No. 2 s valves are no longer operational. The refurbishment of the primary digesters is currently being designed. Improvements will include: Replacement of gas mixing system with a mechanical mixing system, Replacement of the primary digester fixed covers, Replacement of the gas and sludge piping internal to the digesters and piping and valves within the Primary Digester Control House, Replacement of the waste gas flare, Replacement of the primary sludge recirculation pumps, Replacement of the primary sludge transfer pumps, Addition of a new Electrical Building to house motor control centers and control panels for the Biosolids Facilities. The primary digester concentric tube heat exchangers are not being modified with the current project. The heat exchangers are sufficiently sized for the digester operation when not fouled with mineral buildup (vivianite). Currently, the heat exchangers become fouled and cannot maintain digester temperature within months of operation. When fouled, the affected piping and heat exchanger tubes are replaced at a cost of approximately $50,000. However, accommodations for steam lances are being implemented into the primary digester improvements. These along with direct steam injection in the feed stream and recirculation lines will provide a future means of eliminating vivianite buildup and for maintaining optimal digester temperatures Secondary Digesters Sludge from the primary digesters can be transferred by gravity to the secondary digesters. The secondary digesters are primarily serving as digested sludge storage from where excess liquid can be decanted. The settled solids are drawn off from multiple draw off points and pumped to dewatering. Supernatant from the secondary digesters flows by gravity to the inlet channel of the primary clarifiers. There is also a pipeline which allows for truck loading of liquid digested sludge into tanker trucks. Truck loading has not been utilized for many years. There are also two progressing cavity pumps that can be used when necessary to overcome the head in the secondary digester, e.g. when lowering the level in the primary digester for maintenance or inspection. Each Existing Conditions 15 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

29 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water digester includes piping, accumulator and compressor to withdraw digester gas from the roofs of the digesters and send it into the digester gas system Dewatering Facilities Digested sludge flows by gravity through two separate pipelines with in-line sludge grinders, and then is pumped to the belt filter presses with hose pumps. Polymer is added through a ring injector, which is upstream of a mixing valve. The sludge is then fed to the gravity section of the belt filter presses. The AWTF currently operates two (2) belt filter presses (BFP) to dewater digested sludge. The two (2) in-line sludge grinders break down larger solids, and replace the function of the in-line grinder pumps in the digested sludge pumping station. Discharges from the three (3) belt filter press hose pumps can be directed to either of the 2.5 meter wide belt filter presses. Prior to being deposited on the belt filter press, the sludge is conditioned with polymer to promote the coagulation of solids. The polymers are first received as a powdered solid, delivered in supersaks. The polymer supersak is then placed on a skid, from which polymer is metered by a screw conveyor into a pneumatic line that pushes it into a 3,300 gallon fiberglass polymer mix tank. Water is added to the polymer and the contents are mixed. Once the polymer is conditioned, it is pumped by two progressing cavity pumps to a storage/feed tank, also a 3,300 gallon fiberglass tank. The polymer solution is then pumped into an injection ring located on each belt filter press feed pipeline. During the dewatering operation, as the dewatered cake is discharged, the press belts are continuously washed with spray water. A wash water skid equipped with three booster pumps provides the pressure to adequately wash the belts. The cake is discharged from the belt filter press onto a ribbed belt conveyor which conveys the cake into a dump truck that transports it to the covered storage area. The AWTF currently uses belt filter presses for dewatering. Belt filter presses have many advantages including: Low capital cost Low energy consumption Simple operation and maintenance Ability to handle stringy solids (i.e. rags) and plastics Historically the belt filter presses are fed at an average flow rate of 60 gpm, and the two units operate an average of hours total a day. This corresponds to a solids feed rate of approximately 700 lbs/hour. After the implementation of separate WAS thickening (discussed later in this report), which would increase the digested sludge feed concentration, the solids loading rate to the BFPs could be increased while producing dry cake solids of 20%. Although the current dewatering operations are having difficulty meeting the 20% dry cake solids, a study is being pursued to investigate potential improvements to the dewatering operations. A conservative design solids feed rate at the higher digested sludge solids content would be 1,000 lbs/hour. At this increased solids loading rate, two BFPs each operating an average of 16 hours a day, the AWTF could process 32,000 lbs dry solids/day Boiler Building Digester gas is burned in two boilers to provide hot water for heating the primary digesters, and space heating for buildings. The boilers can also be fired with fuel oil, but there has been sufficient digester gas available for many years. The amount of biogas received by both boilers and the heat produced from both is summarized in Table 2-2. Existing Conditions 16 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

30 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 2-2. Existing Total Boiler Data Winter 1 Summer 2 Biogas Usage (cf/day) 34,400 13,200 Heat Production (BTU/day) 20,600,000 8,000, October to March averaged from April to September averaged from 2014-June Cogeneration Facility Digester gas is also used to power two internal combustion engine driven electric power generators. The power generated is exported onto the utility grid. The amount of biogas received by both enginators and the electricity in kw produced by both enginators in total on a daily basis can be seen in Table 2-3. Prior to combustion, the digester gas is filtered by a condensing filter to remove condensable water vapor from the gas. The engine cooling is performed with roof mounted radiators, with closed loop circulation back to the engine blocks. Table 2-3. Existing Total Enginator Data Winter 1 Summer 2 Biogas Usage (cf/day) 142, ,000 Electricity (kw) 2,200 2, October to March averaged from April to September averaged from 2014-June Gas Collection and Storage The digester gas is routed through the pipe tunnels, through the Digested Sludge Pump Station, then compressed in the Gas Compressor Building and stored in a spherical tank. The tank has a pressure relief valve to avoid damage to the tank. Excess gas is burned off at an adjacent ground level waste gas flare Sludge Storage Facilities Dewatered sludge is stored in two sludge storage sheds located at the north end of the plant site. Each sludge storage shed has a concrete floor and partial walls, and is covered with a metal roof supported by steel beams. Dewatered sludge is stored while awaiting transportation to the land application site. Dewatered sludge that is less than 20% cake solids cannot be stored at the land application site, nor can it be applied to frozen ground. Therefore, anytime cake solids are less than 20% the dewatered sludge is stored at the AWTF until it can be land applied. A separate study is being undertaken to improve existing dewatering operations. Existing Conditions 17 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

31 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 3 Biosolids Projections 3.1 Design/Future Biosolids Projections A review of 3 years of influent flows, BOD5, and TSS as summarized in the Biosolids Facilities Improvement Existing Conditions Report, February 2017, concluded the loadings to the plant vary within a consistent range. At the same time, CRW anticipates only a modest number of new connections to the collection system, indicating that the future primary sludge and WAS generated at the AWTF can be expected to remain within the same ranges. For the period since the BNR upgrade was completed (April 2016), the WAS volumes have increased substantially, coinciding with the modification to wasting mixed liquor rather than settled sludge from the final settling tanks. Taking this into consideration, Table 3-1 includes the current average and projected AWTF sludge design criteria. Table 3-1. Sludge Design Criteria (AWTF) Average, Current 1 Projected Design Values Influent Wastewater Flow 19.5 MGD 37.7 MGD 2 Primary Sludge WAS 25,600 5,800 mg/l 0.44 MGD 16,600 2,700 mg/l 27,750 lbs/day 5,800 mg/l 0.60 MGD 25,000 lbs/day 2,500 mg/l MGD 1.2 MGD 1. Data from May 2016 to June 2017 (after BNR upgrade online) 2. AWTF BNR Upgrade Design Maximum Month 3. Calculated using a peaking factor of 1.3 times the current annual average WAS mass rates 4. Based on continued wasting from mixed liquor channel, concentrations may range from 2,000 to 3,000 mg-tss/l Table 3-2 compares the AWTF generated solids to the digester capacity. The remaining digester capacity could be available for hauled waste, discussed further in Section 3.2. Biosolids Projections 18 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

32 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 3-2. Solids Digestion Capacity Condition Digester Capacity VS Loading (lbs / day) 61,000 Current Loading 23,700 Projected Loading from AWTF 36,560 Available Loading 24, Proposed Hauled Waste Projections Approximately 100 potential high strength waste (HSW) generators were contacted to determine whether their wastes could be valuable waste streams to be hauled waste for co-digestion at CRW s AWTF. Of the potential sources, five were identified as promising sources within the 50-mile survey radius. Table 3-3 identifies these potential sources along with projected waste characteristics. A more comprehensive market assessment is included in Appendix A as Technical Memorandum No. 5. Table 3-3. VSS Loadings from Selected HSW Generators HSW Source Daily Volume (MGD) % Solids TVS % VSS (lbs. day) Utz Quality Foods % 80% 7,126 Empire Poultry % 80% 6,672 Hershey Creamery % 98% 5,848 Grease Trap Waste % 80% 480 Warrell % 80% 110 Total volume per day (gallons) 36,530 Weighted average % solids 7.9% Volume lbs. of VSS per day 1. Daily volume provided by generator; % solids and TVS% estimated 2. Calculated based on population served and typical per capita volumes generated 20,236 In addition to optimizing the type and composition of hauled waste the AWTF should receive, the quantity of hauled waste needs to be considered. The total digester capacity in terms of volatile solids is finite, thus the ratio of solids generated by the AWTF to the amount of hauled waste can be a useful indicator of digester capacity. Table 3-4 shows the ratios of HSW required to maximize the capacity of the digesters at different loadings. Biosolids Projections 19 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

33 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 3-4. Ratio of HSW to AWTF Solids at Selected Loadings Loading Rate AWTF Solids Loading (lbs. VSS/day) HSW Solids Loading (lbs. VSS/day) Total Solids Loading (lbs. VSS/day) % HSW to solids feed Current Average 21,300 20,240 41,540 49% Digester Capacity (37.7 MGD) 36,560 24,440 61,000 40% The five identified sources represent substantial volatile solids loadings, which represent 40% of the total VSS loading of the two anaerobic digesters at design flow. At the current loading, the five HSW sources nearly double the current VSS loading. Accepting only the Utz or Empire Poultry feedstock provides approximately 49% of the feed rate to the digesters at current VSS loadings, which could correspond to an increase of 50-80% in biogas volumes, based on the available data. 3.3 Biogas Utilization The addition of new CHP technology would increase the amount of heat and electricity outputted from the same amount of biogas. In addition, the amount of biogas generated will increase with increased volumes of hauled waste. However, the projected biogas increase will take many years to reach its design level, thus calculations were initially performed to determine the CHP outputs based on current biogas conditions, which assumes no additional biogas production from increased hauled waste. The results are shown in Table 3-5. Table 3-5. Current Biogas Generation with New CHP System Winter 1 Summer 2 Biogas Usage (cf/day) 142, ,000 Size (kw) Electric Efficiency (%) Heat Efficiency (%) Heat Production (Btu/day) 37,000,000 36,000,000 Electric Production (kw) 10,800 10, October to March averaged from 2013-June April to September averaged from 2014-June 2017 When compared to the existing heat and electricity production from the boilers and enginators (as summarized in Tables 2-2 and 2-3 respectively), the production from the CHP System is significantly more for the current biogas production rates. Further, once identified project upgrades have been constructed and on-line, and hauled waste contributions are at design capacity, biogas emissions will increase significantly. Table 3-6 shows the CHP outputs based on future conditions. Biosolids Projections 20 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

34 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 3-6. CHP: Future Conditions Winter Summer Biogas Usage (cf/day) 397, ,000 Size (kw) Electric Efficiency (%) Heat Efficiency (%) Heat Production (BTU/day) 98,600,000 98,600,000 Electric Production (kw/day) 28,900 28,900 Comparing Table 3-5 to Table 3-6, CHP will produce approximately three times the amount of heat and electricity at the future conditions as it will under current conditions. Biosolids Projections 21 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

35 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 4 Biosolids Technology Assessment 4.1 Sludge Thickening Gravity thickeners which only thicken primary sludge can be loaded at higher mass rates than those that thicken combined primary and waste activated sludge. In addition, with only primary sludge, the thickened primary sludge in the underflow is expected to settle to a higher concentration of solids. Therefore, separating the primary sludge and waste activated sludge would allow for a higher percent solids to be fed into the digesters. Table 4-1 summarizes typical design criteria for gravity thickeners. Table 4-1. Typical Design Criteria for Gravity Thickeners 1 Type of Solids Influent Solids Conc. % solids Expected Underflow Concentration % solids Mass Loading Rate lb/sq ft/hr (kg/m 2 /hr) Max. Overflow Rate gal/sq ft/d (m 3 /m 2 /d) Primary (4-6) ( ) Primary and WAS and Iron (1.5) N/A 1. WEF Manual of Practice No. 8 The thickener underflow is currently averaging 3% for the period reviewed. Increasing this to 5-6% solids would nearly double the solids retention time in the digesters. At an average mixed liquor suspended solids concentration of 2,700 mg/l, there is currently an average of 0.72 million gallons a day of WAS. WAS could be thickened separately from the primary sludge to a solids concentration of 5-6%. The overflow rate of the thickener was evaluated to determine if the rate when thickening only primary sludge is too low. The primary sludge flow rate has averaged 0.44 MGD over the period studied. Thickening this stream separately with a 4:1 dilution water to sludge ratio would result in an overflow rate of 220 gal/sq ft/d (9.0 m 3 /m 2 /d), which is low and subject to floating sludge, odors and septicity. Operating one thickener would be recommended to keep the dilution water quantity reasonable, and result in an overflow rate of 440 gal/sq ft/d (18.0 m 3 /m 2 /d). Gravity thickening is not well suited to thickening WAS due to the limited settleability equating to much larger thickeners needed than for combined sludge. In addition, the volume of WAS is relatively high due to mixed liquor being wasted rather than clarifier underflow, resulting in an average total suspended solids of the WAS of approximately 2,700 mg/l. A more conservative value of 2,000 mg-tss/l is utilized in the thickening equipment sizing. In addition to gravity thickening, there are several proven technologies in widespread use for thickening waste activated sludge including: Gravity Belt Thickeners Dissolved Air Flotation Thickeners Centrifuges Rotary Drum Thickeners Biosolids Technology Assessment 22 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

36 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Volute Thickeners The potential also exists for sludge in the future to be wasted from the return activated sludge (RAS) stream, which would have higher solids content. This would require piping and pumping changes. Under this scenario, solids content of the WAS would be 4,000 to 5,000 mg-tss/l, greatly reducing the volume of sludge to be pumped and thickened. The thickening equipment will need to take this into consideration, and will also be a positive benefit in all regards. Seasonal changes in activated sludge mixed liquor suspended solids (MLSS) targets can result in WAS volumes much higher than average, depending on the length of time the reduction in solids is desired. The WAS thickening equipment will be sized to operate with one unit out of operation for no more than 18 hours a day, 7 days a week at the design WAS volumes of 1.2 MGD. Gravity Belt Thickener (GBT) The GBT is well suited to thickening the low solids content (0.2 % solids) of the AWTF WAS to reliably above 5% solids. GBTs are similar in operation and construction to the belt filter presses that the AWTF currently uses to dewater stabilized sludge. GBTs offer the following advantages: Relatively low capital cost Relatively low power consumption High thickened solids concentrations (>6%) are possible GBTs have the same disadvantages as belt filter presses, so the AWTF operations are already familiar with them. Disadvantages include: Reliance on the use of polymer Required ongoing housekeeping efforts Building corrosion due to high humidity GBTs are hydraulically limited, rather than solids loading limited. A typical gravity belt thickener can thicken 300 gpm per meter of effective belt width, of WAS at 2,000 mg/l, and produce 5-6% solids thickened WAS (or TWAS). Alternatively, if waste sludge were taken from the RAS stream, the volume of WAS would be significantly less. The GBTs would therefore operate fewer hours, and there would be the potential for less polymer to be required to consistently attain 5-6% solids. Dissolved Air Flotation (DAF) Thickener Dissolved air flotation (DAF) has been successfully applied to thickening WAS for many decades. In the DAF thickening system, solids and liquids are separated by introducing fine air bubbles into the liquid phase, the bubbles tend to attach to the solids and lift the solids to the surface where they are collected by a skimmer system. The main components of the DAF thickener are a tank and an air introduction system. The air introduction system would include recycle pumps to return a portion of the subnatant liquid into an air saturation tank where pressurized air is introduced, typically up to 75 psi. The saturated recycle stream is then introduced into the WAS stream at the influent into the DAF tank. The reduction in pressure from the air saturation tank to the DAF tank causes the creation of small air bubbles distributed throughout the influent stream. The floating solids are then collected by a skimmer mechanism, and the subnatant is returned to the head of the plant. DAF tanks are also outfitted with bottom solids removal as well, for heavier solids that sink to the tank floor. In a rectangular tank configuration, this can be a screw conveyor. In a circular tank configuration, scraper blades mounted on a rotating truss, similar to a settling clarifier, are utilized to collect the solids to a sump. Biosolids Technology Assessment 23 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

37 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The lower than typical TSS in the WAS (nominally 0.2 % TSS) will lower the expected thickened concentration possibly only to within the range of 3-4 %. Additionally, until pilot testing could be conducted, the design would be kept on the conservative side of the typical criteria, making the DAF tank approximately 1,300 sq ft. This could be configured as a rectangular steel tank (approximately 16 feet by 80 feet long), or more likely as a concrete circular tank (approximately 40 foot diameter) similar in configuration to a settling clarifier. Two DAF tanks would be required to provide redundancy. Centrifuge Use of a centrifuge would also be considered a common application for thickening WAS, and is applicable to low solids concentration WAS. The centrifuge utilizes an outer shell, referred to as the bowl, and an inner screw, referred to as the scroll. The bowl will rotate at speeds in excess of 1,500 rpm to produce centrifugal forces of hundreds of times the gravitational force. The scroll rotates slightly faster (or slower in some manufacturer s designs) than the bowl to create a differential speed. The WAS stream is introduced into the center of the centrifuge through a hollow scroll shaft. The solids are forced to the inside face of the bowl and the scroll will push them towards the discharge. The liquid portion flows on top of the solids and past the scroll and moves towards the opposite end where it overflows a weir and goes into the effluent piping. Polymers are generally used to improve the performance of the centrifuge. There are many factors that affect the centrifugal thickening process results including flow rate, bowl and scroll geometry, maximum operating speed, feed rate, and the solids characteristics. Therefore, there are no specific design criteria for centrifuges, but instead pilot testing would be recommended to determine the design criteria. Properly sized, the centrifuge can consistently produce thickened WAS in the 5-6% target range, with solids capture rates of at least 90%, even with the low WAS TSS concentrations. The centrifuge has some disadvantages that need to be considered, including significant relative power consumption, high noise levels, and specialized maintenance skills requirements. For CRW the advantages are a smaller footprint which may reduce the building size required, thereby providing a competitive capital cost comparison between the advantages and disadvantages. Rotary Drum Thickener Rotary drum thickeners have many successful installations in regards to thickening waste activated sludge. Rotary drum thickeners have low power demands, are simple to operate and maintain, and generally have low overall life cycle costs. The footprint of a rotary drum thickener is less than that required by a comparably sized gravity belt thickener. However, few installations are reported to be thickening WAS with TSS as low as 2,000 mg/l. The low TSS of the AWTF WAS, will likely require relatively high rates of polymer, and could result in poor solids capture. The use of a rotary drum thickener would not be recommended without first piloting to determine its cost effectiveness in this application. Volute Thickener The volute thickener has a center conveying screw pushing the solids that are larger than the openings in the dewatering drum towards the discharge end. The volute thickener utilizes the annular space between donut shaped plates to separate out the solids. The volute thickener has relatively low capital costs and low energy consumption. The volute thickener has relatively few installations in the United States, but has fewer moving parts than the belt filter press or centrifuge which could translate to lower maintenance costs. Biosolids Technology Assessment 24 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

38 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water WAS Thickening Recommendations The GBT has several advantages over the centrifuge and DAFs including: Low capital cost Low energy consumption Simple operation and maintenance Ability to handle stringy solids (i.e. rags) and plastics In addition, the AWTF operations staff is familiar with the operation of a GBT, as the equipment is very similar to a belt filter press. One of the disadvantages of the GBT is the physical size is larger than a similar capacity centrifuge. The use of a centrifuge will reduce the overall size of the thickening building, which would offset some of the higher capital costs of the centrifuge. A proposed thickening building would house the GBT facilities including the wash water booster pumps, the polymer handling system, and thickened WAS (TWAS) transfer pumps. The TWAS would be stored in a holding tank to allow consistent flow to the digesters when blended with the gravity thickened primary sludge. The existing gravity thickeners would continue to thicken primary sludge, but only one thickener would need to be online at a time. 4.2 Hauled Waste Handling WAS thickening will increase the solids concentration fed to the digesters, and the existing digesters will then have additional excess capacity, over what is needed to stabilize the AWTF generated solids. The excess capacity can be utilized to digest hauled waste. The hauled waste generators would be charged tipping fees. The hauled waste will also produce additional biogas that can be utilized to generate electricity. Hauled waste will be delivered on tanker trucks varying in size. Handling the waste will require unloading, pretreatment, flow equalization, and pumping to the digesters, including the following facilities. Truck unloading station with containment Automated billing ticket generation Rock trap Two (2) Screening washing units with bypass for grease Two (2) transfer pumps One (1) equalization tank totaling a working volume of one (1) times the daily expected volume Tank aeration/mixing system with odor control Two (2) Transfer pumps to the primary digesters The mechanical equipment for handling hauled waste could be housed in the same building as the proposed WAS thickening process equipment. Although one screening unit could be sized to handle all of the projected hauled wastes, two units are recommended for redundancy. 4.3 Anaerobic Digestion Over the years there have been many variations on anaerobic digestion of wastewater sludge, which include: Operation at mesophilic (95 99 º F) and thermophilic ( º F) temperatures Two stage (Primary and Secondary) mesophilic (Harrisburg AWTF) Two stage mesophilic and thermophilic operation Use of egg shaped digesters Operating two digesters in series with one at mesophilic and one at thermophilic temperatures (Temperature Phased Anaerobic Digestion or TPAD) Biosolids Technology Assessment 25 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

39 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Two phase (acid phase) digestion Given that the existing digesters at the AWTF are structurally sound, and there are plans to refurbish the mechanical systems, the use of egg shaped digesters is not considered. Thermophilic digestion is more difficult to control than mesophilic and requires more energy input to maintain the higher temperatures. Advantages of thermophilic digestion over mesophilic include the potential to produce more biogas, and better dewatering characteristics. Redesigning the digesters and heating system for thermophilic operation is not warranted based on the current plans for biosolids at the facility. Two phase digestion separates the two major types of reactions that take place during anaerobic digestion - acid formation and methane generation. Two phase digestion with an acid phase digester would take advantage of the AWTF existing infrastructure and would allow for more effective use of the anticipated biosolids and hauled waste. Figure 4-1 is a schematic of two phase digestion. Minimizing potential for foaming in the main digesters is another of the advantages of two phase digestion. The acid phase digester would be designed with a greater than 1:1 ratio of height to diameter to minimize the footprint, and reduce unmixed zones within the tank. See Section 6 for more information on the acid phase digester. The practicality of capturing the biogas from the secondary digesters was also considered. The primary digesters currently destroy an average of 54% of the feed volatile solids. Even by making the aggressive assumption that the secondary digesters could increase this by another 5 percentage points to 59% total volatile solids destruction, the biogas released in the secondary digesters would equate to 40,000 cubic feet of biogas per day at capacity (37.7 MGD). Considering that the value of electricity generated by this additional gas is approximately $50,000 per year, the simple payback on installing new covers and gas collection system, would be more than 50 years, and is therefore not justified. Figure 4-1. Schematic of Two Phase Anaerobic Digestion Biogas Feed Sludge Heat Exchanger Acid Phase Digester Methane Phase Digesters (Existing Primary Digesters) To Secondary Digesters (Holding Tanks) Biosolids Technology Assessment 26 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

40 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 4.4 Dewatering Given the restrictions on storing dewatered sludge with less than 20% solids offsite, the dewatering process design target will be a minimum of 20% solids. Additional acceptance of hauled waste will increase the digested sludge that will need to be dewatered. These two conditions are considered, along with the current and proposed dewatering requirements in evaluating alternative dewatering technologies. Several dewatering technologies claim consistent biosolids cake dewatered to above 20% solids, including: Centrifuge Screw Press Volute Dewatering Press Rotary Press Other than the centrifuge, pilot testing would be highly recommended to confirm actual average percent solids performance at the AWTF. Centrifuge The centrifuge is widely utilized in dewatering biosolids, with high cake solids and high throughput as major advantages over most other technologies. Figure 4-2 shows an illustration of a centrifuge. Figure 4-2. Cutaway View of Biosolids Dewatering Centrifuge Credit: Centrisys Compared to the other technologies below, the disadvantages of the centrifuge include: High energy consumption High capital and maintenance cost Specialized maintenance skills The centrifuge has several advantages compared to other technologies including: High volumetric and solids loading capacity compared to unit size High dewatered cake solids Fully enclosed operation Biosolids Technology Assessment 27 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

41 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Screw Press and Volute Dewatering Press The screw press and volute dewatering press are similar in overall configuration, with a center conveying screw pushing the solids that are larger than the openings in the dewatering drum towards the discharge end. See Figure 4-3 for a typical screw press, and Figure 4-4 for a volute dewatering press. The screw press uses a static perforated, or slotted drum which separates the solids. The volute press utilizes the annular space between donut shaped plates to separate out the solids. The screw and volute press both have low capital costs and low energy consumption. The volute dewatering press has relatively few installations in the United States, but has fewer moving parts than the belt filter press or screw press which should translate to lower maintenance costs. Figure 4-3. Screw Press Credit: Schwing Bioset, Inc. Biosolids Technology Assessment 28 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

42 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 4-4. Volute Dewatering Press Credit: Process Wastewater Technologies, LLC Rotary Press The rotary press utilizes two vertically oriented plates with slotted openings, see Figure 4-5 for a general arrangement of a six channel rotary press. Flocculated biosolids are pumped in between the plates which separates the solids from the filtrate. The slow rotation speed of the plates provides friction to restrict the solids movement and provides compression of the solids cake to control the cake solids. The rotary press has a lower throughput than the screw press or belt filter press and therefore requires more floor space. The room where the existing belt filter presses are located may not be large enough for the required rotary presses, so that aspect would require evaluation. Biosolids Technology Assessment 29 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

43 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 4-5. Six Channel Rotary Press Credit: Fournier Industries 4.5 Vivianite Control The AWTF encounters significant mineral deposit buildup in the anaerobic digester recirculation/heating piping and heat exchangers. Every months the buildup becomes significant enough to cause the degradation of heat exchanger, pump and valve performance. The AWTF currently replaces the piping and heat exchanger tubes each time the ability to maintain the digester temperature degrades. Considering the AWTF utilizes ferric chloride for phosphorus precipitation and removal, and that the worst buildup is in the heat exchangers and downstream, i.e. the hottest sludge temperatures in the system, the mineral is likely vivianite (iron phosphate). Vivianite can be identified by its characteristic blue-green color, is soluble in hydrochloric and nitric acids, and loses solubility when temperatures rise. There is currently no economical method from recovering the phosphorus from the iron phosphate. There are two primary methods to control vivianite deposits: reduce the temperature of the sludge coming out of the heat exchanger and/or reduce areas of high turbulence. Changing phosphorus precipitant chemical to an aluminum salt was also considered, but aluminum salts tend to have a higher cost, and struvite (solid magnesium ammonium phosphate) buildup is also a possibility. Given the congestion of piping within the primary digester pumping station there are few opportunities to address areas of high turbulence in the piping by removing bends and tees or introducing longer sweep elbows. Reducing the temperature rise of the sludge in the heat exchanger was investigated, but minimal improvement is expected. To mitigate vivianite buildup, it is recommended to heat the primary digesters with direct steam injection. In the primary digester improvements, provisions for steam lances, to be installed in the future, will be installed into the primary digesters. When the proposed CHP technology is installed, steam can then be produced from the heat output of the technology and conveyed to the steam lances to keep the digesters at a consistent, optimal temperature. Direct steam heating will help eliminate vivianite build up in the heating loop as well as eliminate the Biosolids Technology Assessment 30 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

44 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water need for the existing external heat exchangers. During the detailed design of the steam heating system, an external direct steam heat injection exchanger should be evaluated to supplement the steam lances. 4.6 Biogas Utilization Assessment There are several potential beneficial uses for biogas including the following: Combust the biogas and recover the heat and kinetic energy, e.g., combined or separate heat and power generation Use a fuel cell to generate electricity and heat Off-site use of the biogas, e.g., as natural gas substitute Use as fuel to heat the digesters Use as fuel for heat drying biosolids The AWTF is currently utilizing a hybrid heat and power generation, with partial recovery of heat from the engine driven generator, and the use of separate boilers for additional heat generation capacity. Integrating the heat and power generation into a combined heat and power system would improve the overall energy efficiency. In combined heat and power, all of the biogas is burned in the engine or turbine driven generator, and the heat for the digesters is supplied by the waste heat generated by the engine. A fuel cell can also be used in the generation of combined heat and power. See Figure 4-6 for a schematic of the proposed CHP system integrated in the AWTF biosolids process. Figure 4-6. Schematic of CHP Option for Biogas Utilization Sludge Digesters Digester Gas H 2S Removal Particulate & Moisture Removal Siloxane Removal Cogeneration Electricity Direct Steam Heating AWTF Buildings Treated Digester Gas Back-up Boiler Heat Recovery Another alternative to consider is the use of the biogas off site, e.g., direct injection into a natural gas pipeline, or use in compressed natural gas vehicles. In any beneficial reuse alternative the biogas requires a certain level of pretreatment prior to use. Technologies have varying requirements for pretreatment. In order from fewer to more pretreatment requirements are the internal combustion engine, turbine, fuel cell, and then off site use. The use of the biogas off site, e.g. direct injection into natural gas pipeline, or use in compressed natural gas vehicles, requires removal of carbon dioxide, in addition to reducing levels of hydrogen sulfide, water and siloxanes over what is required for powering internal combustion engines or fuel cells for power generation. Once treated to a sufficient quality, an odorant is added and the biogas is then referred to as biomethane and can be injected into a utility system natural gas pipeline. See Figure 4-7 for a schematic of the pipeline injection within the AWTF biosolids process. Biosolids Technology Assessment 31 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

45 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 4-7. Schematic of Natural Gas Injection Option for Biogas Utilization Process Heating Digesters H 2S Removal Digester Gas Upgrading System and Compression Sludge Digester Gas AWTF Buildings Biomethane To Boilers Biomethane to Natural Gas Grid Expected Energy Potential from Biogas The biogas currently being produced at CRW is expected to be typical for municipal anaerobic digesters. When high strength (with a higher biochemical oxygen demand than the biosolids) hauled waste is brought in, the quantity of the biogas will increase. Typical digester design criteria were used to estimate the potential biogas production. Summary information on the anaerobic digester design capacity and resulting biogas generation is provided in Table 4-2. The digester capacity in Table 4-2 is the theoretical capacity, and would need to include hauled waste in addition to the solids generated by the AWTF to reach the loading and biogas production rates indicated. Table 4-2. Projected Gas Generation at Facilities Plan Digester Theoretical Design Capacity TSS in Digester Feed VS in Digester Feed VS Fed/ Destruction Ratio VS Destroyed in Digesters Gas Produced Digester Gas Produced 76,900 lbs/day 61,000 lbs/day ,500 lbs/day 13.0 cf biogas per lb of VS destroyed 397,000 cfd Biosolids Technology Assessment 32 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

46 Heating Requirements for Digestion and Building Heating Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water In addition to heating the digesters, some of the heat generated by the proposed CHP system could be used to heat building spaces. Table 4-3 compares heat generated at current production rates and at the digester capacity. Building heating is not included. Table 4-3. Lean Burn Reciprocating Engine Values Current Summer (1) Current Winter (2) Capacity Summer (1) Capacity Winter (2) Biogas Generated (cf/day) 117, , , ,000 Digester Heat Required (MBTU/day) (3) Electricity Generated kwh Heat Generated (MBTU/day) Additional Heat Required (MBTU/day) Average from May to August, Average from September 2016 to April Based on average flow from May 2016 to June 2017 = MGD, Cp = 8.33 BTU/gal - ºF, and 10% heat loss An economic analysis based on the current natural gas and fuel oil pricing would need to be conducted once the CHP system is installed, and more data are gathered on the effects of hauled waste on biogas production. The analysis would determine if burning biogas to produce only heat would be economically justified rather than utilizing all of the biogas for electric production and supplementing building heat with natural gas or fuel oil. Biogas Utilization Technology Assessment Fuel Cells Fuel cells use an electrochemical process to convert hydrogen from hydrocarbons, such as methane, into electricity. As of 2015, there are 126 fuel cells in the United States, with a combined capacity of 67 MW. The average installed fuel cell has a capacity of 532 kw. The thermal energy from the fuel cells can be recovered and used for heating demands. The fuel cell is made up of three primary structures: fuel cell stack, fuel processor, and power conditioner. The cell stack generates the direct current electricity which is then used in the fuel processor to convert the fuel into a hydrogen-rich feed stream and finally the power conditioner processes the direct current electric into alternating current. There are several types of fuel cells which have been used for CHP, including phosphoric acid, molten carbonate, solid oxide, and proton exchange membrane. Fuel cells are known for achieving high efficiency levels and generating constant power when supplied an uninterrupted supply of biogas. Fuel cells typically have a power to heat ratio of 1.26, which is advantageous for systems that require more electricity than heat. Another advantage of a fuel cell is the low emissions of carbon dioxide (CO2) and even lower emissions of oxides of nitrogen (NOx). Fuel cells can produce CO2 emissions ranging from 555 to 729 lbs/mwh, whereas a typical natural gas combined cycle power plant will produce lbs/mwh. Besides less air pollution, fuel cells also do not create any noise. Currently, fuel cells have a higher capital cost per kwh than internal combustion technologies. A fuel cell can have Biosolids Technology Assessment 33 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

47 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water an installed cost ranging from $4,600 to $10,000/kWh. While fuel cells are fairly reliable, with a reported 90-95% electricity production rate, they do require periodic replacement and maintenance of their catalysts and fuel cell stacks. Fuel cells also have slow start times, ranging from 3 hours to 2 days. Fuel cells are newer and less prevalent than reciprocating engines Reciprocating Engines Another option that utilizes CHP are reciprocating engines. As of 2015, there are nearly 2,400 reciprocating engine based CHP systems in the United States. Reciprocating engines are available in sizes ranging from 10 kw to 10 MW. There are two designs for reciprocating engines: spark ignition Otto-cycle engines and compression ignition Diesel-cycle engines. The two designs are mechanically the same, but differ on the method of fuel ignition. Spark ignition uses a spark plug to ignite a pre-mixed air fuel mixture and for CHP most reciprocating engines use a 4- stroke spark ignition. Compression ignition systems rely on the elevated temperatures produced during the compression cycle, to ignite the fuel. Further, reciprocating engines are usually characterized as either rich-burn or lean-burn. Rich-burn engines operate near the stoichiometric air/fuel ratio, thus air and fuel quantities result in complete combustion, with little excess air. Lean-burn engines run at significantly higher levels than the stoichiometric ratio. Reciprocating engines have electric efficiencies that are not as high as fuel cells, ranging from 25-50% (Based on the lower heating value (LHV) of the fuel). The installation cost and maintenance cost is lower for reciprocating engines. Reciprocating engines, with proper maintenance, can be available 90-96% of the time, with a 60 second start-up time. Rich-burn reciprocating engines have a power to heat ratio of approximately 0.62 and lean-burn engines have a ratio of 0.86, as compared to the fuel cell s ratio of Reciprocating engines produce more heat than electricity. One of the most significant differences between the two CHP technologies is the emissions of criteria pollutants. Reciprocating engines emit significant amounts of NOx, carbon monoxide (CO), and volatile organic compounds (VOCs) Biogas Pretreatment Biogas pretreatment is another component that must be analyzed in relation to CHP technologies. Depending on the technology, biogas has to be treated in order to remove certain elements that can negatively impact the technology s performance. Further, pretreating the biogas can increase its heating value. Biogas from digesters is typically pretreated to remove solid particulates, siloxanes, hydrogen sulfide (H2S), and water vapor. Before the biogas can be utilized by CHP technology, it needs to be pretreated to remove certain components: H2S, moisture, and siloxanes. If not pretreated, these components can negatively impact the CHP s equipment. Biogas typically consists of 55-80% methane (CH4), 20-45% carbon dioxide (CO2), 5-10% hydrogen gas (H2), trace amounts of H2S, and other impurities. Therefore, the critical impurities are small in relation to the compounds found in biogas, but their impact is still significant if not treated. Without pretreatment, H2S concentrations vary from 50-10,000 ppm and can cause corrosion to the engine and the equipment s metal parts from the emission of sulfur dioxide (SO2) from combustion. This is especially the case if the engine is not operated continuously. Additionally, these emissions produce toxic H2S/SO2 concentrations. Common H2S removal technologies fall into one of the following categories: (1) absorption into a liquid, (2) adsorption on a solid, and (3) biological conversion. Currently, the AWTF uses the second option through the use of a Varec gas purifier that utilizes a bed of iron sponge to convert H2S into ferric sulfide deposits. The first option can result in the generation of wastewater and the third option is a commercially expensive removal process. The SO2 formed from combustion results in corrosion and results in a significant oil ph drop. By removing H2S, there is less piping and equipment corrosion and bearing damage, less oil acidification, and less oil lubricity reductions. After treating for H2S, the moisture content has to be removed. Biogas contains high amounts of moisture, and this moisture condenses when temperatures cool in piping and biogas treatment vessels. This is an issue because Biosolids Technology Assessment 34 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

48 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water engine manufacturers require no water droplets in the biogas when in the engine and that the fuel gas be less than saturated. Gas condensation can become even more of an issue in the colder weather and, besides potentially damaging the engine, moisture can collect in low spots and become an operational issue in regards to drainage and potential for freezing. Moisture can also combine with other contaminants to form corrosive substances. Therefore, it is important to remove moisture not only to prevent the aforementioned impacts, but because there are also positive impacts when moisture is removed: the efficiency of the engine increases, there is a reduction in engine oil contamination, and less corrosion of pipework and components. Typically, moisture is removed by cooling the gas to condense the water which can be drained from the system. Finally, siloxanes have to be removed. Siloxanes are silicon compounds and are found in small amounts in biogas. The prior removal of H2S and moisture will be beneficial in protecting the siloxane removal systems. Cogeneration becomes more complicated when biogas contains organic silicon compounds. The combustion inside the engine, transforms these compounds into oxides which precipitate and collect inside the machinery. Consequently, these deposits can result in breakdowns and wear down the metal parts in engine, reducing the useful lifetime of the system. Studies have found that most cogeneration engine problems involve the presence of siloxanes in the biogas. There are numerous procedures for the removal of siloxanes, however, the only industrial scale method is adsorption with activated carbon. The prior removal method, iron sponge bed, for H2S will also result inadvertently in the removal of siloxanes. Fuel cells and natural gas line injection require a more full treatment; i.e., removal of water vapor, CO2, and trace elements, in addition to those discussed above Natural Gas Pipeline Injection Another alternative for beneficial use of biogas is injecting it into a utility s natural gas pipeline. However, this process requires an advanced biogas upgrading system. The capital investment for natural gas pipeline injection can be less than a combined heat and power system. A heat source for the primary digesters would still be required if a CHP process is not utilized. Typically the biogas has to undergo treatment to remove contaminants and excessive CO2, an odorant has to be added, and finally be compressed and then sold to a local utility. It can also be used onsite as a vehicle fuel but this is very capital intensive. There is a water-wash technology available through Greenlane biogas that is ideal for grid injection and requires no heat or chemicals. It removes H2S without pretreatment and has reliable compression technology. Essentially it combines all the steps and results in a product that is pipeline acceptable. The company also claims ~99% energy available to pipeline from biogas produced. If the site requires natural gas, this would be a useful option, however, selling treated biogas as a natural gas supplement compared to utilizing the biogas to generate electricity does not appear to be economically justified. Biosolids Technology Assessment 35 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

49 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 5 Future Regulatory Trends Every component of a biosolids management program is regulated including biosolids quality, storage and application sites, and agronomic rates for beneficial use. Federal and state regulations and requirements are intended to protect surface and ground water quality and protect public health. The purpose of this section is to review the regulatory and non-regulatory pressures and drivers which impact market and business choices for biosolids management. Included are: Federal and state regulations and requirements for biosolids quality and management Agricultural requirements for application of nutrients to farms, particularly phosphorus Non-regulatory drivers such as public acceptance, odor, and sustainability demands Emerging regulations and trends which can impact the choices on business and management decisions. 5.1 Standards The United States Environmental Protection Agency (USEPA) regulates biosolids land application, surface disposal, and incineration under The Code of Federal Register Title 40 Part 503. Part 503 includes metal concentration limits, requirements for the reduction of pathogens and vector attraction, and management practices / site restrictions for land applying biosolids. Class B biosolids are specifically defined in Part 503 regulations requiring specific pathogen density and application site management. Application site management is intended to protect groundwater and surface waters from runoff or infiltration of nutrients, pathogens and metals contained in the Class B biosolids. The PADEP developed standards in the Pennsylvania Code Title 25 Chapter 271 for Class B quality and processing that parallel USEPA Part 503 regulations. Compliance with both USEPA Part 503 and PADEP Chapter 271 regulations is required for all Pennsylvania utilities. 5.2 Pollutants To meet Class A/EQ standards identified in Pennsylvania Code Title 25, , the pollutants shall never exceed the ceiling limits and the average shall never exceed the monthly average concentration limits defined in tables therein. To meet Class B standards, the concentration of any pollutant must not exceed the ceiling concentrations, but do not need to comply with the monthly average concentrations. Table 5-1 summarizes prescribed ceiling and monthly average concentrations. Future Regulatory Trends 36 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

50 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 5-1. Biosolids Pollutant Concentrations Limits 1 Contaminant Arsenic 75 Cadmium 85 Ceiling Concentration (mg per kg) 2,3 Monthly Average Concentration (mg per kg) 2 Copper 4,300 1,500 Lead Mercury 57 Molybdenum N/A Nickel PCBs 86 4 Selenium 100 Zinc 7, , Source: Pennsylvania Code Title 25, (b)(1) Ceiling Concentration, (b)(3) Monthly Average Concentration 2. Dry weight basis 3. These values are a maximum levels, not to be exceeded. The biosolids generated at the AWTF consistently meet the pollutant limits under Pennsylvania Code Title 25 Chapter , as summarized in Table 5-2. Note that the AWTF biosolids consistently meet the more stringent Monthly Average Concentration limits in Table 5-1, although Class B biosolids are not required to meet these limits. CRW is encouraged to continue to meet the higher quality standards. Future Regulatory Trends 37 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

51 Arsenic Cadmium Copper Lead Mercury Molybdenum Nickel PCB's Selenium Zinc Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 5-2. CRW 2015 Pollutant Analyses Summary Sample Result, mg/kg Sample Data 1/15/2015 <9.6 < <0.31 <24.0 1,860 3/3/2015 <9.9 < <0.43 <24.7 1,750 5/7/2015 <9.1 < <0.41 <22.6 1,370 7/13/2015 < <21.4 1,540 9/15/2015 <8.1 < <0.16 <20.2 1,670 11/24/2015 <10.4 < <0.19 <26.0 2,040 1/27/2016 < <0.29 <20.1 1,810 3/16/2016 <9.4 < < <0.24 <23.6 1,320 6/8/2016 < <0.22 <20.4 1,720 7/12/2016 <8.6 < <.015 <21.5 1,230 9/22/2016 < <23.0 1,270 Maximum < <26.0 2, Pathogen Reduction There are three general alternatives for compliance with Class B pathogen reduction (PR), as required under 25 PA Code : Alternative 1 - Demonstrate < 2,00,000 MPN or coliform-forming units (CFU) of fecal coliforms per gram of total solids; Alternative 2 - Apply a Process to Significantly Reduce Pathogens treatment; or Alternative 3 - Apply a process that is equivalent to a Process to Significantly Reduce Pathogens, as determined by USEPA. There are five Processes to significantly reduce pathogens (PSRP), which include aerobic and anaerobic digestion, air drying, composting and lime stabilization. The only alternative that applies to the AWTF is the anaerobic digestion PSRP which requires that: sewage sludge is treated in the absence of air for a specific mean cell residence time at a specific temperature. Values for the mean cell residence time and temperature shall be between 15 days at 95 ºF to 60 days at 68 ºF. This PR alternative is available to CRW, although is not currently used for compliance purposes. With the completion of biosolids facilities improvements, the second primary digester will be operational, the heat exchangers will be rehabilitated, and the facility should be capable of consistently meeting the time and temperature PSRP requirements. Future Regulatory Trends 38 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

52 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water PR requirements are satisfied by CRW in accordance with the criteria under 25 PA Code (b)(3) [Class B - Alternative 2], Fecal Coliform. As such, the Fecal Coliform test must be conducted on a series of at least seven (7) samples during a monitoring event and the geometric mean calculated. The results of all such testing confirm that the AWTF processed solids meet the standards established for Class B biosolids. Testing results show that the geometric mean of Fecal Coliform of the anaerobically stabilized biosolids is consistently less than 2 million colonies per gram of total solids (dry weight basis). Table 5-3 provides a summary of the Fecal Coliform data collected throughout 2015 and 2016 showing that the geometric mean of the Fecal Coliform test is less than 2 million CFU per gram of dry solids for the dewatered biosolids. Table 5-3. AWTF Historical Pathogen Reduction Monitoring Summary Monitoring Period Sample Date Sample Number / Units colony forming units per gram of dry solids Geometric Mean (CFU/g dry solids) Jan/Feb 1/15/15 11,800 14,100 17,600 15,900 12,600 23,200 13,600 15,173 Mar/Apr 3/3/15 3,700 2,280 2,780 8,720 4,410 1,830 2,290 3,244 May/Jun 5/7/15 3,090 2,430 10,000 3,300 2,570 2,090 3,050 3,277 Jul/Aug 7/13/ Sep/Oct 9/15/15 133, ,000 48,100 29,500 51,300 38,100 41,800 59,439 Nov/Dec 11/24/15 23,800 17,500 24,800 18, , ,000 18,200 34,541 Jan/Feb 1/27/16 5,790 4,720 6,380 7,910 6,700 6,090 12,200 6,820 Mar/Apr 3/16/16 12,900 11,100 8,620 7,180 11,800 5,050 7,510 8,762 May/Jun 6/8/16 12, ,000 13,000 10,700 11,200 13,300 10,800 17,654 Jul/Aug 7/12/16 10,700 14,600 20,000 14,100 21,400 10,900 15,300 14,823 Sep/Oct 9/22/ , , , , , ,000 25, Vector Attraction Reduction There are eleven options specified in the regulation for vector attraction reduction (VAR) that relate to solids generated from wastewater treatment. The application of VAR options depends on the type of biosolids and the disposal/reuse method, and is an indication of the level of stability. Options 1 through 8 relate to treatment processes (process VAR), and Options 9 and 10 relate to injection or incorporation within 6 hours of application, respectively (barrier VAR). For land application programs, meeting process VAR is necessary to comply with farm conservation plan requirements (related soil erosion) and the ability to store at the farm. The only process VAR option that applies to CRW is Option 1, which requires volatile solids be reduced by a minimum of 38 percent. Future Regulatory Trends 39 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

53 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water VAR requirements are achieved through anaerobic digestion and is satisfied in accordance with the criteria under 25 PA Code [Option 1]. Option 1 requires a minimum of 38% reduction in the Volatile Solids (VS) across the digestion facilities. Analyses for VS are taken on samples entering and exiting the Primary Digester. Inflow VS (VSin) are sampled from the thickener underflow and outflow VS (VSout) are sampled from sampling port on the belt filter press feed line. VS Reduction (VSR) analyses and calculations are performed several times per month. The Van Kleeck method is used to calculate the overall VS reduction. Table 5-4 provides a summary of the VSR data collected throughout 2015 and 2016 showing that the VSR is typically above the 38% necessary to demonstrate VAR is achieved. With process changes associated with the BNR facilities start-up in April 2016, however, VSR was close to and below the 38% required to meet Option 1. Material Matters, Inc. (MMI) worked with CRW personnel to undertake several measures to improve digester performance and closely monitor digester operations data. It is recommended that CRW continue to monitor VAR closely, until the digester improvements have been completed. Table 5-4. CRW Historical Vector Attraction Reduction Monitoring Summary Monitoring Period VSin VSout VSR Jan/Feb 2015 Mar/Apr 2015 May/Jun 2015 Jul/Aug 2015 Sep/Oct 2015 Nov/Dec 2015 Jan/Feb 2016 Mar/Apr 2016 May/Jun 2016 Jul/Aug % 62.1% 64.1% 78.7% 57.9% 62.8% 78.0% 58.9% 59.6% 81.4% 60.7% 64.8% 80.8% 66.1% 53.7% 81.2% 67.0% 52.9% 81.2% 64.0% 59.0% 80.7% 60.6% 63.3% 77.4% 62.5% 51.3% 74.2% 64.6% 36.5% 5.5 Biosolids Management All utilities that generate and land apply biosolids in Pennsylvania must follow the general requirements, management practices, and operational standards found in 25 PA Code Chapter , Management Practices. General Permit All facilities that generate Class B biosolids and plan to land apply must apply for coverage under the state-wide General Permit (GP). Once a Notice of Intent (NOI) application is submitted to PADEP for coverage under the GP, the PADEP reviews the submittal and ultimately issues a Notice of Coverage. The GP for the Land Application of Non-Exceptional Quality Biosolids (Class B) PAG-08, was issued by PADEP on April 3, 2009 and was effective from April 3, 2009 through April 2, The PADEP has administratively extended the PAG-08 GP through April 2, PADEP has indicated that the GPs will be renewed during 2017, and new phosphorus management and hauled waste requirements will be included in the GPs. Future Regulatory Trends 40 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

54 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Land Application 30-Day Notice New land application sites for beneficial use of Class B biosolids must be approved by PADEP, which has 30 days to review the application. Class A/EQ biosolids are exempt from this requirement. The land applier must provide the detailed information necessary to determine if a proposed application site is appropriate for land application of biosolids. Detailed information about the site includes, but not limited to: types of crops, how agronomic rates will be calculated, methods of application, landowner agreements, and a detailed map that identifies all setbacks and land application areas. Recordkeeping Recordkeeping for Class B biosolids is more comprehensive than Class A/EQ biosolids. As with Class A/EQ, biosolids quality, including pollutants, PR and VAR processes, and the corresponding certification statement must be reported. However, unlike Class A/EQ biosolids, the facility must also report a summary of biosolids applied to each field, the number of acres that received biosolids, and the type of crop, projected yield, and nitrogen requirements where biosolids were applied. Additionally, the pollutant loading rate for each farm field must be calculated annually and added to biosolids pollutants applied in past applications (cumulative pollutant loading rate or CPLR). The facility must also indicate how public access was restricted from the site. Land Application Requirements Class B biosolids must be land applied at an agronomic rate to provide the amount of available nitrogen needed by the crop or vegetation in the application area. The nitrogen need is based on two factors: the type of crop and the projected yield. The projected yields must be realistic and based on site-specific factors. Using five-year historic site yields is typical and recommended; however, recommendations by the farmer, written recommendations from the Pennsylvania State University (PSU) extension, and the county yield average can be used if historic site yields are not available. To calculate the amount of biosolids needed to meet crop needs, it is necessary to calculate the amount of plant available nitrogen (PAN) available in the biosolids, which is dependent on the mineralization rate of the biosolids nitrogen. Land application of Class B biosolids on agricultural land, forest, and reclamation sites are subject to setbacks around streams, sinkholes, dwellings, and water sources, but are not required for Class A/EQ biosolids. These management practices are found under 25 PA Code Title Chapter Additionally, biosolids may not be applied within 11-inches of the seasonal high water table nor within 3.3-feet of the regional groundwater table. Agricultural utilization cannot be conducted on slopes that exceed 25% or where soil ph is less than 6.0. Land appliers must also complete training courses sponsored by PADEP within one (1) year of beginning to conduct land application operations. 5.6 Regulatory and Non-Regulatory Drivers There are several regulatory and non-regulatory drivers that could potentially affect biosolids land application programs including limiting phosphorus application, odor considerations, and farmland availability. There are no federal biosolids regulatory changes planned; however, PADEP plans revisions to the GPs to be reissued in Phosphorus Management The nutrients supplied by biosolids are not present in the same ratio as they are required by plants. Therefore, biosolids supplied at an agronomic rate for nitrogen supply an excess of some nutrients, especially phosphorus. When applied to meet crop nitrogen needs, biosolids supply large quantities of phosphorus. In soils that already Future Regulatory Trends 41 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

55 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water have high phosphorus content, application of phosphorus can increase the potential for phosphorus loss from the field through runoff to surface waters, causing eutrophication. Indications are that PADEP will pursue phosphorus management through the phosphorus index (P-Index) as part of the upcoming reissued GPs. The P-Index is a tool used to assess the potential for phosphorus to move from agricultural fields to surface water. It uses an integrated approach that considers soil features, as well as soil conservation and phosphorus management practices in individual fields. In a study conducted on biosolids application farms, MMI found that: " implementation of the P-Index will have a significant impact on land application of biosolids in Pennsylvania. However, it appears that the Pennsylvania P Index contains sufficient flexibility for landappliers to credit biosolids characteristics and practices to reduce the risk of P loss, and maintain effective land application programs. Of the 46 fields included in this study, use of the P Index allowed for 35 fields to continue with nitrogen management (76% of the fields), seven with phosphorus management, and one field would be excluded from biosolids applications. One conclusion from the study noted that biosolids programs should be able to accommodate phosphorus management, but land application practices must evolve to meet the challenge. CRW should periodically have a phosphorus source coefficient test performed by PSU Analytical Labs as part of routine monitoring. The results of this analysis will be utilized in the future in site index calculations if phosphorus management is implemented by PADEP. CRW may also want to consider conducting an assessment of their current qualified acreage to determine the impact of phosphorus management. Hauled Waste Acceptance PADEP Central Office staff have indicated that the Department intends to incorporate hauled waste conditions in the upcoming reissued GPs. While the exact language and requirements are unknown at this time, these revisions may potentially impact either CRW s biosolids land application program and/or its hauled waste program. Odor Nuisance odors from land application sites are the primary source of public opposition for biosolids recycling (USEPA Biosolids and Residuals Management Fact Sheet- Odor Control in Biosolids Management. Office of Water. September Washington, D.C). According to a 1999 Biocycle nationwide survey, nuisance odors at a land application site are usually the initial operating problem leading to public opposition. Nuisance odors created by biosolids are detrimental to aesthetics, property values, and the quality of life in an area. Therefore, if a utility fails to acknowledge the potential for product odor, unintended odors can result in adverse public relations including non-acceptance, complaints, and even a shutdown of the biosolids recycling program (USEPA 2000). Treatment technologies are most effective if designed with odor reduction in mind. The proposed rehabilitation as part of CRW s biosolids facilities improvements should improve digester performance and VSR, thereby reducing VS of the final biosolids product. Reducing the VS content of the dewatered biosolids produces a more stable product and minimizes nuisance odors. Farmland Availability and Demand for Product Farmland availability and demand for the biosolids product is critical when evaluating the end use options. CRW currently has over 700 acres qualified for biosolids land application of their Class B biosolids and MMI recommends that CRW add 230 more acres to the program (approximately two new farms). Central Pennsylvania contains many farms that are located within 50 miles of the CRW AWTF which provides opportunities with relatively low transportation costs. Biosolids often compete with animal manures and litters as a nutrient supplement. Additionally, Future Regulatory Trends 42 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

56 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water biosolids imported from outside the region (i.e. Philadelphia, Maryland, New York, and New Jersey areas) produces competition for farmland. While ample farmland is available throughout the region, pressure from manures and imported biosolids is increasing. CRW should continue to work with the existing farmers in its program to deliver high quality biosolids with low odors that supply cost effective nutrients for their farms, as well as search for additional acreage and farmers to add to the program. Future Regulatory Trends 43 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

57 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 6 Summary of Improvement Plan 6.1 Biosolids Facility Overall Improvements WRA has evaluated the biosolids treatment process and has determined there are beneficial changes that can be made to the biosolids facilities to allow CRW to better attain their goals. Recommendations include the following major modifications: Separately Thicken Waste Activated Sludge and Primary Sludge This process modification has been proven at many facilities to greatly increase the percent solids in the thickened sludge sent to the anaerobic digesters. The current practice of co-thickening sludge at the AWTF is averaging approximately 3% solids (feed to the primary digesters). Separate thickening of primary and WAS is expected to result in 4-6% solids in each sludge stream. This in turn will increase the solids retention time in the anaerobic digesters, which will increase volatile solids reduction, increase biogas generation, and reduce the quantity of digester gas required to heat the sludge. WAS thickening with Gravity Belt Thickeners (GBTs) is recommended. The GBTs will be installed in a new building adjacent to the existing primary clarifiers. A thickened WAS blending tank will be constructed adjacent to the new building, where thickened primary sludge will be blended, resulting in a continuous feed to the digesters. Increase Utilization of the Existing Anaerobic Digesters Based on current and design (37.7 MGD) flows and loads, only one of the two primary digesters is needed. With the expected decrease in required volume from separate sludge thickening, there will be additional capacity in the digesters. This additional available capacity can be utilized by accepting hauled waste, e.g. food processing waste. In 2017, CRW began experimenting with feeding hauled waste to the anaerobic digesters. Based on the current and projected capacity of the anaerobic digesters, there is an opportunity to expand the receipt of hauled waste, with the goal of generating additional biogas and revenue. A hauled waste receiving station is recommended. The receiving station will be constructed in the new WAS thickening building. The receiving station will screen the hauled waste and remove grit prior to being discharged to an equalization tank adjacent to the WAS thickening building. The hauled waste will be blended with the combined primary sludge and WAS to target a uniform feed consistency to the digesters. Combined Heat and Power Generation With the improved digester efficiency, along with the increase in hauled waste and the resulting increase in biogas, there is an opportunity to better optimize heat and electrical power recovered from the biogas generated. A combined heat and power station would provide an opportunity to improve the overall energy recovery efficiency. Two new 500 kw reciprocating internal combustion engine driven generators are recommended. They will be installed in the existing cogeneration building. As the hauled waste program becomes more established, a third generator could be installed. The electricity generated will be put back on the utility grid through a new transformer. Biogas pretreatment equipment will be installed upstream of the generators to better control the gas quality to the units and decrease the maintenance required. The biogas pretreatment and heat recovery equipment will be located within, on the roof of, and adjacent to, the cogeneration building as needed. Summary of Improvement Plan 44 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

58 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Anaerobic Digestion Improvements The planned improvements to the primary digesters are necessary to provide reliability and efficiently handle the increased sludge solids concentration and the hauled waste. These improvements include: Gas mixing system replaced with mechanical mixing system Replacement of the primary digester fixed covers Replacement of the gas and sludge piping internal to the digesters Replacement of sludge piping and valves within the digester control house gallery Replacement of the waste gas flare Replacement of the primary digester recirculation pumps Replacement of primary digester transfer pumps Provisions for future direct steam injection to the digesters New electrical and controls building Mineral buildup in the digester recirculation line and heat exchanger has also been an operational difficulty. It is believed the mineral is vivianite, (i.e. solid hydrated iron phosphate), which provides limited economical options to address. As an alternative, the direct steam injection heating of the digesters is recommended. This will require a steam boiler, either from the CHP system, or the replacement boiler in the boiler building would be outfitted to generate steam and steam headers, to be installed in the digesters. Provisions for the steam lances will be included in the primary digester improvements. Direct steam injection in the sludge feed line, and the recirculation lines will be included in the future. The secondary digesters are currently used as digested sludge settling tanks prior to dewatering. With the expected increase in digested solids concentrations from separate thickening of primary and WAS sludge, this settling of digested sludge will not be necessary. One of the secondary digesters could be converted into a third primary anaerobic digester. This would require similar upgrades as the primary digesters, listed above. Direct steam injection would also be applied in the converted secondary digester. In addition, a recirculation loop would be recommended to provide further homogenization of the solids in the tanks. Another alternative is to keep both as secondary digesters and retrofit them with linear motion mixers to allow a more consistent feed to dewatering. Hauled waste can have an adverse effect on the digesters due to large variations in volume and characteristics. Equalization tanks can help provide for a more consistent feed to the digesters and one equalization tank is recommended to be included with the hauled waste receiving system. As a further improvement in anaerobic digester performance and gas production, the addition of an acid phase digester should be considered. One of the widely reported benefits of acid phase digestion is the reduction in foaming events, like those caused by inconsistent feed to the digesters. Figure 6-1 shows a schematic of the recommended biosolids improvements plan. Summary of Improvement Plan 45 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

59 Figure 6-1. Schematic of Recommended Biosolids Improvements Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Waste Activated Sludge Gravity Belt Thickeners Gas Storage Sphere Biogas Pre-Treatment Combined Heat and Power Waste Flare Diluent Water Blending Tank Polymer Hauled Waste Primary Sludge Unloading With Rock Trap Gravity Thickeners Screen Equalization Tank Acid Phase Digester Primary Anaerobic Digesters Secondary Anaerobic Digesters Belt Filter Presses FUTURE: Centrifuge or similar Biosolids Storage Land Application A site plan of the proposed improvements is shown on Drawing 01. Summary of Improvement Plan 46 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

60 Whitman, Requardt & Associates, LL 801 South Caroline Street, Baltimore, Maryland 21231

61 6.2 Specific Facility Recommended Improvements Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Included in this section is a summary of design criteria for the recommended facilities, and key details for the individual facilities. A summary of the recommended biosolids facilities improvements, including key design criteria, are included in Table 6-1. Table 6-1. Recommended Improvements by Facility Gravity Thickeners Hauled Waste Receiving Station WAS Thickening Primary Digesters Two Phase Digestion Secondary Digesters Rehabilitation Secondary Digester Upgrade Sludge Dewatering Replace Sludge Mechanisms Replace Sludge Pumps, VFD Replace Scum Pumps New Building with WAS Thickening New Receiving Station 600 gpm Unloading Rate Screening, Grit, and Grease Removal 75,000 gal Holding Tank Hauled Waste Transfer Pumps 3 New 2 m Gravity Belt Thickeners 600 gpm Hydraulic Loading Rate Each 2 In Operation 16.5 hrs/day at Design Capacity New Building with Hauled Waste 100,000 gallon Blending Tank Sludge Transfer Pumps Replace Mixing System with Mechanical Mixer Replace Gas a Sludge Piping Inside the Digester and Inside the Control Building New Electrical and Controls Building Replace Waste Gas Flare Replace Recirculation Pumps Replace Transfer Pumps Install Provisions for Direct Steam Injection into Digesters Capacity after Upgrades and with WAS Thickening will be 61,000 lbs VS/day Install One (1) 300,000 gallon Acid Phase Digester 1.5 Days SRT Replace Roof on Both Digesters Replace Piping Refurbish Concrete and Exterior Brick Upgrade One Existing Digester to Function as a Primary Digester with Mechanical Mixer, and Recirculation with Temperature Control. Install Mechanical Mixer on One Existing Digester Two (2) New Centrifuges Hydraulic Loading Rate, 110 gpm each Solids Loading Rate, 2,000 lbs dry solids/hr each Summary of Improvement Plan 48 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

62 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 6-1. Recommended Improvements by Facility Boiler Building Cogeneration Building Gas Collection, Storage and Pretreatment Sludge Storage Sheds One (1) New Steam Boiler in Existing Building Two (2) New 500kW Biogas Reciprocating Engine Drive Generator Units, with Provisions for a Third Unit Combined Heat Recovery Replace Two (2) Low Pressure Compressors Replace Hydrogen Sulfide Removal Unit Replace Particulate and Condensate Removal Unit Existing Storage Tank One (1) New 15,000 cu ft Capacity Sludge Storage Shed Gravity Thickener Facilities Primary sludge will be thickened in the existing gravity thickeners without waste activated sludge (after implementation of WAS Thickening). The overflow rate of the thickeners was evaluated to determine if the rate when thickening only primary sludge is too low. The primary sludge flow rate has averaged 0.44 MGD over the period studied. Thickening this stream separately with a 4:1 dilution water to sludge ratio would result in an overflow rate of 220 gal/sq ft/d, which is low and subject to floating sludge, odors and septicity. Operating one thickener would be recommended to keep the dilution water quantity reasonable, result in an overflow rate of 440 gal/sq ft/d, and avoid excessive detention time. Also, chlorine can be added to reduce odors and maintain fresher sludge with less septicity and reduce potential for gasification. With the separate thickening of WAS, the existing gravity thickeners are expected to thicken the primary sludge to 4-6% solids. Since the gravity thickeners are well beyond their expected life, the sludge mechanisms and sludge and scum pumps will need to be replaced within the planning horizon of the biosolids improvement plan. The pumps and mechanism will be replaced in kind. Hauled Waste Facility Hauled waste will be delivered in tanker trucks varying in size. Handling the hauled waste will require unloading, pretreatment, flow equalization, blending with thickened primary and waste activated sludges, and pumping to the digesters. Equalization of the hauled waste reduces the potential for foaming and upset conditions as there may be considerable variability in waste volumes and characteristics. The hauled waste facility would include the following components, at a minimum. Truck unloading station with containment Automated billing ticket generation Rock trap One (1) screening washing unit with bypass for grease One (1) grit trap with grease removal system One (1) transfer pump One (1) equalization tank, both totaling to a working volume of one (1) times the daily expected volume Tank aeration/mixing system with odor control Two (2) transfer pumps to convey pretreated waste to the primary digesters Summary of Improvement Plan 49 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

63 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The mechanical equipment for handling hauled waste would be housed in the same building as the proposed WAS thickening process. Additional pretreatment equipment may be necessary depending on the characteristics of the hauled waste anticipated to be accepted by the AWTF. The hauled waste truck unloading station will be equipped with an automated dump station control panel. The panel will read the driver s access card, then open an automated valve, and record the totalized flow from a flow meter. This information will be stored in the panel and can be communicated across a network or downloaded for billing purposes. The truck will connect to an unloading station with a hose. The hauled waste will be pretreated during the truck unloading operation for the removal of inorganics (grit and screenings). Hauled waste may also include fats, oils and grease (referred to as FOG) which will bypass the screening operation. Screenings will be washed, compacted and conveyed into a dumpster. The grit that is removed will also be conveyed into the same dumpster. Table 6-2 shows key design criteria for the hauled waste receiving station. Table 6-2. Hauled Waste Receiving Station Quantity 1 Hydraulic Capacity 1.37 MGD Drum Screen Diameter 47 inches Screen Openings Screenings Compacted Water Content Location Rating 1/4 to 3/8 inch 65%, maximum Class 1, Division 2 Hauled waste will be pumped into a holding tank to provide flow equalization prior to being blended with primary sludge and WAS and pumped into the primary anaerobic digesters. The flow equalization tank will have a working volume equal to one day of expected hauled waste volume. The tank will be agitated with coarse bubble diffusers and equipped with an odor control system. Hauled waste transfer pumps will pump from the hauled waste holding tank to the sludge blending tank and then to either of the primary anaerobic digesters, normally through the direct steam injection system in the recirculation loop, so the combined sludge could be heated prior to entering the digester. The hauled waste receiving station will be installed in the waste activated sludge thickening building. See Drawings 02 and 03 for a conceptual floor plans of the lower and upper levels of the proposed building showing the hauled waste receiving equipment. Summary of Improvement Plan 50 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

64 Whitman, Requardt & Associates, LLP 801 South Caroline Street, Baltimore, Maryland 21231

65 Whitman, Requardt & Associates, LLP 801 South Caroline Street, Baltimore, Maryland 21231

66 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Waste Activated Sludge Thickening Facility Gravity belt thickeners will be installed for the separate thickening of WAS. The GBTs will be sized to operate 12 to 18 hours per day, 7 days a week with the preliminary design criteria in Table 6-3. Table 6-3. Gravity Belt Thickeners GBT Units No. of Units Hydraulic Loading, design Belt Width Hydraulic Capacity Solids Capacity Operating Schedule, each Volume of WAS, total Volume of thickened WAS, total 3, in parallel 300 gpm/meter of belt width 2 m, each 600 gpm, each 1,000 lbs/hr, each 16.5 hrs/day with 2 units in operation, 7 days a week 1,200,000 gpd 1,200 gpm when operating 50,000 gpd 56 gpm when operating Blending a portion of the thickened primary sludge with the WAS will improve the solids capture of the gravity belt thickener. Provisions in the piping should be considered to allow for this flexibility. The thickened WAS will be pumped to a blending tank to provide flow equalization and mixing with thickened primary sludge and hauled waste prior to being pumped into the primary anaerobic digesters. The blending tank will have a working volume equal to 100,000 gallons. The tank will be covered and agitated with coarse bubble diffusers. Digester feed pumps will pump from the blending tank to either of the primary anaerobic digesters, normally through the heat exchanger recirculation loop, so the digester feed could be heated prior to entering the digester. The wasting of RAS, rather than MLSS, has also been examined. If RAS is utilized, the volume of sludge will be reduced to 50-60% of the MLSS related volume, or a range of 0.6 to 0.72 MGD rather than 1.2 MGD. If this change is made before the construction of the GBT facility, then the GBT sizing could be modified to 3 units, with a belt width of 1.5 meters each. Thus, the belt width of 2 meters as shown in Table 6-3 would change to 1.5 meter. Reducing the size of the GBTs further is not recommended to allow for greater flexibility when wasting volumes increase during periods of higher than average wasting, e.g., during the spring when reducing the target MLSS. See Drawing 01 for a site plan of the proposed WAS thickening and hauled waste receiving building. See Drawings 02 and 03 for conceptual floor plans of the lower and upper levels of the proposed building, showing the gravity belt thickener and related equipment. Sludge Blending Tank A new sludge blending tank will be provided to blend the thickened WAS, and the hauled waste. Thickened primary sludge will also be pumped to the proposed blending tank. Providing a blending tank in addition to the hauled waste tank will allow for the isolation of unloaded hauled waste, if necessary, and for control of the ratio of hauled waste, thickened WAS and thickened primary sludge that is pumped to the digesters. The blending tank Summary of Improvement Plan 53 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

67 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water will be a cast in place concrete tank with common wall construction with the hauled waste tank. The blending tank will be covered and mixed. Key design criteria are presented in Table 6-4. Table 6-4. Sludge Blending Tank No. of Units Working Volume Length and Width Side Water Depth 1 100,000 gallons 40 feet by 28 feet 12 feet Primary Digesters and Control House The refurbishment of the primary digesters and associated upgrades is currently being implemented. Improvements will include: Gas mixing system replaced with mechanical mixing system Replacement of the primary digester fixed covers Replacement of the gas and sludge piping internal to the digesters Replacement of sludge piping and valves within the digester control house gallery Replacement of the waste gas flare Replacement of the primary digester recirculation pumps Replacement of primary digester transfer pumps New electrical and controls building The primary digester concentric tube heat exchangers are not being modified with the current project. The heat exchangers are sufficiently sized for the digester operation when not fouled with mineral buildup. Currently, the heat exchangers get too fouled to maintain digester temperature within months of operation. The heat exchangers will be replaced by the direct steam injection into the digesters. A steam boiler will eventually be installed in the existing boiler building to replace the existing hot water boilers. Steam distribution piping will be extended to the floor of the digesters and steam will be distributed through a series of nozzles. Once the primary digesters refurbishment is completed, both digesters will be put in operation to provide additional solids and gas production capacity. The secondary digesters will remain as holding tanks until the capacity is needed, but will need to be refurbished with new covers and new process piping as a course of maintenance to replace aged infrastructure. When the two existing primary digesters are approaching capacity, CRW will need to determine if one of the secondary digesters should be converted to a primary digester and a new acid phase digester tank should be constructed. Conversion of a secondary digester to a primary digester will require similar upgrades to those of the existing primary digesters. Converting a secondary digester to a third primary digester and construction of an acid phase digester depend on the viability of a sustained hauled waste program and other economic factors described in Section 7.4. A new separate acid phase digester tank would be sized for a solids retention time of 1-2 days, where the acid formation phase of digestion would primarily take place. The feed biosolids would be pumped through a heat exchanger to mesophilic temperatures, and into the acid phase tank. The low-ph environment would be established Summary of Improvement Plan 54 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

68 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water in this digester, suspended solids would be hydrolyzed, and fatty acids would be formed. The sludge from the acid phase digester would be pumped into the main digesters which can be operated to maintain optimum environment for methanogenic bacteria formation. Table 6-5 summarizes design criteria for acid phase digestion. Table 6-5. Acid Phase Digester No. of Units Volatile Solids Loading, design SRT, Design Working Volume Height to Diameter Ratio Diameter Side Water Depth lbs volatile solids/cu ft/day 1.5 days 300,000 gallons 1.2:1 to 1.5:1 35 feet 45 feet See Drawing 01 for the site plan indicating the proposed location for the acid phase digester. Secondary Digesters and Control House The secondary digesters are currently operated as holding tanks for storage and equalization of digested sludge prior to being pumped to dewatering operations. The secondary digesters need to be refurbished with new covers and new process piping as a course of maintenance to replace aged infrastructure. If the quantity of hauled waste and sludge generated at the AWTF exceeds the capacity of the existing primary digesters, one of the secondary digesters can be converted to operate as an anaerobic digester. As mentioned above, the conversion would require similar upgrades to those currently being implemented for the primary digesters. Providing mechanical mixing in both secondary digesters should be considered to provide a more uniform feed to the dewatering facilities. The design criteria of the existing secondary digesters are presented in Table 6-6. Table 6-6. Secondary Digesters No. of Units Clean Tank Volume Roof Type Diameter Side Water Depth 2 924,000, and 839,000 gallons One (1) Fixed, One (1) Floating 85 feet 28 feet Summary of Improvement Plan 55 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

69 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Dewatering Facilities The existing dewatering facilities are anticipated to meet the needs of the Biosolids Facility Improvement Plan, including the hauled waste projections. The most significant disadvantage of the belt filter press (BFP) technology for the AWTF is that the dry cake solids are lower than typically produced by some of the other technologies, such as centrifuges or screw presses. Rather than replace the relatively new BFPs to increase the cake solids, it is recommended to investigate improvements to the BFP operation such as: Modifications to polymer conditioning Improve the digested sludge degree of stabilization and characteristics Review the belt filter press condition and operation In addition, pretreatment technologies should be investigated, such as the SLG (Solid Liquid Gas) process by Orege. A separate study is being undertaken to investigate alternatives to optimize dewatering operations. Local biosolids regulations are likely to become more stringent in the foreseeable future, i.e., 5-10 year timeframe. There may be more reporting requirements, a higher quality of biosolids required for land application, and restrictions on land available for application. While these changes in regulations are developed and finalized, a reasonable course of action is to continue utilizing the existing belt filter presses. As more stringent biosolids disposal regulations become implemented in the future, the production of Class A biosolids should be considered. Boiler Building The existing hot water boilers would be replaced with one (1) 6,000,000 BTU/hr steam generating boiler to provide supplemental heat to that from the CHP units. The boiler would be dual fuel capable of burning either biogas or propane. Cogeneration Building The use of a combined heat and power system will provide higher energy recovery efficiency than the existing separate system. Considering that both the existing boilers, and engine driven generators are beyond their expected life, and if CRW decides to implement and expand hauled waste acceptance, investing in a combined heat and power system is recommended. The reciprocating engine driven generator is well known to the AWTF operations staff and is projected to provide an economic benefit to the facility. Therefore, it is recommended that the AWTF plan to install a lean burn reciprocating engine based CHP system. The amount of projected biogas is based on typical values for municipal biosolids anaerobic digestion. This implies that the biogas generated from the anticipated hauled wastes will average similar values to that of the biosolids. In fact, the actual blend of hauled waste may vary significantly over time, as will the ratio of hauled waste solids to biosolids. Therefore, the amount projected biogas will have a large variation over time. Therefore, the CHP system should be designed to provide for significant flexibility. Manufacturer s generally carry a nominally sized 500 kw continuous rated 3 phase 60 Hz biogas fueled generator. Assuming a hauled waste program is pursued as recommended, and considering redundancy and turn down flexibility, three (3) 500 kw units would be recommended. Preliminary sizing based on catalog information would indicate that the three units could fit in the existing cogeneration building. Pretreatment equipment, and some of the heat recovery equipment would be installed adjacent to, or on the roof of, the building. The 480V power that is provided by the generator is stepped up to medium voltage prior to connecting to the utility power lines by a transformer. The existing transformer would need to be replaced, as would the cables from the cogeneration building to the utility power lines. Summary of Improvement Plan 56 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

70 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Vivianite Management Vivianite buildup will be mitigated through the direct steam injection heating of the digesters. See above sections for discussions on the steam heating of the digesters and steam generation. Sludge Storage Sheds The existing sludge storage sheds are in good physical condition, and will provide many years of service with continued maintenance. The steel columns should be repainted and the metal roof replaced as needed. Due to the doubling in digested sludge that will be produced from the aforementioned upgrades including hauled waste co-digestion, and the need for additional storage when sludge cannot be moved off-site, due to either weather or unintended circumstances, a new sludge storage shed is proposed. Its location and approximate size can be seen in Figure 6-2. Table 6-7 shows the design criteria for the proposed storage shed. Table 6-7. Proposed Storage Shed Area, Dimensions Sludge Height Sludge Density Sludge Production Rate, design Detention Time 2600 sq ft, 52 x 50 ft 6 ft 64.3 lb/cf 52,000 lbs TSS/day (including hauled waste) 19 days Due to space constraints, the tipping scale will need to be relocated to accommodate the new storage shed. Its proposed location can also be seen in Figure 6-2. This new location will result in rerouting the trucks to go in a counter-clockwise direction when entering the facility. Summary of Improvement Plan 57 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

71 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Figure 6-2. Proposed Storage Shed Gas Collection, Storage and Pretreatment The gas compressors and pretreatment system are beyond their useful life expectancy, and are not designed for the flow or pressure required by the CHP system, and therefore the compressors will be replaced. Before the biogas can be utilized by CHP technology, it needs to be pretreated to remove certain components: H2S, moisture, and siloxanes. If not pretreated, these components can negatively impact the CHP s equipment. Without pretreatment, H2S concentrations vary from 50-10,000 ppm and can cause corrosion to the engine and the equipment s metal parts from the emission of SO2 from combustion. This is especially the case if the engine is not operated. Additionally, these emissions produce toxic H2S/SO2 concentrations. Currently, the AWTF uses the second option through the use of a Varec gas purifier that utilizes a bed of iron sponge to convert H2S into ferric sulfide deposits. It is a simple system that requires limited operational oversight. A larger replacement iron sponge system will be installed for the proposed CHP system. Biogas is typically saturated with water, and after treating for H2S, the moisture content has to be removed. The efficiency of the engine increases, there is a reduction in engine oil contamination, and less corrosion of pipework and components. Moisture will be removed by cooling the gas to condense the water which can be drained from the system. Summary of Improvement Plan 58 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

72 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Siloxanes are silicon compounds and are found in small amounts in biogas. Combustion inside the engine, transforms these compounds into oxides which precipitate and collect inside the machinery. Consequently, these deposits can result in breakdowns and wear down the metal parts in engine, reducing the useful lifetime of the system. The only industrial scale method of removing siloxanes is adsorption with activated carbon. The activated carbon siloxane removal system will be located downstream of the hydrogen sulfide and moisture removal units. Summary of Improvement Plan 59 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

73 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water 7 Improvements Phasing and Cost Analysis There are several factors that must be considered when determining when to implement the biosolids facility improvements. Some of the factors include: Age and Condition of Existing Processes Requirement to Maintain Biosolids Facilities in Operation Availability of Funding in Relation to Competing Infrastructure Needs Outside of the AWTF Analysis of Hauled Waste Alternatives Cost of Recommended Improvements This section presents costs of the various recommended improvements as well as an implementation schedule which was developed in conjunction with CRW. 7.1 Age and Condition of Existing Processes A separate condition assessment was completed in advance of this evaluation which identified significant infrastructure needs within the AWTF biosolids facilities. The implementation plan addresses these needs in order of priority as discussed with CRW, beginning with the improvements to the primary digester facilities. 7.2 Maintain Biosolids Facilities in Service Maintaining facilities in full operation in order to process biosolids is an important consideration in developing the implementation plan phasing. Projects need to be phased in order to maintain access for plant operations. 7.3 Availability of Funding in Relation to Other Infrastructure Needs In addition to the AWTF, CRW owns and operates other significant infrastructure that serves the City of Harrisburg and the surrounding municipalities. Infrastructure includes a surface water storage reservoir, water conveyance and distribution, a water treatment plant, and sewer collection system and pumping stations. The amount of available funding is limited so implementation of capital projects recommended as part of this plan need to be phased in order to limit impacts to ratepayers. Further evaluation also should be done on gas production and utilization alternatives in the context of available grant funding to offset costs of the recommended program. 7.4 Analysis of Hauled Waste Alternatives Co-digestion of hauled waste will require significant new infrastructure and additional ongoing labor and maintenance. The anaerobic digestion facility will also require additional testing and operational monitoring to reduce the impacts co-digestion could have on the anaerobic digestion facility. Identifying, scheduling, and receiving acceptable hauled waste to provide a consistent feed to the digester, will also require additional efforts. To assess the merits of expanding the hauled waste program, an evaluation was performed to consider the costs and benefits of the co-digestion of hauled waste, and the beneficial use of biogas to generate heat and electricity. The continued anaerobic digestion of the biosolids produced by the AWTF was not included in this economic evaluation. The benefits of biogas production, and biosolids stabilization and reduction are well established for municipal wastewater treatment plants of similar size. Improvements Phasing and Cost Analysis 60 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

74 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water In addition, the do nothing alternative in which the biogas utilization facilities (existing boilers and engine driven generators) are not replaced, would result in the open flaring of the biogas. The environmental impacts and public perception of open flaring makes the do nothing option undesirable, and is also not included in the cost analysis. Three alternatives were considered: Base Case Hauled Waste received at about 50-60% of the total feed to the digesters (VSS mass basis) and needed to keep digesters operating at design capacity 30% Hauled Waste Hauled Waste quantity is limited to 30% of the total feed to the digesters (VSS mass basis) No Hauled Waste Only AWTF biosolids are digested. Alternative 1 - Hauled Waste Base Case In the base case, sufficient hauled waste is received to feed the two existing primary digesters at their design capacity loading rate. To account for the unavailability of the digesters, including for maintenance and repairs, 95% of the theoretical digester capacity (VSS mass basis) is used in the cost analysis. The percentage of hauled waste to total digester feed will change as the amount of AWTF biosolids changes, but will be approximately 50-60% by volatile solids load. Operating with hauled waste at this loading rate poses a potential risk to the stable operation of the digestion process. Many factors impact the stable operation of the digestion process, but the key is consistency of the feed. A higher percentage of hauled waste can result in more variable or undesirable characteristics of feed to the digesters, as well as difficulty in maintaining consistency, and thus poses a higher risk. The quality and consistency of the hauled waste (i.e., the hauled waste s ease of digestibility) and stable operational control will be crucial to the successful operation of the digestion process. Upsets to the digestion process could result in decreased solids reduction, and therefore reduced biogas production. Excessive foaming is also commonly encountered when the digestion process is out of balance. Provisions have been included in this Improvements Plan to incorporate hauled waste pretreatment, storage, flow equalization, and blending with thickened primary and waste activated sludge, feed control and a digester mixing system to reduce the risk of these potential issues. In addition, provisions need to be in place to allow one of the digesters to be taken offline for cleaning and maintenance. Operating with high percentages of hauled waste with only one digester is not recommended. To mitigate these risks, the base case not only includes costs for the hauled waste facility and equalization tank, but also includes the installation of an acid phase digester to provide two phase digestion, and the upgrading of a secondary digester to have the capabilities of the primary digesters, including mixing and heating. Alternative 2-30% Hauled Waste In the second alternative, the hauled waste is limited to 30% of the total feed to the digesters. By limiting the percentage of hauled waste, a more stable digestion process is likely when compared with higher hauled waste percentages. The total feed to the digester will vary based on the AWTF biosolids, but in general the digesters will be operating at 60-70% of their design capacity. Operating with the digester feed at 30% hauled waste (VSS mass basis) will allow one digester to be taken off line for maintenance and cleaning, with only a moderate risk to the digestion process. Therefore, the secondary digester upgrade would not be required in this alternative. In addition, two phase digestion would not be justified. Therefore, this alternative includes costs of the hauled waste facility and equalization tank, but does not include capital costs for the acid phase digester or secondary digester upgrades. Alternative 3 - No Hauled Waste In the third alternative, no hauled waste is received and only AWTF biosolids coming in from the collection system are digested. This alternative does not include any costs for a hauled waste facility or equalization tank. Improvements Phasing and Cost Analysis 61 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

75 Hauled Waste Cost Analysis Parameters and Assumptions Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water In all three alternatives considered in the economic analysis to receive hauled waste, the following biosolids projects are not impacted by hauled waste. Primary Digester Improvements Secondary Digester Rehabilitation Gravity Thickener Refurbishment Dewatering Upgrades The total cost of the CHP and biogas handling facilities is $13,400,000, which includes infrastructure to address additional gas production anticipated with a hauled waste program. The incremental cost attributed to hauled waste is $2,700,000. Therefore, without hauled waste (Alternative No. 3), the CHP and biogas handling facilities could be reduced in capacity, with a cost reduction of $2,700,000. Thus, the incremental cost of CHP associated with Alternative Nos. 1 and 2 is $2,700,000. For all alternatives, WAS Thickening is assumed to be required regardless of the acceptance of hauled waste. The estimated cost of the combined WAS Thickening and Hauled Waste Facility is $9,700,000. If the hauled waste components were removed from this facility, the estimated facility cost could be reduced by $3,210,100. Therefore, the incremental cost associated with Alternative Nos. 1 and 2 is $3,210,100. The cost of the Acid Phase Digester, and conversions of a Secondary Digester to a Primary Digester of $9,560,000, are included as an incremental capital cost for Alternative 1. Since these facilities are not required for Alternative Nos. 2 and 3, there is no corresponding incremental cost assigned. The total incremental increase in capital costs relative to the no hauled waste alternative, are shown in Table 7-1. Table 7-1. Incremental Capital for Hauled Waste Alternatives Alternative CHP WAS Thickening / Hauled Waste Facility Acid Phase Digester and Secondary Digester Retrofit Total Incremental Capital 1 - Hauled Waste Base Case 2-30% Hauled Waste 3 - No Hauled Waste $2,700,000 $3,210,100 $9,560,000 $15,470,100 $2,700,000 $3,210,100 $0 $5,910,100 $0 $0 $0 $0 The cost analysis includes assumptions for several key factors that will vary with market conditions, including electricity and fuel costs. Also, the new facilities will require ongoing maintenance, which is included. The tipping fee to be charged by CRW for hauled waste will be based on the volume of waste delivered, and will be influenced by market conditions, transportation costs and other variables. The cost analysis uses the following assumptions: Electricity rates (based on current) of $0.05 per kwh purchased and $ per kwh sent to the grid from the generators. The recovered heat will offset the cost of purchasing another fuel, for example natural gas. Natural gas cost (based on current) of $5.30 per 1,000 cu ft. Improvements Phasing and Cost Analysis 62 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

76 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Only the recovered heat that can be used for heating the digesters (year round) and heating the building space (during winter months only), is included in each alternative. Maintenance and operating costs of 2.2% of the total project cost annually, beginning the year following the time of capital expenditures. Tipping fee received for hauled waste of $40 per 1,000 gallons. To provide a straightforward analysis of the costs and benefits of receiving hauled waste, a simple rate of return, the payback period was calculated. This type of analysis ignores the time value of money, and the potential growth of AWTF biosolids. Although these parameters are significant in this case, the simple rate of return and payback period remains meaningful and provide an easily interpreted analysis. The simple rate of return is calculated by dividing the annual benefit by the incremental capital and converting to a percentage. The simple rate of return could be compared to other investment opportunities, or to the cost of funding the project. The payback period represents the number of years the project would have to be operated at the assumed conditions, to provide a benefit equal to the incremental capital. The simple rate of return and the years to payback for the three hauled waste alternatives are included in Table 7-2. The financial analysis in Table 7-2 are based on the single point of capital costs, and input values described above. A sensitivity analysis of some of the variables that could affect the economics of the Alternatives are discussed below. Table 7-2. Hauled Waste Alternatives Cost Analysis Alternative Incremental Capital Annual Benefit 1 Simple Rate of Return Payback Period 1 - Hauled Waste Base Case 2-30% Hauled Waste 3 - No Hauled Waste $15,470,100 $892, % 17 $5,910,100 $529, % 11 $0 $276,964 N/A N/A 1. Annual Benefit = First Year Revenue from Electric Generated + Offset of Natural Gas that would otherwise be required for Heating + Tipping Fee Revenue Hauled Waste Disposal Maintenance Costs of the Incremental Capital Facilities Since the incremental capital in Alternative 3 is zero (0), the simple rate of return and payback period cannot be determined. However, the annual benefit for the three alternatives can be directly compared. The annual benefit for Alternative 2 is nearly twice that of Alternative 3, and the annual benefit of Alternative 1 is more than three times more than that of Alternative 3. For Alternative 2, the rate of return on the incremental capital needed for this alternative is 9.0% and will pay back the capital investment in eleven (11) years. To operate reliably with Alternative 1, the rate of return on the incremental capital is only 5.8%, and it will take 17 years to pay back. The lower rate of return is due to the greater increase in capital than increase in annual benefit when compared to Alternative 2. Net Present Value The Net Present Value (NPV) was also calculated to provide a time dependent analysis of the costs and benefits of the three hauled waste alternatives. The cost of disposal of hauled waste was included in the NPV calculation. A 60% destruction of volatile solids in the hauled waste and a 22% dewatered cake was assumed in calculating the wet tons of hauled waste associated solids. Improvements Phasing and Cost Analysis 63 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

77 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water The net present value included the incremental capital and maintenance costs, the benefits of the electricity generated, and heat recovered, and the time value of money (3% discount rate, assumed). The NPV is calculated over a 25-year period starting in The NPV spreadsheets are included in Appendix B, and a summary is provided in Table 7-3. Table 7-3. NPV for Hauled Waste Alternatives Alternative NPV 1 - Hauled Waste Base Case $1,100, % Hauled Waste $6,000, No Hauled Waste $5,500,000 The NPV values for Alternatives 2 and 3 are essentially the same given the relatively long period being considered, and the numerous assumptions. Alternative 2 results in the highest net present value. Alternative 2 is conservative in the assumptions used for the NPV, providing opportunity for the hauled waste program to perform better than expected, which could potentially increase the NPV. Tax credits and grants may also be available for the hauled waste Alternatives 1 and 2 that may enhance the economic viability of those options. Risks to the Hauled Waste Alternatives The simple economic analysis and NPV calculation provide a comparison of three hauled waste alternatives. Understanding the risks involved with the three alternatives provides further justification to selecting an alternative. Risks to accepting hauled waste include: The analysis assumes hauled waste that is amenable to co-digestion with municipal biosolids Identifying and receiving the actual quantity of hauled waste compared to the projected quantity in the analysis Obtaining the projected tipping fee ($40/1000 gallons) on average for the highest quality hauled waste The growth of the biosolids from the AWTF service area growth may or may not occur Monitoring of incoming hauled waste and close attention to the operation of the digesters are critical to consistent digestion and gas production. Both tipping fee and the costs of maintenance can have a significant impact on the NPV. Selecting equipment with low maintenance requirements and maximizing tipping fees within the available source market can both result in a positive NPV result. Sensitivity Analysis A limited sensitivity analysis was also conducted on the hauled waste cost analysis. Included in the sensitivity analysis were the following variations: Increase capital costs by 20% Decrease capital costs by 15% Increase electricity costs by 50% Decrease electricity costs by 20% Increase natural gas costs by 50% Improvements Phasing and Cost Analysis 64 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

78 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Increase Hauling Cost by 15% The spreadsheets for each of the NPV scenarios, taken individually and not collectively, are included in Appendix B. The range of NPV, Simple Rate of Return and Payback Period from the sensitivity analysis were also evaluated. For Alternative 1, the NPV ranges from ($900,000) to $6,300,000. The negative NPV indicating the project benefits would not break even with the project costs after 25 years. The simple rate of return range from 4 to 8%, and the years to payback range from 13 to 23 years. The simple rate of return and payback do not incorporate the time value of money resulting in more optimistic results. For Alternative 2, the NPV ranges from $4,500,000 to $9,900,000. By limiting the hauled waste received to a conservative 30% of the volatile solids fed to the digesters, the capital costs are reduced, and for the variations studied, the project results in a net benefit to CRW. The simple rate of return range from 7 to 12%, and the years to payback range from 8 to 14 years. Other Biosolids Improvement Plan Benefits There are other benefits that should be considered in evaluating the justification for the biogas utilization projects. Providing emergency back-up power, for critical treatment operations, to the AWTF is one benefit. Currently the AWTF is supplied power from two different sources, but in the event of a catastrophic weather event, both sources could be lost. Providing back-up power from the CHP system would not be affected by most weather events. Biogas is a renewable resource and utilizing it to generate electricity and heat offsets the use of non-renewable resources such as petroleum and coal. Another benefit not included in the cost analysis calculation, is the possibility that that portions of the capital costs may qualify for green energy tax credits, grants, and low interest funding. Hauled Waste Recommendation Accepting hauled waste will require new infrastructure and operational and maintenance support. Accepting hauled waste also introduces risks to the digestion process, and identifying, negotiating, and receiving high quality hauled waste will also add complexity to the overall AWTF operation. At the same time, the potential opportunity to provide a long-term positive net economic impact to the AWTF as well as providing environmental and public relations benefits merits further evaluation of the hauled waste program. Alternative 2, or limiting hauled waste to 30% of the digester feed, was found to have a shorter payback period compared to Alternative 1, the base case. This alternative merits further consideration since it offers the potential for the plant to incrementally increase the volume of hauled waste received while the plant monitors and evaluates the stability of the digestion process. 7.5 Summary and Cost of Improvements A summary of capital improvements is presented in Table 7-4. Estimated costs of each of the capital improvements are shown in Table 7-5. Improvements Phasing and Cost Analysis 65 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

79 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 7-4 Summary of Improvements Process Summary Description Key Design Criteria Primary Digesters (Upgraded) Two (2) existing primary digesters on line Replace gas mixing system with mechanical mixing system Replace primary digester fixed covers Replace gas and sludge piping internal to the digesters Replace sludge piping and valves within the digester control house gallery Replace waste gas flare Replace primary digester recirculation pumps Replacement of primary digester transfer pumps New electrical and controls building At Digester Capacity: Solids Loading Rate: 76,900 lbs TSS/day 61,000 lbs VS/day 0.18 MGD 5% Solids Loading Rate: 0.12 lbs VS/cu ft/d SRT: 20 days Enginator Refurbishment Refurbish Enginator Equipment Two (2) 400 kw Units Clean Tank Volumes: 924,000 and 839,000 gallons Secondary Digesters Refurbishment Replace Roofs Diameter: 85 ft Replace Sludge Mechanisms (2) Side Water Depth: 28 ft 80 Foot Diameter with scum collection Gravity Thickeners (Upgraded) Replace Thickened Sludge Pumps (3) 210 gpm with VFD Replace Scum Pumps (2) 50 gpm Improvements Phasing and Cost Analysis 66 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

80 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 7-4 Summary of Improvements Process Summary Description Key Design Criteria Combined Heat and Power Facility (Existing Building, New Equipment) Reciprocating Engine Driven Generator Units (3) Replace low pressure gas compressors (2) Generator Output, each: 500 kw Electricity Generated, 480 V 3 phase 60 Hz 4 wire Size: 4 x 4 inches Output Pressure: psia Capacity, each: 240 cfm Gas Collection, Storage and Pretreatment (Upgraded) Replace Hydrogen Sulfide Removal and Particulate/Condensate Units Treatment volume: 40 cf Capacity: 45,000 scf/day Pressure drop: 0.5 in of water column Boiler Building (Existing Building, New Equipment) Existing One (1) Storage Tank New Steam Boiler (1), Back up to CHP Size: 42 ft diameter Pressure, max: 50 psig Capacity: 38,793 ft 6,000,000 Btu/hr Improvements Phasing and Cost Analysis 67 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

81 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 7-4 Summary of Improvements Process Summary Description Key Design Criteria Volumetric Loading Rate: 300 gpm per meter of belt width Gravity Belt Thickeners (3) Solids Loading Rate: 500 lbs TSS per hour per meter of belt width Feed % Solids: % TSS TWAS % Solids: 4-6% TSS WAS Thickening (New) Thickened Sludge transfer pumps(2) Number of Operating Hours a Day: 33 hrs per day 16.5 hrs/day with two GBT units operating Sludge Blending Tank New building for GBT and hauled waste receiving facilities gpm 50 ft head VFD driven motor 100,000 gallon Capacity Two Story 45 feet by 75 feet Acid Phase Digester 1.5 days SRT Secondary Digester Retrofit to Primary Digester & Acid Phase Digestion (New) Convert one secondary digester to functioning anaerobic digester with upgrades similar to primary digester scope listed above. Retrofit one secondary digester 300,000 gallons volume Improvements Phasing and Cost Analysis 68 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

82 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 7-4 Summary of Improvements Process Summary Description Key Design Criteria with linear motion mixer and replacement roof One hauled waste receiving station with automated access station including 600 gpm unloading rate - Rock Trap - Screen - Grit Removal - Grease Removal - FOG Bypass Hauled Waste Receiving (New) Holding Tank 75,000 gallons Capacity Hauled Waste Transfer Pumps (2) gpm 50 ft head VFD driven motor Volumetric Loading Rate: gpm, each Dewatering Facilities (Upgraded) Two (2) new centrifuges gpm total Solids Loading Rate: 2,000 lbs dry solids/hr, each, 4,000 lbs dry solids/hr total Sludge Storage Facilities (Existing) Maintain Structure Recoat Structure as needed Replace Roofing as needed Improvements Phasing and Cost Analysis 69 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

83 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Table 7-4 Summary of Improvements Process Summary Description Key Design Criteria Additional Storage Shed 52 feet by 50 feet, with 6 ft sludge height Relocation of Tipping Scale 19 day sludge capacity A rough order of magnitude (ROM) project cost estimate for each phase is shown in Table 9-5. The information is based on data gathered in The ENR Construction Cost Index on August 2017 was Table 7-5. Project Cost Estimates Included Projects Low Estimate -20% Contingency High Estimate +50% Contingency Point Estimate 0% Contingency Primary Digester Improvements CHP Evaluation & Enginator Rehabilitation Hauled Waste and Gas & Power Generation Market Evaluation Secondary Digester Rehabilitation $9,500,000 $13,400,000 $11,100,000 (1) $600,000 $1,125,000 $750,000 $160,000 $300,000 $200,000 $2,900,000 $5,400,000 $3,600,000 Gravity Thickeners $1,500,000 $2,800,000 $1,900,000 CHP and Gas System Upgrades WAS Thickening and Hauled Waste Secondary Digester Retrofit to Primary Digester & Acid Phase Digestion $10,700,000 $20,100,000 $13,400,000 $7,800,000 $14,600,000 $9,700,000 $7,650,000 $14,340,000 $9,560,000 Dewatering $6,100,000 $11,500,000 $7,600, Primary Digester Improvement Point, Low, and High Estimates based on July % Basis of Design Estimate Improvements Phasing and Cost Analysis 70 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

84 7.6 Biosolids Facilities Improvements Phasing Plan Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water A phased implementation plan, presented in Figure 7-1, was developed following the preparation of the biosolids facilities improvement projects and in consultation with CRW. The phased approach is intended to address immediate priorities while balancing recommended future improvements with CRW s other system-wide infrastructure needs. The immediate priority for the AWTF Biosolids Facilities is the rehabilitation of the primary anaerobic digesters and related equipment, such that the plant can fully utilize existing equipment and maintain a stable and reliable digestion process. The Primary Digester Improvements, identified as Phase 1, will provide greater reliability for digestion with improvements in mixing, recirculation and heating, and will be starting construction in Phase 2 will include the refurbishment of the enginators to provide more reliable service in the short term and will also include an investigation of alternative biogas utilization options. Phase 3 will include an expanded market analysis of hauled waste generators, and will develop recommendations for a fee structure for the implementation of a hauled waste program. Phase 4 addresses the reliability of the gravity thickeners and the secondary digesters with a planned refurbishment of each facility. Phases 5 and 6 include major infrastructure improvements to biosolids handling and resource (energy) recovery systems, and allow for an expanded hauled waste receiving program at the AWTF. It is anticipated that the Phase 5 and 6 projects will be further refined through evaluations performed in Phases 2 and 3. Figure 7-1. Phasing Implementation Improvements Phasing and Cost Analysis 71 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

85 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Appendices Appendix A Technical Memoranda TM-1 Proposed Biosolids Plan Appendices 72 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

86 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 1 SUBJECT: Prepared by: Reviewed by: Biosolids Master Plan Overview D. Nixson, N. Cohen M. Olivier, J. Emerson Distribution: Date: June 9, 2017 Revised on: August 11, 2017 CONTENTS I. INTRODUCTION II. DESIGN CRITERIA ATTACHMENTS: 1.) Not applicable. REFERENCE DRAWINGS: 2.) Not applicable. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

87 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 I. INTRODUCTION The Harrisburg Advanced Wastewater Treatment Facility (AWTF) is owned and operated by Capital Region Water (CRW) and was originally constructed in 1959, and currently is permitted to treat an average of 37.7 million gallons per day (MGD) of wastewater collected from the City of Harrisburg and outlying areas. The liquid-side biological treatment process was recently upgraded, to meet more stringent nitrogen and phosphorous limits. A team led by Whitman, Requardt & Associates, LLP (WRA) has been retained to evaluate the biosolids facilities at the AWTF and develop a plan that allows CRW to meet their goals and objectives for these facilities. This technical memorandum briefly reviews the work completed to date and provides an outline to establish the long term planning for the AWTF biosolids facilities. WRA completed a condition assessment of the biosolids facilities in February Biosolids facilities include: Two (2) Gravity Thickeners Two (2) Fixed Cover Primary Anaerobic Digesters Two (2) Secondary Anaerobic Digesters, one with fixed cover and one with floating cover Two (2) 2.5 Meter Belt Filter Presses Covered Biosolids Storage One (1) Gas Storage Tank Two (2) Biogas Driven 400 kw Internal Combustion Engine Driven Generators Three (3) Concentric Tube Heat Exchangers Two (2) Biogas Fueled Hot Water Boilers Polymer feed systems, pumps, piping and conveyance systems to support the operations. Sludge from the primary sedimentation tanks is mixed with waste activated sludge (WAS) prior to the solids handling processes. The combined sludges are thickened in gravity thickeners, anaerobically digested in primary digesters, stored in secondary digesters and dewatered using the belt filter presses. The dewatered sludge is stored onsite temporarily before being hauled away by a contractor and land applied to local farms. Biogas is stored and used for building heat and to provide fuel to generate electricity to sell back to the power company to offset plant power costs. In general, the Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Existing Conditions Report (February 2017) found the biosolids related tanks and buildings to be in fair to good physical condition. The mechanical systems on the other hand are in poor condition and are operating well beyond their expected life. Exception to this were the dewatering belt filter presses which were installed in 2007, and are fully operational. CRW is progressive with their goals and objectives for the biosolids facilities. They have long recognized there is real value in the biosolids which are generated by the AWTF, both through beneficial reuse of the biosolids, and also through utilization of the biogas that is generated during August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

88 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 anaerobic digestion. Due to improvements in technology and advancements in operational philosophies, e.g. focus on energy efficiency and resource recovery, since the AWTF biosolids facilities were installed, there are opportunities to expand on the resources recovered from the biosolids. CRW current goals for biosolids include: Increase the energy recovery from biosolids, Develop facilities that provide operational and energy efficiency, Improve long term sustainability. WRA has evaluated the biosolids treatment process and has determined there are beneficial changes that can be made to the biosolids facilities to allow CRW to better attain their goals. Recommendations include the following major modifications: Separately Thicken Waste Activated Sludge and Primary Sludge This process modification has been proven at many facilities to greatly increase the percent solids in the thickened sludge sent to the anaerobic digesters. The co-thickened sludge at AWTF is currently averaging approximately 3% solids. Separate thickening is expected to result in 4-6% solids in each sludge stream. This in turn will increase the solids retention time in the anaerobic digesters, which increases volatile solids reduction and biogas generation, and reduces the quantity of digester gas required to heat the sludge. Increase Utilization of the Existing Anaerobic Digesters CRW currently only needs to operate one of their two primary digesters. With the decrease in volume from separate sludge thickening, there will be additional capacity in the digesters. This additional capacity can be put to beneficial use for CRW by accepting hauled waste, e.g. food processing waste. In 2017, CRW began experimenting with feeding hauled waste into their anaerobic digesters. Based on the current and projected capacity of the anaerobic digesters, there is an opportunity to formalize and expand the receipt of hauled waste, with the goal of generating additional biogas and revenue. Combined Heat and Power Station With the improved digester efficiency, along with the increase in hauled waste and the resulting increase in biogas, there is an opportunity to better optimize heat and electrical power recovered from the biogas generated. A combined heat and power station would provide an opportunity to improve the overall energy recovery efficiency. Anaerobic Digestion Improvements The anaerobic digesters are planned to be refurbished with new mixing, and pumping equipment and the replacement of the fixed covers. In addition to these improvements, the mineral build up in the heat exchangers was evaluated, along with the addition of an acid phase digester. Hauled waste can have an adverse effect on the digesters due to large variations in volume and August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

89 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 characteristics. Equalization tanks can help provide for a more consistent feed to the digesters and will be included with the hauled waste receiving system. As a further improvement in anaerobic digester performance and gas production, the addition of an acid phase digester should be considered. One of the widely reported benefits of acid phase digestion is the reduction in foaming events, like those caused by inconsistent feed to the digesters. Outline of Biosolids Facilities Technical Memorandum Separate Technical Memoranda will be developed to provide further details of the plans for the major biosolids facilities. The following is a list of anticipated Technical Memoranda and their subject matter. Once the Technical Memoranda are completed and reviewed with CRW, a report summarizing the facilities plan will be developed and the Technical Memoranda will be included as appendices. Table 1-1 indicates of anticipated technical memoranda. Technical Memorandum Number Table 1-1. Technical Memorandum Facilities/Processes 1 Proposed Biosolids Facilities Plan 2 Waste Activated Sludge Thickening 3 Hauled Waste Receiving 4 Anaerobic Digesters Ongoing Upgrades Acid Phase Digestion Mineral Deposits and Heat Exchangers 5 Hauled Waste Projections 6 Dewatering Facility 7 Biogas Utilization Biogas Projections Biogas Pretreatment Utilizing Biogas for Heat and Power Generation II. DESIGN CRITERIA Biosolids Generated A review of the 2013 to 2016 AWTF influent flows, biological oxygen demand (BOD5), and TSS conducted in the Biosolids Facilities Improvement Existing Conditions Report concluded the loadings to the plant vary within a consistent range. CRW anticipates only a modest number of August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

90 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 new connections will be made to the collection system. Therefore, future primary and waste activated sludge quantities can be expected to generally remain within the current ranges, experienced following the recent nutrient removal upgrades. The WAS volumes have increased substantially since the nutrient removal process modification, which included wasting mixed liquor rather than settled sludge. The WAS volumes and loads are currently exceeding the recent biological nutrient removal (BNR) upgrade expected values. The practice of wasting mixed liquor is expected to continue for the foreseeable future. As such, Table 1-2 contains the WAS and primary sludge volumes and quantities that will be utilized in the remainder of the Biosolids Facilities Improvement Plan. Table 1-2. Sludge Design Criteria Average, Current 1 Projected Design Values 2 Influent Flow 19.5 MGD 37.7 MGD Primary Sludge WAS 25,600 5,800 mg/l 0.44 MGD 16,600 2,700 mg/l 0.72 MGD 27,750 5,800 mg/l 0.60 MGD 25,000 lbs/day 2,500 mg/l MGD 1 Data from May 2016 to June 2017 (after BNR upgrade online) 2 AWTF BNR Upgrade Design Maximum Month 3 Calculated using a peaking factor of 1.3 times the current annual average WAS mass rates 4 Based on continued wasting from mixed liquor channel, concentrations may range from 2,000 to 3,000 mg- TSS/L Thickened Solids With the separate thickening of WAS, the existing gravity thickeners are expected to thicken the primary sludge to 4-6% solids. The gravity belt thickeners for the WAS thickening would have the preliminary design criteria shown in Table 1-3. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

91 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 Table 1-3. Gravity Belt Thickeners Units 3, in parallel Type Loading Rate, Volumetric Loading Rate, Solids Feed Percent Solids Horizontal Gravity Belt 300 gpm per meter of belt width 500 lbs TSS per hour per meter of belt width 0.2 % TSS The thickened WAS would flow by gravity to a blending tank to provide flow equalization prior to being pumped into the primary anaerobic digesters. The flow equalization tank will be sized to hold 24 hours of thickened WAS. The tank would be aerated with coarse bubble diffuser to also provide agitation. Hauled Waste A hauled waste receiving station would include the major components in Table 1-4. Table 1-4. Hauled Waste Receiving System Capacity 700 gpm max flowrate Screening Grit and Grease Removal Holding Tank 10 mm openings perforated plate with Washer/Compactor Inclined grit removal screw with integrated grease skimmer Square Concrete with capacity of 1 day at max day receiving rate August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

92 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 Table 1-4. Hauled Waste Receiving System Accessories Rock Trap Flow Meter Screenings and grit dumpster Hauler Access Station - Scan Card Reader and Billing System Anaerobic Digesters The primary and secondary digesters would operate as they are currently configured, with the secondary digesters mainly performing as holding tanks. Design criteria for the primary digesters are shown in Table 1-5. Table 1-5. Primary Digesters Units 2, in parallel Working Capacity Design Feed Rate Design Solids Retention Time Volatile Solids Destruction 1,833,000 gallons, each 3,667,000 gallons, total 2.2 kg-vss/m 3 /d 0.14 lbs-vss/ft 3 /d 15 days, minimum 20 days, design with both on line 50%, design Currently the AWTF encounters mineral buildup in the digester heat exchangers and piping. From a laboratory test of the mineral, along with circumstantial evidence, the mineral appears to be hydrated iron phosphate, or as the mineral is known, vivianite. There is the potential to address the mineral build up in the heat exchanger with alternate heat exchanger technologies such as the spiral heat exchanger, and the scraped surface heat exchanger. The capital costs of this equipment compared to the cost of replacing piping and valves, and heat exchanger tubes, is not likely to be a cost effective strategy. The existing concentric tube sludge heat exchangers would remain in service. Alternatively, the AWTF could evaluate the use of aluminum salts rather than ferric chloride, but the aluminum salts tend to be more expensive. Regardless, the increased chemical costs may be August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

93 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 offset by increased operational and maintenance efficiencies. The recommendation for addressing vivianite build up is with direct steam injection. In Phase 1 Primary Digester Improvements, steam lances will be built into the primary digesters. Steam lances will eliminate vivianite build up in the heating loop along with eliminate the use of external heat exchangers. Acid Phase Digestion The stabilization (digestion) of biosolids occurs in three steps, hydrolysis, acidogenesis (acid formation), and methanogenesis (methane generation). Acid formation and methane generation are performed by different bacteria, which prefer different conditions. Currently all three steps occur in the primary digesters, and therefore there is a compromise of environmental conditions. To provide conditions that favor the acid forming bacteria, a digester can be installed upstream and in series with the primary digesters. The acid phase digester is designed with a short solids retention time (SRT) compared to the primary digester. Acid phase digestion has the following reported benefits: Greater consistency in feed rate and temperature to the primary digesters Increased biogas generation in the primary digesters Reduced digester upsets (fewer occurrences of foaming) A cost effective way to incorporate acid phase digestion at the AWTF would be through the addition of a single digester tank. The feeds from the gravity thickener underflow, thickened WAS holding tank, and hauled waste equalization tank would be blended and pumped into the acid phase digester. The key design parameters of the acid phase digester are in Table 1-6. Table 1-6. Acid Phase Digester Units 1 Working Capacity Design Feed Rate Design Solids Retention Time Operating Temperature 300,000 gallons 0.15 MGD 2 days, minimum Mesophilic, 96-99º F August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

94 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 The potential in increased biogas production through the addition of an acid phase digester will not economically justify the digester. As the AWTF receives more hauled waste, especially hauled waste from a variety of sources, the operational benefits of an acid phase digester will become more important. Therefore provisions for acid phase digester, including maintaining open space, should be incorporated into currently planned projects. The value of the acid phase digester would be re-evaluated periodically to determine when it should be constructed. Dewatering Facility Considering that the existing belt filter presses are in good working condition, and generally produce cake solids with sufficiently high solids, they would continue to be utilized. A separate study on improving the dewatered cake solids is anticipated to supplement this report. Table 1-7 provides some of the key design parameters of the existing belt filter presses. Table 1-7. Belt Filter Press, Existing Units 2 Type Dual belt with separate gravity and compression sections Belt Width 2.5 meters Design Feed Rate Typical Dewatered Cake Solids 2,000 lbs dry solids/hour % solids The belt filter presses would need to operate more hours a day to accommodate increased solids production that would result from hauled waste. The existing belt filter presses are insufficient to dewater the solids when the digesters are operating at design conditions. Prior to reaching their capacity, a third belt filter press would need to be installed. Biogas Utilization The ongoing upgrades to the primary digesters, along with the increased solids retention time, and increased acceptance of hauled waste, the volume of biogas generated is expected to increase, potentially by more than 250% over current average volumes. To make the most use of this asset, a combined heat and power plant is proposed. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

95 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 1 The AWTF currently separately generates heat in two (2) boilers and electricity in two (2) reciprocating engine driven generators. They also recover some of the waste heat from the reciprocating engine. Combining heat recovery and electricity generation in one package unit increases the total energy recovered from the biogas. The United States Department of Energy reports a nationwide average energy recovery from separate heat and power of 50%. For combined heat and power (CHP) systems, the overall energy efficiency is typically around 75% 1. More than 50% of CHP installations are reciprocating engine driven. Reciprocating engines are a mature technology with well-established and wide spread parts availability and service representatives. AWTF personnel are also familiar with operating and maintaining the reciprocating engine driven system. The fuel cell CHP system is another technology which is being reviewed. Fuel cells produce electricity by separating the hydrogen from the methane, and then combining it with oxygen from the atmosphere to produce electricity. The process produces waste heat which is recovered. The fuel cells have no emissions, high overall energy efficiency, and good performance at partial loadings. Fuel cells have a higher capital cost than reciprocating engines, and do wear out over time and need replacement. In addition, the biogas requires additional pre-treatment to provide the high quality fuel required. For either the reciprocating engine or the fuel cell, biogas pre-treatment would be installed. 1 August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM01 - Biosolids Overview.docx

96 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water TM-2 Sludge Thickening Appendices 73 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

97 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 2 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 2 SUBJECT: Prepared by: Reviewed by: Sludge Thickening D. Nixson M. Olivier, J. Emerson Distribution: Date: June 9, 2017 Revised on: August 11, 2017 CONTENTS I. INTRODUCTION II. DESIGN CRITERIA ATTACHMENTS: 1.) Alfa Laval Ashbrook Budgetary Proposal Dated May 18, ) General Arrangement Drawing of Ashbrook Simon-Hartley 2.0 Meter Aquabelt Enclosed REFERENCE DRAWINGS: 1.) Not applicable. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM02 - Sludge Thickening.docx

98 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 2 I. INTRODUCTION See Technical Memorandum No. 1 for a description of the Harrisburg AWTF and the overall biosolids process. Technical Memorandum No. 2 provides summary design information regarding the thickening of sludge at the AWTF. The AWTF currently combines primary sludge collected from the primary clarifiers, waste activated sludge (WAS) from the mixed liquor channel, and diluting water and co-thickens the blended sludge in two (2) gravity thickeners. The thickener underflow averages 3% suspended solids, which is pumped to the primary digesters. At current flows and loads, the primary digester has a solids retention time (SRT) of 14.4 days in the one primary digester. This calculation assumes the digester is free of debris and the full volume of the tank is usable. By increasing the solids content of the sludge to a minimum of 5% solids, the volume of sludge would be reduced from 159,500 gallons per day to 95,700 gallons per day. This would increase the SRT to 19 days, potentially increasing volatile solids reduction and biogas production. Alternatively, and to greater benefit to CRW, more hauled waste can be loaded into the digesters resulting in additional gas production. Although there are several proven technologies for thickening WAS, the gravity belt thickener (GBT) and the centrifuge are best suited to thickening the low solids content (0.2 % solids) of the AWTF WAS to reliably above 5% solids. Another technology that should be considered is the volute thickener, a relatively new technology. The volute thickener would have several advantages over the gravity belt thickener and centrifuge including: Small footprint (comparable to centrifuge) Low energy demand Simple maintenance requirements Low capital costs There are relatively few installations of volute thickeners in the United States, and it is unknown if any of these installations are thickening WAS as low in solids (0.2% TSS) as the AWTF. Therefore a pilot test would be recommended prior to proceeding with this option. The GBT has several advantages over the centrifuge including: Low capital cost Low energy consumption Simple operation and maintenance Ability to handle stringy solids (i.e. rags) and plastics In addition, the AWTF operations is familiar with the operation of a GBT, as the equipment is very similar to a belt filter press. One of the disadvantages of the GBT is the physical size is larger than August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM02 - Sludge Thickening.docx

99 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 2 a similar capacity centrifuge. The use of a centrifuge will reduce the overall size of the thickening building, which would offset some of the higher capital costs of the centrifuge. A proposed thickening building would house the GBT facilities including the wash water booster pumps, the polymer handling system, and thickened WAS (TWAS) transfer pumps. The TWAS would be stored in a holding tank to allow consistent flow to the digesters when blended with the gravity thickened primary sludge. The existing gravity thickeners would continue to thicken primary sludge, but only one thickener would need to be online at a time. II. DESIGN CRITERIA The design quantities and solids content for primary and waste activated sludge are in Table 2-1. Table 2-1. Sludge Design Criteria Average, Current 1 Projected Design Values 2 Influent Flow 19.5 MGD 37.7 MGD Primary Sludge WAS 25,600 5,800 mg/l 0.44 MGD 16,600 2,700 mg/l 27,750 5,800 mg/l 0.60 MGD 25,000 lbs/day 2,500 mg/l MGD 1.2 MGD 1 Data from May 2016 to June 2017 (after BNR upgrade online) 2 AWTF BNR Upgrade Design Maximum Month 3 Calculated using a peaking factor of 1.3 times the current annual average WAS mass rates 4 Based on continued wasting from mixed liquor channel, concentrations may range from 2,000 to 3,000 mg-tss/l August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM02 - Sludge Thickening.docx

100 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 2 Key design information for the existing gravity thickeners are in Table 2-2. Table 2-2. Thickening Tanks Tanks No. of Units Dimensions, each Diameter Side Water Depth Freeboard 2, in parallel 80 feet 10 feet 1.5 feet Total Volume Total Surface Area Total Weir Length 968,775 gallons 10,053 sq ft 503 feet Table 2-3 provides typical design criteria for gravity thickeners. Table 2-3. Typical Design Criteria for Gravity Thickeners 1 Type of Solids Influent Solids Conc. % solids Expected Underflow Concentration % solids Mass Loading Rate lb/sq ft/hr (kg/m 2 /hr) Max. Overflow Rate gal/sq ft/d (m 3 /m 2 /d) Primary Primary and WAS and Iron 1 WEF Manual of Practice No (4-6) 0.31 (1.5) ( ) N/A As can be seen in Table 2-3, gravity thickeners thickening only primary sludge can be loaded at higher mass rates than with combined primary and waste activated sludge. In addition, the primary sludge, and the thickened primary sludge is expected to be at a higher percent solids. Therefore separating the primary sludge and waste activated sludge would allow for a higher percent solids being fed into the digesters. The overflow rate of the thickener was evaluated to determine if the rate when thickening only primary sludge is too low. The primary sludge flowrate has averaged 0.44 MGD over the period studied. Thickening this stream separately with a 4:1 dilution water to sludge ratio would result in an overflow rate of 220 gal/sq ft/d, which is low and subject to floating sludge, odors and septicity. Operating one thickener would be recommended to keep the dilution water quantity reasonable, and result in an overflow rate of 440 gal/sq ft/d. Also, chlorine can be added to reduce odors and maintain fresher sludge with less septicity and reduce potential for gasification. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM02 - Sludge Thickening.docx

101 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 2 With the separate thickening of WAS, the existing gravity thickeners are expected to thicken the primary sludge to 4-6% solids. Gravity Belt Thickening The gravity belt thickeners for the WAS thickening would have the preliminary design criteria in Table 2-4. Table 2-4. Gravity Belt Thickeners Quantity 3, in parallel, 2 duty, 1 standby Size 2 meter belt Type Horizontal Gravity Belt Loading Rate, volumetric Loading Rate, Solids Feed Percent Solids Number of Operating Hours a Day 300 gpm per meter of belt width 500 lbs TSS per hour per meter of belt width 0.2 % TSS 33 hrs per day hrs/day with two GBT units in operation Blending a portion of the thickened primary sludge with the WAS would improve the solids capture of the gravity belt thickener. Provisions in the piping should be considered to allow for this flexibility. The thickened WAS would flow by gravity to a blending tank to provide flow equalization prior to being pumped into the primary anaerobic digesters. The flow blending tank will have a working volume equal to 48 hours of thickened WAS, or 100,000 gallons. The tank would be agitated with coarse bubble diffusers. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM02 - Sludge Thickening.docx

102 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 2 TWAS pumps will pump from the TWAS holding tank to either of the primary anaerobic digesters, normally through the heat exchanger recirculation loop, so the TWAS could be heated prior to entering the digester. The TWAS pumps will have the design criteria in Table 2-5. Table 2-5. TWAS Transfer Pumps Quantity 2, in parallel, 1 duty 1 standby Capacity ft Head Type Hose Pump with VFD Driven Motor August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM02 - Sludge Thickening.docx

103 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water TM-3 Hauled Waste Receiving Appendices 74 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

104 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 3 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 3 SUBJECT: Prepared by: Reviewed by: Hauled Waste Receiving and Holding Tank D. Nixson M. Olivier, J. Emerson Distribution: Date: June 9, 2017 Revised on: August 11, 2017 CONTENTS I. INTRODUCTION II. DESIGN CRITERIA ATTACHMENTS: 1.) PortALogic DS-200 Waste Dump Station REFERENCE DRAWINGS: 1.) Huber Technology Rotamat Wash Drum RoFAS Conceptual Layout Drawing August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM03 - Hauled Waste Receiving.docx

105 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 3 I. INTRODUCTION See Technical Memorandum No. 1 for a description of the Harrisburg AWTF and the overall biosolids process. Technical Memorandum No. 3 provides summary design information regarding the proposed hauled waste receiving system at the AWTF. Hauled waste will be delivered in tanker trucks varying in size. Handling the waste will require unloading, pretreatment, flow equalization, blending with thickened primary and waste activated sludges, and pumping to the digesters. Equalization of these wastes reduces the potential for foaming and upset conditions as there may be considerable variability in waste volumes and characteristics. The hauled waste system would include the following components, at a minimum. Truck unloading station with containment Automated billing ticket generation Rock trap One (1) screening washing unit with bypass for grease One (1) grit trap with grease removal system Automatic sampler One (1) transfer pump One (1) equalization tank, totaling a working volume of one (1) times the daily expected volume Tank aeration/mixing system with odor control Two (2) transfer pumps to convey pretreated waste to the primary digesters The mechanical equipment for handling hauled waste would be housed in the same building as the proposed WAS thickening process. Additional pretreatment equipment may be necessary depending on the characteristics of the potential hauled waste. II. DESIGN CRITERIA The daily design quantities and characteristics of the hauled waste are being concurrently developed. The daily quantities do not affect the size of the receiving station as it is sized for the unloading rate of a single truck. The hauled waste truck would park so the outlet of the truck is within a concrete containment area which would be sloped to a plant drain. The hauled waste truck unloading station would be equipped with an automated dump station control panel. The panel would read the driver s access card, then open an automated valve, and record the totalized flow from a flow meter. This information would be stored in the panel and can be communicated across a network or downloaded for billing purposes. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM03 - Hauled Waste Receiving.docx

106 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 3 The truck would connect to an unloading station with a hose. The hauled waste will be pretreated during the truck unloading operation for the removal of inorganics (grit and screenings). Hauled waste may also include fats, oils and grease (referred to as FOG) which would bypass the screening operation. Screenings will be washed, compacted and conveyed into a dumpster. The grit that is removed will also be conveyed into the same dumpster. Table 3-1 shows key design criteria for the hauled waste receiving station. Table 3-1. Hauled Waste Receiving Station Quantity 1 Hydraulic Capacity Drum Screen Diameter Screen Openings Screenings Capacity Screenings Compacted Water Content Location Rating 1.37 MGD 47 inches 1/4 to 3/8 inch 53 cubic feet per hour 65%, maximum Class 1 Div 2 Hauled waste would be pumped into to a holding tank to provide flow equalization prior to being blended with primary sludge and WAS and pumped into the primary anaerobic digesters. The flow equalization tank will have a working volume equal to one day of expected hauled waste volume. The expected daily hauled waste volume is concurrently being developed. The tank would be agitated with coarse bubble diffusers and equipped with an odor control system. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM03 - Hauled Waste Receiving.docx

107 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 3 Hauled waste transfer pumps will pump from the hauled waste holding tank to either of the primary anaerobic digesters, normally through the heat exchanger recirculation loop, so the hauled waste could be heated prior to entering the digester. The Hauled Waste Transfer pumps will have the design criteria shown in Table 3-2. Table 3-2. Hauled Waste Transfer Pumps Quantity 2, in parallel, 1 duty 1 standby Capacity ft Head Type Hose Pump with VFD Driven Motor August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM03 - Hauled Waste Receiving.docx

108 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water TM-4 Anaerobic Digestion Appendices 75 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

109 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 4 SUBJECT: Prepared by: Reviewed by: Anaerobic Digesters, Primary and Secondary D. Nixson M. Olivier, J. Emerson Distribution: Date: June 13, 2017 Revised on: August 11, 2017 CONTENTS I. INTRODUCTION II. DESIGN CRITERIA ATTACHMENTS: 1.) Alfa Laval Spiral Heat Exchanger Quote dated May 25, ) Alfa Laval Spiral Heat Exchanger Brochure 3.) HRS Scraping Heat Exchanger Quote dated May 25, ) HRS Unicus Series Brochure REFERENCE DRAWINGS: 1.) Alfa Laval Spiral Heat Exchanger Model 2500K General Drawing August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

110 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 I. INTRODUCTION See Technical Memorandum No. 1 for a description of the Harrisburg AWTF and the overall biosolids process. Technical Memorandum No. 4 provides summary design information regarding the primary and secondary digesters at the AWTF. The thickened sludge is transferred to the two (2) primary digesters for anaerobic digestion. The primary digesters are circular reinforced concrete tanks with sloped bottoms. The tanks are covered by fixed roofs. Anaerobic bacteria convert the volatile solids in the sludge to volatile acids, and then to carbon dioxide and methane. The gas mixture (known as digester gas or biogas) is combustible and is used to generate heat and electricity for use at the plant. Table 4-1 summarizes the existing primary digesters. Table 4-1. Existing Primary Digesters Units Clean Tank Volume 2, in parallel 1,833,000 gallons, each 3,667,000 gallons, total Diameter 90 Feet Side Water Depth 35 Feet Roof Type Fixed Mixing, Type Gas bubble eductor The contents of each digester are mixed by drawing off digester gas from the top of the digester roof, compressing the gas with a rotary lobe compressor, and then discharging it through eight (8) nozzles located approximately 1/3 below the liquid level in each of three (3) 5-foot diameter eductor tubes. The rising gas bubbles pull sludge up with them through each eductor tube and mix the tank contents. To keep the digestion process at an optimal level, the temperature in the digester should be maintained at approximately 98 F. To accomplish this, sludge is continually recirculated through heat exchangers, which are provided with hot water from the boiler house. Three (3) recessed impeller pumps pull sludge from the bottom of the digesters, circulate it through three (3) concentric tube heat exchangers and back into the top of the digesters. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

111 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 Both digesters and the associated piping and equipment have experienced vivianite (a hydrated iron phosphate mineral) precipitation and buildup. Digester No. 2 has valves which are no longer operational from vivianite accumulation, which has resulted in this digester being out of service indefinitely. Sludge from the primary digesters can be transferred by gravity to the secondary digesters. There are also two (2) progressing cavity pumps that can be used when necessary to overcome the head in the secondary digester, e.g. when lowering the level in the primary digester for maintenance or inspection. The secondary digesters are currently being used as holding tanks with no mixing or heating. Table 4-2 summarizes the existing secondary digesters. Table 4-2. Existing Secondary Digesters Units Clean Tank Volume 2, in parallel 924,000 gallons and 839,000 gallons Diameter 85 Feet Side Water Depth 28 Feet Roof Type 1 with Fixed, 1 with Floating The refurbishment of the primary digesters is currently being designed. Improvements will include: Gas mixing system replaced with mechanical mixing system Replacement of the primary digester fixed covers Replacement of the gas and sludge piping internal to the digesters Replacement of sludge piping and valves within the digester control house gallery Replacement of the waste gas flare Replacement of the primary digester recirculation pumps Replacement of primary digester transfer pumps New electrical and controls building August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

112 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 The primary digester concentric tube heat exchangers are not being modified with the current plans. The heat exchangers are sufficiently sized for the digester operation when not fouled with mineral buildup. Currently, the heat exchangers get too fouled to maintain digester temperature within months of operation. When fouled, the affected piping and heat exchanger tubes are replaced at a cost of approximately $10,000-20,000. Once the primary digesters refurbishment is completed, both digesters will be put in operation to provide additional gas production capacity. The secondary digesters will remain as holding tanks. Converting the digestion process to two-phase digestion through the addition of a single acid phase digester, should be considered, especially to provide more consistent operations when receiving the larger volumes of hauled waste in the future. This modified process, two-phase digestion, is discussed in more detail in Section II. II. DESIGN CRITERIA Digester Capacity The average operating conditions for a clean digester (i.e. no debris build up in the digester) for the primary anaerobic digesters as they are being currently operated with only one digester on line are shown in Table 4-3. Table 4-3. Current Operating Criteria for Primary Digesters, Average Flow of 19.5 MGD Primary Digesters On Line 1 Solids Loading Rate to Digester Solids Retention Time (SRT) Loading Rate 38,100 lbs TSS/day 23,700 lbs VS/day 0.13 MGD 3.0% Solids 14.4 days 0.10 lbs VS/cu ft/day 1 Average values for May 2016 to June 2017, i.e., after BNR Upgrade Start Up August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

113 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 The maximum month design criteria for the primary anaerobic digesters based on the Biosolids Facilities Improvement Plan volumes and quantities of thickened sludge are in Table 4-4. Table 4-4. Facility Planning Max Month Design Criteria for Primary Digesters (Plant Flows at 37.7 MGD) Primary Digesters On Line 1 Solids Loading Rate to Digester SRT 47,750 lbs TSS/day 36,560 lbs VS/day 0.11 MGD 5% Solids 16.7 days Loading Rate 0.15 lbs VS/cu ft/day Although the existing digester tanks are more than forty years old, after the planned refurbishment, they will be capable of operating as originally intended. With both digesters on line the digesters have the capacity to be loaded with additional solids above that expected from the primary and waste activated sludge generated by the AWTF as presented above in Table 4-4. Table 4-5 provides the full capacity of the primary digesters (assuming clean tanks). Table 4-5. Primary Digesters Design Criteria, at Full Digester Capacity Primary Digesters On Line 2 Solids Loading Rate to Digester SRT 76,900 lbs TSS/day 61,000 lbs VS/day 0.18 MGD 5% Solids 20.4 days Solids Loading Rate 0.12 lbs VS/cu ft/d Estimated Digester Capacity Available for Hauled Waste Comparing Tables 4-4 and 4-5 provides an estimate of the available capacity for hauled waste. A conservative estimate is a TS loading of 25,000 lbs/day at 80% VS, or VS loading of 20,000 August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

114 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 lbs/day. This estimated capacity assumes that there are no waste characteristics that would interfere with the digestion process, and the waste is readily degradable. The primary digester rehabilitation and improvements to WAS thickening, coupled with sludge blending and possibly two-phase digestion, would offer a conservative approach to handling the additional loading of hauled waste. With VS of 20,000 lbs/day, the hauled waste would represent about one third of the digestion loading, which is very significant. As with any biological process, a gradual increase in loading would reduce the chances of upset, until the digestion process becomes acclimated to the additional loads. It is noted that the 20,000 lbs VS/day hauled waste is based on a maximum month flow at the AWTF of 37.7 MGD, and the AWTF solids generated at this flow. If the plant flows only nominally increase over the past-three-year average flow of 21.7 MGD, to an annual average flow of 25 MGD, there would be additional capacity in the digesters for hauled waste, possibly up to 30,000 lbs VS/day. Sludge Blending Tank In order to improve digestion stability, especially with the expectation of future significant quantities of hauled wastes with variable volumes and characteristics, a sludge blending tank located ahead of digestion should be considered. The blending tank would provide mixing of thickened primary and waste activated sludges and hauled wastes to achieve a more consistent digester feed with respect to rate of feed and characteristics. This will reduce the impacts of diurnal loading variability and associated wide fluctuation in volatile solids in the feed from variable hauled waste sources. If a sludge blending tank is not included in the near term improvements, space for the tank and connections to the digestion process piping should be provided. The Improvement Plan is providing a hauled waste pretreatment facility and holding/equalization tank (TM 3). As an alternative to a separate sludge blending tank the hauled waste tank could be sized and equipped with mixing to achieve blending of the thickened plant sludges and the hauled waste. This alternative should be evaluated further. Regardless of how blending is to be achieved, it should be evaluated in conjunction with the design of the primary digester rehabilitation and evaluation of two-stage digestion and associated addition of an acid phase digester. If two-phase digestion is not implemented, or if it is planned in the future, provisions to connect the blended sludge to the primary digester feed should be included in the rehabilitation design. Two-phase Digestion (Referred to as Acid Phase Digestion in Technical Memorandum No. 1) Two-phase digestion separates the two major types of reactions that take place during anaerobic digestion, acid formation, and methane generation. Two-phase digestion would take advantage of the AWTF existing infrastructure and would allow for more effective use of the anticipated biosolids and hauled waste. Minimizing foaming in the main digesters is another of the advantages August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

115 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 of the two-phase digester. A new separate acid phase digester would be constructed sized for a solids retention time of 1-2 days where the acid formation phase of digestion would primarily take place. The feed biosolids would be pumped through a heat exchanger to increase temperature to the mesophilic range, and into the two-phase tank. The low-ph environment would be established in this digester, suspended solids would by hydrolyzed, and fatty acids would be formed. Minimal methane is generated in the acid phase digester, but any gas generated would be piped to the primary (methane phase) digester biogas system. The sludge from the acid phase digester would be pumped into the methane phase digesters which can be operated to maintain the optimum environment for methanogenic bacteria. Figure 1 illustrates a schematic incorporating two-phase digestion. Biogas Feed Sludge Hot Water Heat Exchanger Acid Phase Digester Methane Phase Digesters (Existing Primary Digesters) To Secondary Digesters (Holding Tanks) Figure 1. Schematic of Two-phase Anaerobic Digestion August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

116 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 The acid phase digester for two-phase digestion would be designed using the criteria in Table 4-6. Table 4-6. Acid Phase Digester Design Criteria Units 1 Solids Loading Rate 1.5 lbs VS/cu ft/d SRT 1.5 days Clean Tank Volume Dimensions Diameter Side Water Height 300,000 gallons 35 ft 45 ft Vivianite/Heat Exchangers The AWTF encounters significant mineral deposit buildup in the anaerobic digester recirculation/heating piping and heat exchangers. Every months the buildup becomes significant enough to cause the degradation of heat exchanger, pump and valve performance. The AWTF currently replaces the piping and heat exchanger tubes each time and, whenever this occurs, the ability to maintain the digester temperature degrades. Considering the AWTF utilizes ferric chloride for phosphorus precipitation and removal, and that the worst buildup is in the heat exchangers and the downstream piping (i.e. the hottest sludge temperatures in the system), the mineral is suspected to be vivianite, or iron phosphate. Vivianite can be identified by its characteristic blue-green color, is soluble in hydrochloric and nitric acids, and it loses solubility at higher temperatures. A single sample taken from the built up material was tested and confirmed to be characteristic of vivianite. There is currently no economical method from recovering the phosphorus from the iron phosphate. There are two primary methods to control vivianite deposits; reduce the temperature of the sludge coming out of the heat exchanger, and to reduce areas of high turbulence. Given the physical size of the primary digester pumping station there are few opportunities to address areas of high turbulence in the piping. Reducing the temperature rise of the sludge in the heat exchanger was investigated. Even when reducing the hot water temperature from 180ºF down to 140ºF, the solubility of vivianite would not be significantly improved. The base components of the existing heat exchangers (e.g. frame, shell, etc) are in good physical condition and the replacement of the heat exchangers is not currently warranted. In an effort to August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

117 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 reduce the impacts of vivianite deposits on the operations of the digesters, two alternative heat exchangers were investigated, the scraped surface heat exchanger and the spiral heat exchanger. The scraped surface heat exchanger is also a concentric tube heat exchanger similar to the existing. In addition, it has a hydraulically driven rod within the heat exchanger tubes, with scraper blades mounted along its length that extend out to the tube surface. Any buildup of material is mechanically scraped off by the reciprocating movement of the rod, and is carried away in the sludge flow. Figure 2 shows scraped surface heat exchanger mechanism. Figure 2. Unicus Series Reciprocating Scraped Surface Heat Exchanger Exploded View Credit - HRS Heat Exchangers Ltd The scraped surface heat exchanger has installations in many industries including wastewater. Design criteria for scraped surface heat exchangers can be seen in Table 4-7. Table 4-7. Scraped Surface Heat Exchanger Design Criteria Quantity 3, in parallel, 2 duty, 1 standby Heat Transfered Sludge Flow Rate Sludge Temperature Rise 733 kw 2.5 MBTU/hr 700 gpm 29 C inlet 38 C outlet August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

118 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 Table 4-7. Scraped Surface Heat Exchanger Design Criteria Water Flow 400 gpm Rate Water Temperature Rise 82 C inlet 71 C outlet Overall Length Overall Height Overall Width 21 feet 5 feet 2 feet A single budgetary quote was received for three (3) scraped surface heat exchangers from HRS Heat Exchangers Ltd, in May The bare cost of the units totaled $683,600. Without considering the cost of purchasing and installing the units, the payback when compared to the $50,000 of pipe replacement cost every 18 to 24 months, is more than 20 years. Other drivers would need to be identified to pursue the scraped surface heat exchanger. The spiral heat exchanger was also investigated. The heat exchange surface area is arranged in concentric circles, see Figure 3. Utilizing this configuration the sludge flows through a narrow passages resulting in higher velocity than in a straight tube. If buildup does occur, the velocity will increase and will help erode the buildup. Spiral heat exchangers also have a more compact footprint than concentric tube heat exchangers, and would easily fit in the existing space. Figure 3. Spiral Heat Exchanger Flow Diagrams Credit Alfa Laval The spiral heat exchangers would be designed to the criteria shown in Table 4-8. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

119 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 Table 4-8. Spiral Heat Exchanger Design Criteria Quantity Heat Transfered Sludge Flow Rate Sludge Temperature Rise Water Flow Rate Water Temperature Rise Headloss 3, in parallel, 2 duty, 1 standby 733 kw 2.5 MBTU/hr 500 gpm 95 F inlet 105 F outlet 400 gpm 155 F inlet 143 F outlet 10 feet head, maximum Overall Length Overall Height Overall Width 4 feet 5 feet 4 feet A single budgetary quote was received for three (3) spiral heat exchangers from Alfa Laval, in May The bare equipment cost of the three units totaled $125,000, compared to the $50,000 of pipe replacement cost every 18 to 24 months. A rough order of magnitude installed capital cost estimate is $400,000. The spiral heat exchanger simple payback would be approximately 12 years. Vivianite deposits could still occur in the spiral heat exchanger, and it is not possible to predict how long it would take before the deposits degrade performance. When the spiral heat exchanger does need to be cleaned, it is designed with a removable front plate for access to the heat exchanger surfaces, but the more narrow passages are more difficult to manually clean. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

120 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 4 CRW could also consider doing routine chemical cleaning of the piping systems including the heat exchangers. There are many chemicals on the market that report excellent results when removing vivianite deposits with non-toxic cleaners. The piping could be modified to make cleaning more straightforward. Steps in the cleaning cycle would include: Emptying the line of sludge, Filling line with water and chemical cleaner, Recirculate the cleaning solution, Draining the cleaning solution. Another consideration would be to change phosphorus precipitant to an aluminum salt, rather than the ferrous salt they are currently using. Aluminum salts tend to be more expensive than ferrous salts. The change to an aluminum salt would eliminate vivianite, but may have other unintended mineral buildup consequences. Modifying the liquid treatment process to utilize biological phosphorus (Bio-P) removal should also be mentioned. If the AWTF were converted to Bio-P, the phosphorus could be removed from the waste activated sludge and recovered as a sellable product. Converting the AWTF to Bio-P would require the installation of an anaerobic zone prior to the pure oxygen tanks. The anaerobic zone would be designed for a hydraulic retention time of 1 to 1.5 hours, or 1.5 to 2.3 million gallons volume. A final alternative considered is direct steam injection into the digesters. A steam generator would be required, as would multiple steam injection lances mounted on the roof of each digester. Direct steam injection has been used successfully for many years at the City of Baltimore Back River WWTP. In Phase 1 Primary Digester Improvements, steam lances will be constructed into the primary digesters. This will eliminate the heat exchangers from the recirculation loop. Further investigation and evaluation along with discussion with CRW is recommended to determine the alternative that addresses their priorities most effectively. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM04 - Anaerobic Digestion.docx

121 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water TM-5 Hauled Waste Appendices 76 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

122 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 5 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 5 SUBJECT: Co-Digestion Market Assessment for Capital Region Water Prepared by: L. Boudeman, K. Turner Reviewed by: T. Johnston Distribution: Date: June 15, 2017 Revised on: August 11, 2017 August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

123 Table of Contents 1.0 BACKGROUND INTRODUCTION GOALS AND OBJECTIVES EXISTING CONDITIONS CURRENT HAULED WASTE PROGRAM BIOGAS PRODUCTION HIGH STRENGTH WASTEWATER SURCHARGE FEE SCHEDULE MARKET ASSESSMENT APPROACH CONSIDERATIONS FOR PARTICIPATION IN HAULED WASTE PROGRAMS Transportation/Hauling Costs Competition from Other Municipal WWTPs High Strength Wastewater Surcharge Fees Non-municipal Anaerobic Digesters...13 On-Farm Digesters Kline s Septic Services Direct Land Application Programs IDENTIFYING HIGH STRENGTH WASTE GENERATORS MARKET ASSESSMENT MARKET ASSESSMENT FINDINGS HIGH STRENGTH WASTE GENERATORS Airport Breweries/Distilleries Candy Dairy Fats, Oils, and Grease Slaughterhouse/Meatpacking Snack Foods FINDINGS AND RECOMMENDATIONS FINDINGS DIGESTER CAPACITY PROMISING FEEDSTOCKS Grease Trap Waste from Area Restaurants...26 TM05 - WRA_CRW_Co-digestion Market Assessment.docx

124 DAF Solids / FOG from dairies, snack food processors / candy processors Potential volumes and biogas production Operational limitations RECOMMENDATIONS Establish infrastructure for receiving hauled waste Utilize grease trap waste ordinance Follow up with identified facilities and haulers Develop experimental introduction plan Pricing Strategies Revisions needed to update the hauled waste program...31 REFERENCES...32 APPENDIX 1. IDENTIFIED HSW DISCHARGERS...33 APPENDIX 2. SURVEY APPROACH...36 Figures Figure 1. Process hauled waste vs. digester gas production January 1, 2016 to April 1, Figure 2. Hauled waste categories accepted at utilities in southcentral Pennsylvania Figure 3. Hauled waste tipping fees for utilities in Southcentral Pennsylvania Figure 4. Potential HSW feedstocks were identified within a 50-mile radius of CRW AWTF Figure 5. Food Processing and Industrial Facility Wastewater Handling and Management Practices Tables Table 1. Hauled waste accepted at the CRW AWTF in 2016 and corresponding revenue... 6 Table 2. Hauled waste accepted at the CRW AWTF in 2017 and corresponding revenue... 7 Table 3. Maximum concentration of hauled waste constituents allowable... 7 Table 4. Hauled waste general limitations... 8 Table 5. CRW High Strength Waste Fee Surcharge Concentration Limits... 9 Table 6. Estimated Transportation Costs for Hauled Waste Table 7. Co-Digestion Feedstock Generator Categories Table 8. Typical ADF and AAF Runoff Characteristics Table 9. Wastewater characteristics of a sweetener processing facility August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

125 Table 10. Candy processing facilities within 50 miles of CRW AWTF Table 11. Waste characteristics of a dairy processing facility Table 12. Dairy processing facilities within 50 miles of CRW AWTF Table 13. Hershey Creamery Waste Parameters Table 14: Characteristics of Grease Trap Waste Table 15. Estimated GTW generated in the City of Harrisburg Table 16. Major sources of slaughterhouse/meatpacking wastewater Table 17. Meat Processing Typical Wastewater Characteristics Table 18. Meatpacking facilities within 50 miles of CRW AWTF Table 19. Wastewater characteristics of UTZ DAF solids Table 20. Snack-processing facilities within 50 miles of CRW AWTF Table 21 Full Scale GTW Co-Digestion implementations (Long, 2012)Error! Bookmark not defined. Table 22. VSS Loadings from selected HSW generators Table 23. Ratio of GSW to sludge at selected loadings August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

126 1.0 Background 1.1 Introduction This Technical Memorandum is submitted in accordance with the scope of work outlined in Task Order 3, dated July 16, 2015, between Whitman, Requardt, and Associates (WRA) Inc. and Material Matters, Inc. (MM). This memorandum presents the findings of a Co-Digestion Market Assessment conducted on behalf of Capital Region Water (CRW), which owns and operates the Harrisburg Advanced Wastewater Treatment Facility (AWTF). CRW initiated the market assessment to identify regionally available high strength wastes (HSW) from industrial and nonresidential dischargers suitable for co-digestion in the anaerobic digestion process at CRW Advanced Wastewater Treatment Facility (AWTF), located in Harrisburg, PA. The AWTF serves the city of Harrisburg and surrounding area, and operates with an average daily flow of approximately 22 million gallons per day (mgd). The facility also accepted approximately 4.6 million gallons of hauled-in waste in Under current operating conditions, solids from the primary sedimentation tanks are blended with waste activated sludge (WAS), thickened in a gravity thickener, digested in a primary anaerobic digester, stored in a secondary digester, and dewatered with a belt filter press (BFP). The anaerobic digestion process generates biogas, which is stored and can be utilized to power two 400 kw turbine generators, three heat exchangers, and two boilers. CRW has operated engine generators since An agreement between the CRW and PPL Electric Utilities gives CRW the ability to export energy in excess of the plant s needs to the power company to generate revenue. However, as noted in the Existing Conditions report, aging and inoperable infrastructure has inhibited the AWTF from maximizing gas production and has curtailed the conversion of biogas into energy. 1.2 Goals and Objectives CRW initiated an AWTF Biosolids Facilities Improvement Plan to assess the current condition of the solids handling equipment, and to identify and evaluate alternatives for improvements for each major solids processing step. In the Existing Conditions report, MM noted a need to achieve volatile solids destruction to meet process Vector Attraction Reduction (VAR). An added benefit is that biogas production will be improved. Infrastructure upgrades will improve volatile solids destruction, increase biogas generated in the AD, and will allow the AWTF to expand its existing hauled waste program to include HSW. This memorandum has been prepared to evaluate the potential to accept additional HSW streams to better utilize available digestion process capacity, offset operating costs, and increase biogas production. HSW includes a number of materials sourced largely from food and beverage production and processing facilities, such as food processing wastes, off-spec beverage products, dairy wastes, brewery wastes, and fats, oils, and grease (FOG). Typically, these waste streams are highly biodegradable, have higher volatile solids content than municipal wastewater solids, and can increase biogas production if digested along with the solids produced or received at the Wastewater Treatment Plant (WWTP) (USEPA, 2014). Material Matters evaluated the regional availability of these HSW streams. To complete the assessment, it is important to understand CRW s current hauled waste and industrial pretreatment program, characterize current hauled waste management and beneficial use practices by the August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

127 industrial and non-residential dischargers in the region, and define the economic model for accepting a particular waste stream. 2.0 Existing Conditions 2.1 Current Hauled Waste Program CRW maintains a moderately sized hauled waste program. Between January 2016 and April 2017, CRW accepted between 133,000 and 667,500 gallons of hauled waste per month (Tables 1 and 2). On average, CRW accepted ~384,150 gallons per month in 2016; in 2017, this average increased to ~602,900 gallons per month. The increase is primarily due to initiating the acceptance of dissolved air flotation (DAF) solids from UTZ Quality Foods (UTZ) in February 2017 through May of CRW categorizes hauled waste into two categories: Process and Septic. Process includes high solids material from municipal wastewater treatment plants, mobile home parks, food processing plants and landfill leachate, whereas Septic includes wastewater from septic and holding tanks. CRW does not accept grease trap waste (GTW), medical/infectious/or biohazard waste priority pollutant waste, characteristic or listed hazardous waste, or digester, lagoon or tank cleaning waste or grit. Table 1. Hauled waste accepted at the CRW AWTF in 2016 and corresponding revenue Process Septic Total Month Gallons Revenue Gallons Revenue Gallons Revenue January 479,600 $15, ,000 $1, ,600 $16, February 439,700 $14, ,000 $ ,700 $15, March 451,660 $14, ,000 $3, ,660 $17, April 261,760 $9, ,000 $2, ,760 $12, May 245,380 $8, ,500 $1, ,880 $10, June 133,580 $4, ,000 $1, ,580 $6, July 202,839 $7, ,500 $2, ,339 $9, August 160,800 $5, ,000 $2, ,800 $8, September 397,500 $17, ,500 $2, ,000 $19, October 341,500 $12, ,000 $3, ,500 $15, November 240,980 $9, ,000 $2, ,980 $12, December 504,020 $17, ,000 $1, ,020 $19, Total 3,859, , ,500 $27, ,609,819 $164, Month Avg. 321,610 11, ,542 $2, ,152 $13, August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

128 Table 2. Hauled waste accepted at the CRW AWTF in 2017 and corresponding revenue Process Septic Total Month Gallons Revenue Gallons Revenue Gallons Revenue January 464,600 $16, ,000 $1, ,600 $17, February 667,500 $23, ,000 $ ,500 $24, March 498,400 $19, ,000 $1, ,400 $20, April 639,140 $26, ,000 $2, ,140 $28, Total 2,269,640 $85, , $5, ,411,640 91, Month Avg. 567,410 $21, ,500 $1, ,910 $22, At present, CRW has a list of 36 registered hauled wastes to the AWTF; the majority (26 of 36) comes from municipal wastewater treatment plants (e.g. lower-strength waste streams). The other waste streams include wastewater from one compost facility, one mobile home park, two foodprocessing facilities, two landfills, two restaurants/service facilities, and two septic haulers. Most hauled waste is accepted at the headworks; however, the UTZ DAF solids are accepted at the thickener just prior to the anaerobic digester. Discharging directly to the anaerobic digester or slow feeding to the digester is the typical approach to process HSW. However, the infrastructure for direct feed and equalized flow does not currently exist at the AWTF. CRW has established hauled waste acceptance requirements. Prior to hauling the first load of waste to CRW, the waste generator must complete the following requirements: 1. An application form from the hauled waste source; 2. A $50 application fee; 3. A waste sample for analysis in a CRW sample container ($299 fee), and 4. Supplemental results of sampling and testing. Once the wastewater is analyzed and approved (based on Table 3 and Table 4 limits/criteria), CRW issues a one-year contract. During the first month of hauling, wastewater generators are charged a discharge fee based on percent total solids (%TS) at $0.009/every 0.5% TS; the minimum fee is $0.027/gallon and 1,000 gallons. For months two through twelve of the contract, discharge fees are charged per truckload. In addition, a surveillance analysis is completed for every 200,000 gallons, or once per year for those under 100,000 gal/year for a fee of $ Table 3. Maximum concentration of hauled waste constituents allowable Parameter Cadmium, Total Chromium, Total Copper, Total Lead, Total Mercury, Total Nickel Total Zinc, Total Concentration (dry wt. basis) 39 mg/kg 1,200 mg/kg 1,500 mg/kg 300 mg/kg 17 mg/kg 420 mg/kg 2,500 mg/kg August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

129 Table 4. Hauled waste general limitations Parameter Limit ph TVS 55% minimum Oil/Grease 100 mg/l Ammonia Nitrogen 500 mg/l 2.2 Biogas Production In general, co-digestion with HSW enhances biogas production relative to digestion of municipal wastewater solids alone. Digester gas production directly corresponds to the levels of Process hauled waste accepted at CRW (Figure 1). CRW experienced a decline in hauled waste in mid (equipment failures) that resulted in a decline in gas production. Data available through April of 2017 shows that gas production is improving as more hauled waste is incorporated into the program. The addition of UTZ DAF solids in early 2017 led to some operational challenges with the digester (foaming), and will need to be addressed as more hauled waste is accepted and added directly to the digester. Section 5 includes discussion about challenges with HSW added directly to the digesters. It is assumed that increasing the volume of HSW, in conjunction with solids handling upgrades, will increase biogas production at the AWTF. Capital Region Water Process Hauled Waste vs. Digester Gas Production Process Wastewater (gallons) Gas Production (cubic feet) 0 0 1/31/2016 3/31/2016 5/30/2016 7/29/2016 9/27/ /26/2016 1/25/2017 3/26/2017 Process Wastewater (Gallons) Gas Production (cu. Ft.) Figure 1. Process hauled waste vs. digester gas production January 1, 2016 to April 1, High Strength Wastewater Surcharge Fee Schedule Capital Region Water has an active high-strength wastewater surcharge program, which is a fee charged to dischargers of higher-than-domestic strength wastewater to recover the higher cost associated with treating these wastes. CRW s high-strength wastewater surcharge schedule is found in Table 5. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

130 Table 5. CRW High Strength Waste Fee Surcharge Concentration Limits Parameter Surcharge Level (mg/l) Harrisburg Customers ($/1,000 gallons) Harrisburg Conveyance System ($/1,000 gallons) Steelton Conveyance System ($/1,000 gallons) BOD 290 $0.15 $0.15 $0.11 SS 380 $0.11 $0.11 $0.11 TP 10 $2.18 $2.21 $2.21 Surcharges are expressed as cents per volume of water consumed for each mg/l by which the pollutant exceeds the threshold. For example, if an industry discharges 1,000,000 gallons of wastewater with a BOD of 300, it would be charged 1,000 * $0.15 * ( ), or $1,500. Surcharge rates (per 1000 gallons) are determined for the current year based on the prior year s laboratory analysis. For example, 2017 surcharge rates for specific companies would be based on BOD, SS, and TP from With an active high-strength wastewater surcharge program, there is incentive for significant industrial users in the CRW s service area to divert high strength wastewater out of the collection system and haul waste directly to the AWTF or other processing facilities. One industrial discharger MM interviewed, Hershey Creamery, discharges 65,000-70,000 gallons of wastewater to the collection system every day at the rate of $4.27/1000 gallons. At this rate, Hershey Creamery pays CRW approximately $300/day as a surcharge. If there is an economic incentive to encourage Hershey Creamery to haul waste directly to the digester, they stated that they would be very interested. Harrisburg Dairies is another dairy in the CRW service area that may be interested in diverting waste out of the CRW collection system to the digester. Additionally, several food processors, including Hershey Creamery, remove 3,000 gallons per day of DAF solids and divert them to other digester facilities or land application. Capturing this HSW for addition to the CRW digesters, if priced appropriately, would provide a benefit to both Hershey Creamery and CRW. 3.0 Market Assessment Approach 3.1 Considerations for Participation in Hauled Waste Programs There are factors that must be considered when evaluating a generator s potential participation in a co-digestion program. Important considerations for HSW generators include transportation/hauling costs, proximity to other municipal wastewater treatment plants (WWTPs) that accept hauled wastes, high-strength wastewater surcharge fees, direct land application programs, and options for on-farm anaerobic digesters Transportation/Hauling Costs Material Matters interviewed waste haulers to understand typical transportation and hauling costs, and to establish an economically viable radius appropriate to transport waste streams. Waste haulers choose where to haul wastes based on economic incentives, and the availability and location of processing facilities. Waste haulers develop their fee schedule based on loading (merge), unloading (demerge) and transport times rather than wastewater volumes hauled or August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

131 distance transported, because the majority of their expenses are in labor and insurance. Rates typically range between $100 and $120 per hour. For the majority of liquid waste streams, a maximum economically-viable hauling cost is $0.03 to $0.05 per gallon; transportation fees that exceed this value create a combined tipping/transportation fee that typically exceeds other locally available outlets. Table 6 shows that the tipping fee of $0.03 to $0.05 per gallon is equivalent to a one-hour, one-way transport. Therefore, assuming an average speed of miles per hour, the maximum one-way radius for most waste streams is ~30-60 miles. However, haulers reported that waste streams with characteristics that are more difficult to treat (i.e. exceptionally high BOD, TSS, or other pollutant concentrations) are often hauled farther distances (50+ miles) to be processed. Table 6. Estimated Transportation Costs for Hauled Waste Hours Costs (One Way) (Round Trip) (Demerge) Full Charge Cost per Gallon $200 $ $300 $ $500 $ $700 $ $900 $0.15 An economically viable hauling cost of $0.03-$0.05 per gallon is generally accepted, and most waste haulers will participate at CRW if HSW generators are located no more than one-hour (50 miles) away. For this assessment, a radius of approximately 50 miles was assumed to be the maximum hauling distance for most waste streams. In particular, Material Matters interviewed JG Environmental, a waste hauling company based in Lancaster that has an established partnership with CRW. JG Environmental expressed interest in hauling HSW to CRW in the future and mentioned that contracts for high-bod waste materials were recently available. They suspect that similar opportunities would become available in the future and are looking forward to developing this business opportunity with CRW Competition from Other Municipal WWTPs The competition for hauled waste revenue is a factor to be considered when expanding a hauled waste program. When evaluating the regionally available hauled waste streams, it is critical to consider the details of other management and beneficial use options available to HSW generators, including location and tipping fees. A 2013 survey conducted by MM showed that, in addition to CRW, at least 11 municipal wastewater treatment plants in central/southern Pennsylvania accept hauled waste. Figure 2 shows the waste stream categories accepted by these facilities. The other category includes high solids food waste, printing ink, meat-processing waste, and car wash waste. Note that CRW participated in this survey. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

132 Hauled-in Waste Categories Accepted Number of Facilities Septage Holding Tank Waste Portable Toilet Waste Leachate Solids FOG Industrial Other Categories of Hauled-In Waste Figure 2. Hauled waste categories accepted at utilities in southcentral Pennsylvania Of the 11 utilities surveyed, less than half accept HSW: three accepted FOG, five accept industrial waste, and three accept other HSW. Although the facilities that accept HSW are limited in number, some of these facilities are within 50 miles radius of CRW. Derry Township Municipal Authority (DTMA), located only 15 miles east of CRW, has a robust hauled waste program, but limited digester capacity. DTMA uses biogas to generate power for their thermal dryer and heat for the plant. The Manheim Area Water and Sewer Authority, located approximately 30 miles east of the CRW, also has a very robust hauled waste program, accepting more than one million gallons of hauled waste each month. The Lancaster Area Sewer Authority, located approximately 40 miles southeast of the AWTF, plans to accept hauled waste by the end of 2018, which will be additional competition for CRW. The tipping rates for each waste category varied considerably among the surveyed facilities. The primary billing method for all waste streams (except solid wastes) is a flat rate of dollars per 1,000 gallons. For high solids materials, however, most surveyed facilities have a fee schedule based on the percent total solids of the material. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

133 $ $ Average Minimum Hauled-in Waste Billing Rates (dollars/1000 gallons) $91.14 $ $ $ $95.00 Billing Rate (dollars/1000 gallon) $80.00 $60.00 $40.00 $20.00 Maximum $50.00 $50.00 $33.38 $23.70 $24.21 $11.00 $69.00 $38.41 $22.50 $19.95 $35.70 $56.35 $35.60 $48.67 $15.00 $0.00 Septage Holding Tank Waste Portable Toilet Waste $0.04 Leachate Solids* FOG Industrial Hauled-in Waste Categories *Solids numbers are only for facilities that charge a set rate for high solids waste streams. Figure 3. Hauled waste tipping fees for utilities in Southcentral Pennsylvania CRW s HSW fees of $0.027 per gallon ($27 per 1,000 gallons) is comparable to the average fees for septage, holding tank waste, portable toilet waste, and leachate. If CRW decides to accept HSW (including FOG) in the future, the average price in the region is about four times higher than the CRW s current septage rate. Note that the value of the HSW (for biogas production) must also be considered when setting tipping fees High Strength Wastewater Surcharge Fees As discussed in section 2.3, wastewater discharged from non-residential dischargers (categorized as industrial, institutional, or commercial) can have higher levels of Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Total Phosphorus (TP), or Total Nitrogen (TN) than domestic wastewater and will require a higher level of treatment. On a volume basis, high strength industrial, institutional, and commercial wastewaters cost more to treat than residential wastewater because it has a higher oxygen demand, creates more solids to manage, and requires more chemicals for treatment. A high-strength wastewater surcharge program provides utilities with a mechanism to recover the additional treatment costs created by these discharges by charging a surcharge fee (in addition to the quarterly user rate) to dischargers of high strength wastewater, when discharged to the head of the plant. Surcharge rates provide an equitable means of distributing treatment costs among ratepayers based on discharge characteristics. They are facility-specific and are calculated based on actual facility operating data. By establishing high-strength surcharge rates, WWTPs have the ability to distribute treatment costs based on actual discharge strength above an established surcharge baseline concentration. Effective HSW surcharge programs provide an economic incentive for HSW dischargers to pretreat their wastewater or haul waste streams off-site, rather than directly discharge into the August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

134 collection system. A facility that directly discharges high strength wastewater into the sewer system, but is not subject to any HSW surcharge fees has no economic incentive to divert the wastewater for co-digestion. In contrast, a generator faced with HSW surcharge fees may find cost savings by paying to haul the wastewater off-site. Because the CRW has adopted a HSW surcharge program, industry subject to these surcharges will be more inclined to divert HSW to the anaerobic digester at the AWTF, rather than directly discharge into the collection system. For example, Hershey Creamery, located in the CRW service area, hauls HSW (subject to the CRW surcharge and FOG limits) to the Kline s anaerobic digester in Landisville. Co-digestion of HSW generated in the service area of the AWTF, particularly when a surcharge program is being implemented, provides an opportunity to remove these wastes from the collection system and divert them directly to the digester. As noted, the infrastructure to manage HSW feed to the digester is not in place, such as a receiving station and flow equalization. In addition, a codigestion program that provides incentives (e.g., pricing, revising discharge limits) to HSW generators in their own service area, if the HSW has appropriate characteristics, should also be considered Non-municipal Anaerobic Digesters Non-municipal digesters include digesters located on farms (manure anaerobic digesters) and anaerobic digesters operated by contract haulers (e.g., Kline s Septic Service). On-Farm Digesters Beginning in the mid-2000 s, Pennsylvania farms had financing available from the state and federal government for the construction of anaerobic digesters as a Best Management Practice for manure management. The funding sources include USDA s REAP (Rural Energy for America Program), stimulus dollars from U.S. Treasury grants, and state financing assistance from both PennVest (the Commonwealth Financing Authority) and the Pennsylvania Department of Environmental Protection (PADEP). Most farms with on-farm digesters have generators to utilize the biogas to produce electricity and heat. In order to maximize energy production and fill excess capacity in the manure digesters, some farms choose to supplement their manure digester with food processing waste. The PADEP issued a general permit WMGM042 that allows anaerobic digestion of animal manure on a farm mixed with grease trap waste (collected from restaurants or grocery stores) and pre-consumer and postconsumer food waste from commercial or institutional establishments. Farm digesters within the Harrisburg region include: Brubaker Farms: Mount Joy, PA Keefer Hard Earned Acres: Shippensburg, PA Sensenig Dairy: Kirkwood, PA Oak Hill Farm: Avella, PA Farm manure anaerobic digesters typically offer a competitive tipping fee because they received financial support from grants, and they are located at the land application site (for digestate). Kline s Septic Services Kline s Services is a wastewater hauling / management company headquartered in Landisville, PA. Kline s owns and operates an anaerobic digester with capacity to accept and process up to 50,000 gallons per day of high strength wastewater. Kline s operates under a WMGR099, which August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

135 allows them to accept, process, and beneficially use (by land application) a combination of domestic sewage and industrial wastewater treatment sludge. Kline s hauls wastewater solids to both their own anaerobic digester and to other municipal wastewater treatment facilities. Kline s generally hauls higher strength waste (e.g. dairy, bakery, and FOG) to their own anaerobic digester to maximize gas production, and lower strength solids (e.g. municipal solids) to other municipal wastewater treatment plants. Hershey Creamery, located in Harrisburg, PA, and Turkey Hill, located in Conestoga, PA, reported that Kline s accepts their high strength waste (e.g., FOG) for a very competitive combined transportation / tipping fee of $0.05 or less per gallon Direct Land Application Programs The food processing industry commonly recycles food processing wastewater and wastewater solids as animal feed and as fertilizer. In Pennsylvania, land application of food processing residuals (FPR) is covered under PA Code Chapter 283. Facilities that wish to land apply FPR are covered by a permit-by-rule as long as they follow practices found in PADEP s Food Processing Residual Management Manual. Southcentral Pennsylvania is a highly active agricultural area, with a significant acreage devoted to row cropping and a high animal population; as such, land application of FPR is a readily accessible, low-cost management option. Programs are typically arranged in one of the following ways: The farmer hauls and spreads the food processing residual for free (or farmer pays for the product) The food processor pays for transportation; farmer accepts FPR for free The food processor pays for transportation; farmer is paid a management fee. Due to the close proximity to agricultural land, the ease of the regulatory program, low transportation costs, and low tipping fees, land application is a significant competitor to anaerobic digestion. Industries utilizing land application as a waste management option typically require an alternative avenue for waste removal in winter months when the ground is frozen. Several of the food processers Material Matters interviewed indicated that they use the services of a waste hauler such as Kline s Septic Services during conditions when land application is not practical. 3.2 Identifying High Strength Waste Generators MM identified a list of potential HSW generators within a 50-mile radius of the CRW AWTF, which includes most of southcentral PA, and a portion of northern Maryland (Figure 4). August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

136 Figure 4. Potential HSW feedstocks were identified within a 50-mile radius of CRW AWTF The following resources were utilized to identify potential HSW generators: 1. Internet searches 2. Liquid waste hauler lists 3. Consultants from an industrial wastewater treatment firm Potential HSW generators were divided into ten categories; a summary of the HSW generators is provided in Table 7. A detailed list of the identified facilities is included in Appendix 1. Table 7. Co-Digestion Feedstock Generator Categories Category Airport Animal Feed Bakery Brewery Candy Canned Food Dairy Distillery Fats, Oils, Grease Food Production Facilities Slaughterhouse/meatpacking Fresh Vegetable Packing Snack foods August 2017 TM05 - WRA_CRW_Co-digestion Market Assessment.docx 15 No. of HSW Generators See Material Matters, Inc.

137 3.3 Market Assessment Industrial and food processing facilities generate multiple waste streams that can be managed in a variety of ways. These facilities balance costs, risks, and environmental impacts when deciding how each waste stream should be treated, transported, and utilized. Figure 5 depicts the potential waste streams generated, handling / processing options, and disposal or beneficial use outlets. Waste streams include wash water from cleaning activities, off-spec products (contaminated, damaged, or expired), excess raw materials, and wastewater treatment products such as high strength side streams and DAF thickener solids. Facilities can discharge wastewater to the sewer (either with or without pretreatment), treat and discharge wastewater into a receiving water body, or haul material off-site to be beneficially used, disposed, or further processed. Potential HSW Streams Cleaning Activities Off-Spec Products Raw Materials DAF, HS side streams Handling Discharge to Sewer Pretreatment (& discharge to sewer) NPDES Permit (w/ direct discharge) Hauled off-site Disposal / Beneficial Use Municipal WWTP Receiving Waters Beneficial use (fertilizer, animal feed) Other post processing (WWTP, commercial processing) Landfill Disposal Figure 5. Food Processing and Industrial Facility Wastewater Handling and Management Practices In order to solicit information from sources of high strength wastewater, MM developed survey questions for each waste streams produced by the processing facilities (Appendix 2). Questions were developed to obtain information in the following areas: 1. Quantity of high strength wastewater generated; 2. High strength wastewater characteristics; 3. Current handling practices; and 4. Willingness to participate in an alternative program. 4.0 Market Assessment Findings 4.1 High Strength Waste Generators A description of HSW generators within the CRW region, and typical waste stream characteristics and energy values are described below August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

138 4.1.1 Airport Airports utilize aircraft deicing fluids (ADF) and aircraft anti-icing fluid (AAF) during winter weather conditions. Chemicals such as ethylene or propylene glycol, urea, potassium acetate, sodium acetate, sodium formate, calcium magnesium acetate, or an ethylene glycol based fluid are also to clear airport paved surfaces (e.g. runways, taxiways, and gate areas). ADFs are used for the removal of snow, ice, and frost from the exterior surfaces of aircrafts. ADFs are heated and applied directly onto aircraft surfaces immediately preceding takeoff. During times when there is active winter precipitation (e.g. snow, sleet, and freezing rain), AAF is applied directly after the ADF to provide production against new buildup of snow and ice. Alternatively, AAF can be applied to a dry aircraft to prevent overnight frost from accumulating. The run-off from airport surfaces is typically collected and treated to reduce the potential toxicity of these chemicals from affecting waterways. Other contaminates that may be found in industrial wastewater from an airport, in addition to deicing/anti-icing fluids, are spilled fuel, lubricants, and wastewater from vehicles/aircraft. Airports may either treat this wastewater on-site or discharge it to a municipal sewer system for treatment. Harrisburg International Airport is less than seven miles from the Harrisburg AWTF. While it is not clear if / how the deicing fluid at the HIA is treated, transport of spent fluid to the CRW AWTF is an excellent opportunity. The base chemical of ADF and AAF is propylene or ethylene glycol, typically accounting for more than 80% of the total product volume. ADF and AAF also contain a mix of water, corrosion inhibitors, wetting agents, thickeners and typically contain dye. As shown in Table 8 glycol exerts a high biochemical oxygen demand. According to the EPA, it is estimated that the majority of ADF and AAF is discharged to surface waters (21 million gallons per year), and only a small fraction is treated by municipal treatment plants (2 million gallons per year). Due to the high COD content, deicing wastewater is a good candidate for co-digestion. Studies have shown that propylene glycol can be easily degraded under anaerobic conditions (Veltmen et al, 1998). Some additives in deicing fluids, such as methyl-benzotriazole (MEBT), however, can be inhibitory to methanogenic bacteria at concentrations above the toxicity threshold. Studies have found that the addition of airport deicing wastewater to anaerobic digesters generally yields benefits, including increased biogas production (Zitomer et al, 2001). Because of the various constituents that can be found in this type of runoff, CRW may wish to first conduct treatability studies of the Harrisburg International Airport s wastewater prior to introduction to the digesters. This market may be viable; however, the volume of deicing fluids generated at the Harrisburg International Airport is unknown and will require additional follow-up. Table 8. Typical ADF and AAF Runoff Characteristics Parameter Concentration BOD5 100 to 1,000,000 mg/l COD 31,300 mg/l Glycol 17,200 mg/l ph 7.50 to 9.3 s.u. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

139 4.1.3 Breweries/Distilleries Breweries generate two categories of waste in the brewing process washwater and solids. Typically, smaller breweries (5,000 barrels or less per year) neutralize acidic wash water with baking soda or caustic and discharge directly into the collection system. Large breweries typically discharge into their own pretreatment or wastewater treatment plant. Breweries report generating between 5 and 10 gallons of wastewater per barrel of beer brewed. The solid stream consists of spent grain, hops, and yeast; this material is typically collected by local farmers, hauled off site at no cost to the brewer or distiller, and used for animal feed. Based on interviews with a brewery (Appalachian Brewing Company, Harrisburg) and a distillery (Mid-State Distilling, Harrisburg), this appears to be standard for the industry. Ten distilleries and 33 breweries were identified within 50 miles of the CRW AWTF. Overall, this market does not appear viable for co-digestion due to the low volumes of wastewater generated by each source, and the low-cost accessibility to local agricultural markets Candy Candy manufacturing includes production of chocolate, hard candies, soft gummy or chewy candies, and other confectionaries. Process wastewater from these facilities is typically generated during the first flush of the washing process. In some cases, a demand for high strength sugar water exists, in which case a portion of the wastewater can be segregated for other uses and a source of revenue for the manufacturer. In the case of chocolate, peanut, or other fat-containing candies, process water from a candy manufacturing process will include a film of FOG that will float to the surface, or will be emulsified into the water. Free FOG will be scraped off and beneficially used or disposed. In contrast, emulsified FOG will be treated with a coagulant to flocculate the FOG for removal from the wastewater; this is typically performed in a dissolved air flotation (DAF) unit. Characteristics from a processing facility of sweeteners (e.g. corn syrup, dextrose, molasses, etc.) are found in Table 9. Table 9. Wastewater characteristics of a sweetener processing facility Parameter Concentration ph 4 5 s.u. BOD 15,000 to 60,000 mg/l TS 3-8% MM identified and contacted 11 candy-manufacturing facilities within 50 miles of the CRW AWTF facility (Table 10). One facility operates their own wastewater treatment plant, one is starting a land application program, one uses Kline s hauling services, and eight facilities did not respond. The Warrell Corporation currently separates DAF solids, which is then hauled out by Kline s. They produce 9,200 gallons of DAF solids every three to four weeks. The candy market has limited potential; however, follow up with the facilities that could not be reached is recommended. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

140 Table 10. Candy processing facilities within 50 miles of CRW AWTF Company Location Recommendation Blommer Chocolate Co East Greenville Potential; Contact again Cargill Cocoa and Chocolate Mount Joy Potential; Contact again Fitzkee's Candies York Very Small; not viable Gardner's Candies Tyrone Potential; Contact again Hershey Hershey Potential; Contact again L&S Sweeteners Leola Operate low cost land application program; not viable Mars Chocolate Elizabethtown Operate own WWTP; not interested RM Palmer Co. Reading Potential; Contact again Warrell Corporation Camp Hill DAF Solids hauled by Kline s; Potential; Contact again Wolfgang Candy Company York Potential; Contact again Y&S Candies Lancaster Potential; Contact again Dairy Dairy processing includes the processing and production of a variety of products including fluid milk, butter and butter spreads, yogurt, and ice cream and frozen dessert producers. In southcentral Pennsylvania, dairy processing facilities manufacture iced tea and other beverages as well. Dairy processing facilities typically have an on-site pretreatment facility followed by discharge into the municipal collection system or an on-site treatment facility with direct discharge into a receiving water body (i.e. NPDES Permit). There are two dairy processing facilities registered as significant industrial dischargers in the CRW service area (Harrisburg Dairies and Hershey Creamery). High strength waste products from dairy processing facilities include first flush wash water, acid whey, off-spec/damaged products, and surplus of raw product. Facilities with on-site processing also generate high-energy solids from the DAF process, and solids digestion processes. Fluid milk and DAF solids are an effective COD source if added directly into an AD. Typical wash water characteristics from a dairy processing facility are found in Table 11. Table 11. Waste characteristics of a dairy processing facility Parameter Wastewater from Products Milk Fluid Products Dry Products ph (s.u.) COD(mg/L) 1,794 2,270 2,391 TN(mg/L) TP (mg/l) Oil & Grease (mg/l) Dairy processing waste is typically utilized in agriculture as animal feed or as a soil amendment. During winter months when the ground is frozen and/or snow covered, however, land application August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

141 is limited. Dairy processors and waste haulers have reported that they need alternative outlets during these times. MM contacted twelve dairy processing facilities within 50 miles of the CRW AWTF. A summary of the dairy processing facilities is found in Table 12. Table 12. Dairy processing facilities within 50 miles of CRW AWTF Company Location Recommendation Land O' Lakes Carlisle Potential; Contact again Cumberland Valley Creamery Mechanicsburg Potential; Contact again Harrisburg Dairy Harrisburg DAF Solids; Potential; Contact again Clover Farms Dairy Reading Potential; Contact again Kreider Dairy Manheim Operate own digester; not viable Swiss Premium Lebanon Potential; Contact again Rutters York Potential; Contact again Hershey Creamery Company Harrisburg DAF Solids hauled by Kline s; Potential; Contact again Dairiconcepts Hummelstown Potential; Contact again Schreiber Foods, Inc. Shippensburg Potential; Contact again Dairy Farmers of America Mechanicsburg Potential; Contact again Turkey Hill Conestoga DAF Solids hauled by Kline s and JG Environmental: Potential; Contact again MM interviewed Hershey Creamery, one of the significant industrial dischargers in the CRW service area. CRW limits FOG to 100 ppm in discharged wastewater, and as a result, Hershey Creamery responded by establishing a treatment program to remove DAF solids from the wastewater before discharging to CRW. The DAF solids are hauled out by Kline s Septic Services for $300 per load ($0.05 per gallon). They typically produce 6,000 gallons of DAF solids every two days. Hershey Creamery expressed interest in utilizing CRW as an option for their FOG if there is an economic incentive. This market appears to have potential when considering two dairies in the service area, and the number of other dairies locally. Characteristics of both the FOG and the surcharged wastewater are included in Table 13. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

142 Table 13. Hershey Creamery Waste Parameters Parameter FOG Characteristics 1 Discharged Wastewater Concentrations 2 Daily Volume 3,000 gal 65-70,000 gal Total Suspended Solids (mg/l) 238, ph Hexane Extractable Oil and Grease n/a <5.45 BOD5 n/a 4015 Total P n/a 5.9 TVS% 98% n/a 1 FOG Characteristics provided from a single 6/3/2016 sample. 2 Discharged Wastewater Characteristics are the average of three analyses completed on 1/20/2017, 2/14/2017, and4/12/ Fats, Oils, and Grease Fats Oils and Grease (FOG) are defined as organic, polar compounds derived from plant or animal sources that are composed of long chain triglycerides. FOG in municipal wastewater principally consists of cooking oil by-products, and can be broken into two major categories: Yellow grease: Inedible and unadulterated spent FOG formed from Food Service Establishments (FSE). Yellow grease is principally comprised of spent grease that has been utilized for frying foods. Yellow grease is responsive to co-digestion and requires minimal processing before adding to an AD. Brown grease: Floatable FOG, settled solids and associated wastewater retained by grease interceptors and grease traps. In order for brown grease to be suitable for AD, it must first be screened, heated, and blended with other feedstocks. When directly discharged into the collection system, FOG accumulates on pipe walls, which causes reduced conveyance capacity, and increases the potential for sanitary sewer overflows. To avoid these challenges, grease is removed from the discharge with the installation of grease traps (inside, under the sink) or grease interceptors (outside, underground tanks) where FOG is generated. Grease traps and interceptors are gravity separation devices used to retain a conglomeration of suspended grease and food solids referred to grease trap waste (GTW). Restaurant grease trap waste can vary significantly, but in general, contains organic matter in the form of fats, oils, grease, carbohydrates, sugars, and other organic compounds. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

143 Many utilities have implemented ordinances for restaurants and large institutions (e.g., hospitals, schools) to install grease traps to remove grease from kitchen waste streams prior to entering the collection system, and to clean out these traps on a regular basis (e.g. one time per 6 months). Grease trap and grease interceptor wastes are pumped and typically hauled to a WWTP or processing plant for treatment. Grease trap waste contains high BOD, a large fraction of lipids, and a typical energy content of roughly 7,000-10,000 BTUs/pound when dewatered. It has been shown to increase the BTU and percent methane content of digester gas (Long et al., 2012) (Bailey, 2007). While co-digestion of GTW can prove to be a benefit for methane production, it is important to note that challenges exist including the potential for inhibition of methane generation. Table 14 summarizes the typical elements in GTW. Table 14: Characteristics of Grease Trap Waste Parameter Amount Volatile solids content 5.6 % Methane content of digester gas ~14,900 mg/l VSR 70% Total solids content 6.00% Digester gas production 20 cf./lb. VS destruction Source: Feasibility of High Strength Waste Co-Digestion from the San Francisco Public Utilities Commission (Abu-Orf et al, 2014) The quantities of GTW available within the City of Harrisburg is shown in Table 15, as estimated from a URS study (URS 2011). The brown grease fraction of the GTW was calculated first using a per capita generation rate. Then the quantities of GTW were back-calculated from the brown grease quantities. The quantities in Table 14 represent total quantities of GTW, which may not be entirely available for co-digestion at CRW due to existing competition for this material. Characterization factors used in generating this table were also based on the URS study (URS, 2011). Table 15. Estimated GTW generated in the City of Harrisburg Service Area City of Harrisburg Population Served Census 2 Grease trap generation factor of lb./yr.-person, URS Conversion factor of 7.5 lbs./gallon of grease trap, URS % recover factor, URS % brown grease composition factor, URS 2011 Brown Grease Recoverable GTW Production Brown Grease lbs./day 2 gpd 3 gpd 4 gpd 5 49,082 1, ,199 The City of Harrisburg has an ordinance requiring installation of grease traps in restaurants and regular monitoring and clean-out of those grease traps (Chapter ). Additionally, CRW has a limit for discharges of FOG to the collection system and the AWTF of 100 mg/l. FOG discharged to the collection system and at the headworks of the AWTF is difficult to manage and results in high maintenance costs. However, FOG and GTW directed to the digester is largely broken down during digestion, increases gas production, and produces fewer solids than typical August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

144 municipal wastewater solids (Schafer et al., 2007). This potential market will require additional study and revisions to the CRW pretreatment program requirements Slaughterhouse/Meatpacking The meat-processing sector produces process wastewater with high loads of fats, oils, and grease, and solids resulting from the slaughtering of animals and cleaning of the slaughterhouse facilities and meat processing plants. Wastewater comes from the following sources listed in Table 16. Table 16. Major sources of slaughterhouse/meatpacking wastewater Wastewater Source Stage Blood Wash Blood Water Curing Cooking Slaughter X X Blood Processing X Viscera Handling X Hide Processing X X Cutting X Meat Preparation X X Rendering X In general, pretreatment is required to remove the solids from the liquid due to the high grease / solids content of these waste streams. This may be a clarifier, DAF thickener, or a hydrosieve screen. Based on the characteristics of slaughterhouse waste, these wastes are potential candidates for codigestion due to high volatile solids and fat content (Table 17). While the COD of this waste stream is very high, the BOD may only be a fraction of the COD when wood shavings and other similar materials from the production process are present. Table 17. Meat Processing Typical Wastewater Characteristics 1 Parameter Concentration COD 961,000 mg/l Percent Total Solids 8.2 % Volatile Solids 80.9% Typically, fat is collected by a rendering facility, which is a facility that process animal by-products to produce tallow, grease, and high-protein meat and bone meal (US EPA). Bones and blood are commonly used to produce animal feed. Some waste streams may also be land applied as an agricultural fertilizer. As with other food processing sectors, most facilities reuse as much of the by-products as possible, because paying for the disposal of any of these animal byproducts will result in loss of revenue and added costs for management. MM identified seven meatpacking or 1 Source: DAF solids from a Pennsylvania meat processor (September 2015) August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

145 rendering facilities within 50 miles of the CRW AWTF. A summary of the meatpacking facilities is found in Table 18. Table 18. Meatpacking facilities within 50 miles of CRW AWTF Company Location Recommendation Vantage Foods Camp Hill Potential; Contact again Brother and Sister Food Services Harrisburg Potential; Contact again Kessler Foods Lemoyne Potential; Contact again SME Foods York Potential; Contact again Empire Poultry Mifflintown Potential for DAF; Contact again Keystone Protein Fredericksburg Existing Hauled Waste Customer (emergencies only); Has own treatment facility Farmers Pride, Inc. Fredericksburg Has own treatment facility Empire Poultry is a chicken processing facility located in Mifflintown, Pa that has an industrial wastewater treatment facility with direct discharge. The solids (food-processing waste) is land applied; however, DAF solids are hauled off-site and treated at Valley Proteins. Empire Poultry contacted Material Matters in late 2016 to identify cost effective options for handling their DAF solids. Information provided by Empire indicated production of 20,000 gpd of DAF solids, or 4.2 Mgal /yr. We estimated a tipping fee of $0.031 per gallon or less to make co-digestion at CRW attractive for Empire. Keystone Protein is listed as an existing hauled waste customer at up to a maximum of 12,000 gpd. Keystone renders waste from Farmers Pride, Inc., which it makes into pet foods. MM interviewed Nelson Weaver of Keystone Protein, and he indicated that Keystone has a contract with CRW for emergency situations only, with hauling to CRW by Kline s. Keystone has its own wastewater treatment facility and discharges wastewater to a local stream as per their NPDES permit allows. They are planning plant upgrades in 2018 that may require them to transfer a portion of their waste to CRW. They also produce dewatered solids that are land applied by a local farmer Snack Foods Snack food process wastewater is generated during production of a variety of food products including potato chips and related potato snacks, pretzels, cheese curls and puffs, corn chips and related corn snacks, and popcorn. The HSW generated from snack processing facilities includes wash water (from raw product and processing areas), peelings (from potatoes), and spent oil. Facilities with on-site processing typically have high-energy solids from DAF thickening processes. DAF solids such as the solids accepted from UTZ Quality Foods are an effective COD source if fed slowly into an anaerobic digester. Typical characteristics from the UTZ DAF solids are found in Table 19. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

146 Table 19. Wastewater characteristics of UTZ DAF solids 2 Parameter Concentration Hexane Extractable Oil and Grease 309,000 mg/kg BOD5 20,100 mg/l COD 77,800 mg/l TVS% 82% As with many other food categories, snack food processing waste is typically used in agriculture as animal feed or as a soil amendment. However, as is noted in section (Dairy), many manufacturing facilities sometimes seek alternative outlets during winter months when the ground is frozen or snow-covered, including on-farm digesters, constructing new on-farm storage tanks, and treatment at WWTPs. Eight snack-processing facilities were identified within approximately 50 miles of the CRW AWTF (Table 20). Table 20. Snack-processing facilities within 50 miles of CRW AWTF. Company Location Recommendation Dieffenbach's Potato Chips Womelsdorf Follow-up Middleswarth Potato Chips Middleburg Follow-up Herr's Potato Chips Nottingham Follow-up Good's Potato Chips Adamstown Lard is only waste; not viable Martin's Potato Chips Lancaster Follow-up Snyders-Lance (Hanover Manufacturing) Hanover Follow-up Hartley's Chips Lewistown Low cost land app; not viable Utz Hanover Currently utilized 2 Source: Utz Quality Foods analytical Data (June 2016 and January 2017) August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

147 5.0 Findings and Recommendations 5.1 Findings Capital Region Water s Harrisburg AWTF has a robust hauled waste program (602,910 gal/month or approx. 20,000 gpd), with frequent regular monitoring for pollutants/ BOD/ COD. However, it appears that there is capacity in the hauled waste program to include HSW for co-digestion. MM conducted a market survey to determine the availability and characteristics of HSW that are valuable for co-digestion at CRW s Harrisburg AWTF. The identified categories of HSW were based on suitability for co-digestion and location of sources relative to CRW AWTF. MM contacted potential sources of HSW within 50 miles of the CRW AWTF. Major competitors for municipal hauled waste and high strength wastewater were also identified. Results of the market survey provided information relative to the number of generators and characteristics of HSW, current practices of the generators, typical transportation distances, and expected pricing ranges for transportation and tipping. Market considerations for development of a CRW co-digestion program were developed Digester Capacity Capital Region Water currently has two anaerobic digesters, each with a volume of 1.83 MG and a design loading of 30,500 lbs. VSS/day at 5% TS. Of this total capacity, CRW is currently operating one anaerobic digester. This digester is currently loaded at an annual average daily rate of 27,500 lbs. VSS / day at 3% TS, and a maximum monthly loading rate of 36,560 lbs. VSS/day at 5% TS. With both digesters in full operation, approximately 20,000 to 30,000 lbs. VSS/day or 33 to 49% of the total capacity (i.e. 61,000 lbs. VSS/day) would remain available for co-digestion of HSW materials from outside sources Promising Feedstocks Grease Trap Waste from Area Restaurants A study by Schauer and Garbely in 2016 compared two digesters at an Oregon wastewater treatment plant. One digester was co-digested with FOG/GTW, while the other was co-digested with food waste. While both digesters saw increases in biogas production compared to wastewater solids only, the digester with FOG showed a much higher rate of biogas production than the digester with food waste. Grease trap waste (GTW) appears to be a good source for co-digestion. CRW currently does not accept GTW, but as shown in Table 15, the expected volume of available GTW within the CRW service area is estimated at 1,199 gal/day DAF Solids / FOG from dairies, snack food processors / candy processors Dissolved air flotation processes are designed to clarify wastewaters to remove oil and grease. These units are used in a variety of industrial applications, including food processing. UTZ is a snack food producer that discharges to a municipal collection system, and is required to meet pretreatment requirements for FOG and pays a surcharge based on conventional pollutants. When August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

148 land application is not possible, their DAF waste is hauled up to 150 miles for processing. The DAF solids generated at UTZ are a good source of HSW for co-digestion. MM conducted interviews with several food processors in the greater Harrisburg area that produce DAF waste, which could be potential options for CRW. In addition, we understand from waste haulers that other unidentified sources are available Potential volumes and biogas production It has been demonstrated that the addition of HSW (specifically FOG) can provide a significant increase in the biogas production from anaerobic digestion. A review of three studies (Long et al., 2012) demonstrated that adding grease trap waste to digesters in ranges from 10% to 30% by volume yielded biogas production increases of 30-80% respectively. Other studies have demonstrated biogas production increases of % using lab, pilot and full-scale co-digestion studies, using feed rates of up to ~ 50% FOG (Long 2012, Schauer and Garbely, 2016). References Location Reactor Loading Rate Response Bailey (2007) Riverside, CA % GTW by volume Cockrell (2007) Watsonville, CA Average 143,000 gallons GTW/month Vancouver, British Muller et al. (2010) Columbia 9.5% GTW by volume 81.9% Digester gas increase, 9.5% BTU increase, 5 6% increase in methane content >50% Digester gas increase 32.4% Digester gas increase MM contacted approximately 100 potential HSW generators to determine whether their wastes could be valuable waste streams for co-digestion at CRW s ATWF. Of the potential sources, five were identified as promising sources within the 50-mile survey radius. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

149 Table 21. VSS Loadings from selected HSW generators FOG Source Daily Volume (MGD) % Solids TVS % VSS (lbs. day) Utz Quality Foods (2) % 80% 7,126 Empire Poultry (2) % 80% 6,672 Hershey Creamery (2) % 98% 5,848 Grease Trap Waste (1) % 80% 480 Warrell (2) % 80% 110 Total volume per day (gallons) 36,530 Weighted average % solids 7.9% Volume lbs. of VSS per day 20,236 (1) Data from tables 14 and 15 (2) Daily volume provided by generator; % solids and TVS% estimated Table 22. Ratio of HSW to Solids at Selected Loadings Loading Rate AWTF Solids Loading (lbs. VS/day) HSW Solids Loading (lbs. VS/day) Total Solids Loading (lbs. VS/day) % HSW to solids feed Current Average 21,300 20,240 41,540 49% AWTF Design Max. Month 36,560 20,240 56,800 36% (37.7 MGD) Digester Capacity 36,560 24,440 61,000 40% These five sources represent substantial volatile solids loadings that when co-digested represent 25% of the total VSS loading of the two anaerobic digesters at design flow. At the current loading, these sources more than double the current VSS loading (Table 22). Providing a fraction of FOG to an anaerobic digester can provide a significant increase in biogas production. Accepting only the UTZ or Empire Poultry feedstock provides approximately 25% of the feed rate to the digesters at current VSS loadings, which could correspond to an increase of 50-80% in biogas volumes, based on the available data Operational limitations Acceptance of HSW and subsequent co-digestion generates additional biogas, generating more electricity and heat onsite, with the potential to decrease operating costs. Increases in revenues in the form of additional tipping fees are likely. However, operational challenges have been reported. If the HSW is not mixed and fed to the digester carefully, long chain fatty acids (LCFA) can cause toxicity to methanogens and other bacterial groups in a digester. Large increases in loading are also known to cause foaming events in digesters (Schauer and Garbely, 2016), similar to August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

150 challenges seen when feeding large amounts of UTZ DAF solids at CRW in early Many of these challenges can be overcomes by careful mixing, flow, and loading design (Cockrell, 2007). 5.2 Recommendations MM provides the following recommendations for establishing and sustaining a resilient codigestion program, if CRW determines the program benefits and costs meet their operating goals Establish infrastructure for receiving hauled waste The infrastructure for direct feed into the digesters and equalized flow does not currently exist at the AWTF. In order to provide flexibility in receiving hauled waste and allow gradual feeding of hauled waste into the digester, a receiving facility or equalization basin with a pumping system at CRW will enable a more successful co-digestion program. The development of a hauled waste receiving station and basins to allow for slow-feed of the hauled waste into the digester are critical for maintaining control of the digestion system and consistent production of biogas. Adding large quantities of hauled waste directly to the digester can overwhelm the microbial population and lead to foaming or loss of microbes. With the ability to gradually feed waste over a longer period of time, any operational challenges with the digester can be detected and addressed. While building a receiving station would be a significant expense, the increased income from accepting additional hauled waste and the increased biogas production have the potential to be economically viable. MM recommends CRW further investigate the economic viability of building and maintaining a receiving station and equalization system Utilize grease trap waste ordinance Grease trap waste appears to be a reasonable opportunity as a preferred source for co-digestion. CRW does not currently accept grease trap waste. As mentioned previously, GTW is capable of improving biogas production. CRW does not currently take GTW as a hauled waste due to the potential for clogged pipes / pumps and damage to equipment. By discharging GTW into the digester rather than the headworks, collection system maintenance costs can be avoided. Hauled waste pricing for GTW must reflect these avoided costs at the headworks and potential additional biogas production. The City of Harrisburg has an ordinance requiring installation of grease traps in restaurants and regular monitoring and clean-out of those grease traps (Chapter ). Area restaurants likely use waste haulers to periodically clean out their grease traps and remove the waste to another facility. Restaurants should be contacted to determine which hauling/clean-out companies are used, and hauling companies contacted to determine competitive rates for them to bring GTW to CRW. It is also recommended that CRW become more involved in the enforcement of the grease trap ordinance by required submittal of receipts showing that grease traps are being cleaned out on a regular basis. The frequency of required cleanout would depend on the volume of grease produced by the food service establishment and the capacity of their grease traps Follow up with identified facilities and haulers While MM interviewed a number of food processing facility representatives in the greater Harrisburg area, we were unable to connect with a majority. Many of these facilities have potential, and additional effort will be needed to determine the availability and quantity of high strength waste available. Facilities MM contacted were very interested in learning more about when CRW August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

151 will consider co-digestion as an option for their waste management programs. These facilities should be contacted with updates as to the progress of the co-digestion program and expanding CRW s digesters to full capacity. Specifically, Hershey Creamery was interested in understanding how they can utilize CRW s anaerobic digesters in their program. Several facilities producing DAF solids were identified in Southcentral Pennsylvania. These facilities should be notified prior to the expansion of CRW digester capabilities (Hershey Creameries, Harrisburg Dairies, Warrell Corporation, other candy and dairy manufacturers in the area). All potential facilities are listed in Appendix 1. In addition, any local waste haulers should be notified 6 months prior to developing and implementing a co-digestion program to capture seasonal and other HSW from haulers. In particular, JG Environmental expressed interest in collaborating with CRW to bring high BOD waste to the CRW digesters Develop experimental introduction plan When introducing new HSW sources into the digester, the impact to operations should be considered. With a receiving station, HSW can be added gradually to ensure microbes have time to acclimate to the new food source and optimize biogas production. In early February 2017 and ending in May 2017, CRW experienced foaming when adding UTZ DAF solids directly to the thickener for co-digestion. No other HSW is currently added directly to the thickener for codigestion. Monthly volumes of material varied, but peaked at 120,000 gallons in the month of March. This represents a significant portion of the total digester volume. After experiencing foaming problems with the digester, CRW phased out the addition of UTZ DAF solids. The experience with UTZ confirms the importance of gradually adding materials to the digester, monitoring digestion parameters frequently, and establishing an experimental design to determine the optimum amount of certain waste products in the co-digestion system. DAF solids are an excellent feedstock for the production of biogas. In Figure 1 of this report, biogas production showed an increase from January through April of 2017, indicating that the UTZ material contributed to higher biogas production during that period. Before CRW considers resuming UTZ DAF feed into the digester (which is strongly encouraged), the impact of lower volumes, additional monitoring, and gradual loading should be assessed. A similar experimental plan is recommended for all future HSW sources added directly to the thickener or to the digester Pricing Strategies Capturing HSW for co-digestion at CRW will require reasonable transportation costs and attractive tipping fee structure. Hauled waste is a very competitive market with generators looking for the lowest cost option, and haulers developing low cost options to gain the business. Transportation fees are dependent on distance from the AWTP, and are out of the control of CRW. As noted herein, a 50-mile travel distance will result in a transportation fee of $0.03 to $0.05 per gallon. Discussions with haulers indicated that disposal fees not exceeding $0.06 per gallon would encourage interest. Most municipalities base prices based on competition for haulers, despite the fact that this pricing strategy does not fully consider the capital and O&M costs for pretreatment and other plant processes necessary treat the waste. A cost / benefit analysis to establish reasonable tipping fees must also include both the capital costs associated with a receiving station or equalization basin and the economic value of the additional biogas production. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

152 Pricing strategies for hauled GTW, assuming it is added to the digesters, should reflect the cost avoidance for removing it from wet end processes, the capital and O&M costs for pretreatment facilities, and value of the energy generated during co-digestion. However, competitive pricing for grease trap waste must also be considered. Of the 11 municipalities with hauled waste programs Southcentral PA, three accept grease trap waste with fees ranging from $0.102 to $0.11 per gallon. CRW s current pricing strategy is based on solids percentage. During the first month of hauling, wastewater generators are charged a discharge fee based on percent total solids (%TS) at $0.009/every 0.5% TS; the minimum fee is $0.027/gallon and 1,000 gallons. For months two through twelve of the contract, discharge fees are charged per truckload. MM recommends considering a separate pricing strategy for HSW that will be discharge to the digester (or thickener) as opposed to the headworks. Rather than basing prices on % TS, pricing should reflect the value of gas production of the material (%VS, BOD, COD). Dividing the pricing strategies into different categories allows CRW to offer competitive rates for materials that will work well with codigestion Revisions needed to update the hauled waste program Tables 3 and 4 of this report detail the CRW pollutant limits and general parameter limits for hauled waste acceptance at the headworks of the plant. Material Matters recommends developing a second set of criteria for HSW that will be accepted directly into the thickener or the digester. For example, FOG and GTW are a very good source of HSW for co-digestion in the CRW service area, but current requirements would not permit any material with O&G over 100 mg/l. We recommend revising these numbers to allow FOG and GTW to be accepted into the thicker and digester. Characteristics of potential HSW sources should be considered when updating these requirements. August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

153 References Abu-Orf, M., et al. "Feasibility of High Strength Waste Co-Digestion for the San Francisco Public Utilities Commission." Proceedings of the Water Environment Federation (2014): Bailey, Regan S. "Anaerobic digestion of restaurant grease wastewater to improve methane gas production and electrical power generation potential." Proceedings of the Water Environment Federation (2007): Cockrell, Paul. "Grease digestion to increase digester gas production 4 years of operation." Proceedings of the Water Environment Federation (2007): Long, H.; Aziz, T.; de los Reyes III, F.; Ducosted, J Anaerobic co-digestion of fat, oil, and grease (FOG): A review of gas production and process limitations. Process Safety and Environmental Protection. 90: Muller, Christopher, et al. "Co-digestion at Annacis Island WWTP: Metro Vancouver's path to renewable energy and greenhouse gas emissions reductions." Proceedings of the Water Environment Federation (2010): Schafer, Perry, et al. "Grease Processing for Renewable Energy, Profit, Sustainability, and Environmental Enhancement." Proceedings of the Water Environment Federation (2007): Schauer, P. and Garbely, D A FOGgy Day in Oregon. Proceedings of the Water Environment Federation, WEFTEC 2016: Session 309 Co-Digestion, pp (9). URS. 2011, Implement Public Relations and Extend Project Findings of a FOG to Biodiesel Refinery at a Municipal Wastewater Treatment Plant. August USEPA Food Waste to Energy: How Six Water Resource Recovery Facilities are Boosting Biogas Production and the Bottom Line. EPA 600/R-14/240. Veltman, S.; Schoenbert, T.; & Switzenbaum, M.S Acid and alcohol formation during propylene glycol degradation under anaerobic methanogenic conditions. Biodegradation. 9(2): Zitomer, D., Ferguson, N., McGrady, K., & Schilling, J Anaerobic Co-Digestion of Aircraft Deicing Fluid and Municipal Wastewater Sludge. Water Environment Research, 73(6), August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

154 Appendix 1. Identified HSW Dischargers Material Matters identified eleven (11) different categories of HSW dischargers in the greater Harrisburg region. Potential HSW sources were contacted and interviews were conducted with available contacts at the facilities. Company Name Airports Fort Indiantown Gap Airport (Army) Harrisburg International Airport Animal Feed Manufacturers Purina Food Mill Zeigler Brothers Dawn Food Products, LLC Pellman Foods, Inc. Specialty Bakers Bimbo Bakeries Terranetti's Italian Bakery Bakeries Breweries Appalachian Brewing Company Bube's Brewery Ever Grain Brewery Gunpowder Falls Brewing Highway Manor Brewing Howling Henry's Brewery Iron Hill Brewery JoBoy's Brew Pub Lancaster Brewing Company Liquid Hero Brewery Market Cross Pub Molly Pitcher Brewing Company Moo Duck Brewery Mudhook Brewing Co. Old Forge Brewing Company Pig Iron Brewing Company Pizza Boy Brewery/Al's of Hampden Rusty Rail Brewing Company Selin's Grove Brewing Company Snitz Creek Brewery Something Wicked Brewing Company South County Brewing Co. Breweries (continued) City Fort Indiantown Gap Middletown Mechanicsburg Gardners York New Holland Marysville, also in Lititz Carlisle Mechanicsburg Harrisburg Mount Joy Camp Hill New Freedom Camp Hill Hummelstown Lancaster Lititz Lancaster York Carlisle Carlisle Elizabethtown York Danville Marietta East Pennsboro Twp. Mifflinburg Selinsgrove Lebanon Hanover Fawn Grove August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

155 Spring Gate Brewery Spring House Brewing Company St. Boniface Craft Brewing Co. Stoudt's Brewing Company Swashbuckler Brewing Co. The Millworks The Vineyard and Brewery at Hershey Troegs Wacker Brewing Company Wyndridge Farm Zeroday Brewing Company Candy Manufacturing Blommer Chocolate Co Cargill Cocoa and Chocolate Fitzkee's Candies Gardners Candies Hershey Foods L&S Sweeteners Mars Chocolate RM Palmer Co. Warrell Corporation Wolfgang Candy Company Y&S Candies Food Canning Operations Hanover Foods Knouse Foods Co-Operative Inc Toigo Orchards Dairy Processing Clover Farms Dairy Cumberland Valley Creamery Dairiconcepts Dairy Farmers of America Harrisburg Dairy Hershey Creamery Company Kreider Dairy Land O' Lakes Rutters Schreiber Foods, Inc. Swiss Premium Turkey Hill Harrisburg Lancaster Ephrata Adamstown Manheim Harrisburg Middletown Hershey Lancaster Dallastown Harrisburg East Greenville Mount Joy York Tyrone Hershey Leola Elizabethtown Reading Camp Hill York Lancaster Hanover Peach Glen Shippensburg Reading Mechanicsburg Hummelstown Mechanicsburg Harrisburg Harrisburg manheim Carlisle York Shippensburg Lebanon Conestoga Distilleries August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

156 Big Spring Spirits Hidden Still Spirits Manatawny Still Works Mason Dixon Distillery Old Republic Distillery Shawneetown Distillery Spirits of Gettysburg/Battlefield Brew Works Tattered Flag Brewery and Still Works Thistle Finch Distilling Food Production Facilities Advanced Food Products, llc ASK Foods Dutch Valley Food Development, Inc Lancaster Fine Foods Philadelphia Macaroni Company Winter Gardens Quality Foods, Inc Slaughterhouse/Meatpacking Brother and Sister Food Services Empire Poultry Kessler Foods SME Foods Keystone Protein Farmers Pride, INC. Vantage Foods Fresh Vegetable Packaging Fresh Express Snack Food Processing Dieffenbach's Potato Chips Good's Potato Chips Hartley's Chips Herr's Potato Chips Martin's Potato Chips Middleswarth Potato Chips Snyders-Lance (Hanover Manufacturing) Bellefonte Lebanon Pottstown Gettysburg York New Cumberland Gettysburg Middletown Lancaster New Holland Palmyra Myerstown Lancaster Harrisburg New Oxford Harrisburg Mifflintown Lemoyne York Fredericksburg Fredericksburg Camp Hill Harrisburg Womelsdorf Adamstown Lewistown Nottingham Lancaster Middleburg Hanover August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

157 Appendix 2. Survey Approach The following questions were used in interviewing potential HSW producers. Initial contact was made by phone, and subsequent interviewing was completed via Facility Background Information: a. Facility Information: i. Name ii. Address iii. Product(s) produced iv. Plant Size (no. of employees/volume of product produced) b. Contact Information: i. Name ii. Position iii. Phone number iv. address c. Does your company have a corporate environmental officer? Does each facility have a facility environmental officer? Who makes decisions about managing byproducts from each facility? i. Name ii. Phone number iii. address d. Are you familiar with co-digestion of municipal wastewater solids with other commercial and industrial by-products to generate biogas? e. What industry organizations and/or associations does your facility participate in? 2. Waste streams Generated a. What types of wastewater generated: i. Cleaning Activities / CIP ii. Out-of-Spec Product iii. Treatment side streams (i.e., DAF) iv. High strength waste streams (i.e., concentrated by-products) v. Solids (3% to 15% TS) vi. Raw Products vii. Other b. Timing of waste stream generation (throughout typical shift) c. Volume of each type of wastewater is generated: i. Daily ii. Weekly iii. Monthly iv. Annually August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

158 d. Are there seasonal variations in production? i. Explain e. What are the characteristics for each waste stream (if known or available): i. BOD5 ii. COD iii. TSS iv. TVS v. TS vi. Non-Petroleum O&G vii. ph viii. Brix 3. Current Handling Practices a. Discharge to Local Sewer System i. Pretreatment (Yes or No): 1. What is treatment process 2. What age/condition is the pretreatment facility 3. What are discharge limits? Surcharge range? a. Any upcoming new limits? 4. What are high strength wastewater surcharge rates 5. Other hauled out residuals? b. Direct Discharge to Receiving Waters i. What is treatment process ii. What age/condition is the treatment facility iii. What are discharge limits? 1. Any upcoming new limits? iv. Other hauled out residuals? c. Hauled Out i. Characteristics and volumes ii. Hauler name iii. Receiving Facility iv. Hauling fee 1. Mileage portion 2. Non-mileage portion (overhead) 3. Tipping fee portion v. Who makes decision on where hauled waste goes? (hauler or generator) d. Who makes decisions about residual waste treatment and/or final disposition? i. Plant manager ii. Corporate personnel e. What factors are considered when determining how by-products will be managed? (Rate 1 to 5, 5 is big factor) i. Costs ii. Reliability August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

159 iii. Environmental impact iv. Other f. What price point would you go from current provider to Harrisburg? 4. Current End Use and/or Disposal Practices a. What is the final disposition of each waste stream? i. Municipal WWTP or centralized waste treatment facility ii. Landfill iii. Beneficial Use 1. Type? 2. Price? b. What is the biggest challenge you face with the current waste treatment system and/or disposition method? i. Cost capital and/or O&M ii. Reliability iii. Operation 5. Who decides where to go with waste? Hauler or industrial facility? August Material Matters, Inc. TM05 - WRA_CRW_Co-digestion Market Assessment.docx

160 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water TM-6 Dewatering Appendices 77 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

161 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 6 SUBJECT: Prepared by: Reviewed by: Dewatering D. Nixson M. Olivier, J. Emerson Distribution: Date: June 21, 2017 Revised on: August 11, 2017 CONTENTS I. INTRODUCTION II. III. IV. EXISTING BELT FILTER PRESS PROCESS IMPROVEMENTS FUTURE DEWATERING REQUIREMENTS V. ALTERNATIVES FOR FUTURE DEWATERING VI. SUMMARY ATTACHMENTS: 1.) N/A REFERENCE DRAWINGS: 1.) N/A August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

162 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 I. INTRODUCTION See Technical Memorandum No. 1 for a description of the Harrisburg AWTF and the overall biosolids process. Technical Memorandum No. 6 provides summary design information regarding the dewatering of digested biosolids at the AWTF. Digested sludge flows by gravity through two separate pipelines with in-line sludge grinders, and then is pumped to belt filter press with hose pumps. Polymer is added through a ring injector, which is upstream of a mixing valve. The sludge is then fed to the gravity section of the belt filter presses. The two (2) in-line sludge grinders break down larger solids, and replace the function of the inline grinder pumps in the digested sludge pumping station. Discharges from the three (3) belt filter press hose pumps can be directed to either of the two (2) 2.5 meter wide belt filter presses. The polymers used in the dewatering process are received as a powdered solid, delivered in supersaks. The polymer supersak is placed on a skid, from which polymer is metered by a screw conveyor into a pneumatic line that pushes it into a 3,300 gallon fiberglass polymer mix tank. Water is added to the polymer and the contents are mixed. Once the polymer is conditioned, it is pumped by two (2) progressing cavity pumps to a storage/feed tank, also a 3,300 gallon fiberglass tank. The polymer solution is then pumped into an injection ring located on each feed pump pipeline which feeds the conditioned sludge to each belt filter press. During the dewatering process, following discharge of the dewatered cake, the press belts are washed with spray water. A wash water skid equipped with three (3) booster pumps provides the pressure to adequately wash the belts. The cake is discharged from the belt filter press onto a ribbed belt conveyor which conveys the cake into a dump truck which transports it to a covered storage area. Table 6-1 summarizes the process criteria for the existing belt filter presses. Dewatered cake produced by the belt filter presses has averaged more than 21% solids for the past three years, but the performance has been inconsistent. The monthly average cake solids was below 20% for 7 months in 2016, and for all of the first 6 months of The dewatered cake cannot be stored for more than 10 days at the land application sites if it is less than 20% solids. When the covered storage area is full, the biosolids are disposed of at a landfill. As an extension of the Biosolids Facilities Improvement Plan, a study of the dewatering of biosolids and the belt filter press operation is being pursued. The study will be included as an appendix in the Final Facilities Improvement Plan. II. Existing Belt Filter Presses Belt Filter Press Condition The existing belt filter presses were installed in 2011 and are in good physical and operating condition. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

163 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 The ancillary equipment for the belt filter presses includes: Polymer handling equipment Polymer make down tanks and storage tanks Digested sludge in-line grinders BFP wash water booster pumps BFP feed pumps. The ancillary equipment is also in good physical and operating condition. Belt Filter Press Capacity The design criteria for the existing belt filter presses is presented in Table 6-1. Table 6-1. Existing Belt Filter Press Design Criteria Units 2, in parallel Manufacturer Ashbrook Simon-Hartley Type Dual belt Effective Belt Width 2.5 meters Solids Loading Rate 2,000 lbs dry solids/hr, each 4,000 lbs dry solids/hr, total Feed Solids Content 2-6% Runtime, both in operation Capacity 16 hours a day, 7 days a week 32,000 lbs dry solids/day each 64,000 lbs dry solids/day total Information on the digested sludge at the facilities improvement plan digester capacity at a plant flow of 37.7 MGD, and the resulting belt filter press capacity are in Table 6-2. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

164 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 Table 6-2. Belt Filter Press Estimated Required Plant Design Flow (37.7 MGD) Digested Sludge at Digester Capacity 52,000 lbs TSS/day Digested Sludge Volume at Digester Capacity 150, ,000 gallons per day Digested Sludge, Percent Solids % Solids Loading Rate Volumetric Loading Rate Runtime, both in operation 2,000 lbs dry solids/hr, each 4,000 lbs dry solids/hr, total gpm, each gpm, total 13 hours a day, 7 days a week 1 With separate WAS and primary sludge thickening to 5-6 % solids and average hauled waste 5-6% solids Based on Table 6-2, the two existing belt filter presses have sufficient capacity to dewater the future quantity of sludge projected by the facilities improvement plan. Each belt filter press would be operated more than 12 hours a day, 7 days a week, which does not allow for redundancy in the dewatering system when approaching the quantity of solids projected by the facilities improvement plan. Therefore, if one belt filter press were to be taken offline for more than 2-3 days, a rental dewatering unit would be needed to dewater the projected sludge quantity. The belt filter presses and the ancillary equipment have sufficient capacity, and are expected to provide reliable service for their intended purpose for at least the next ten years. III. Process Improvements As mentioned above, the AWTF has intermittently produced dewatered biosolids at less than 20% cake solids which limits the dewatered biosolids storage options. There are many factors that influence dewatering of biosolids, and contribute to the cake solids produced. Of these factors, some are within the control of the AWTF, and others are not. Some factors cannot be significantly improved until the addition of new processes and/or rehabilitation of existing facilities are complete. Those within the control of the AWTF include the following: 1.) Polymer conditioning 2.) Digested sludge degree of stabilization 3.) Digested sludge characteristics 4.) Belt filter press condition and operation August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

165 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 The dewatering study portion of the Facilities Improvement Plan will review the existing belt filter press operation. The goal of the study is to make recommendations to modify operation of the belt filter presses, and possibly other aspects of the AWTF, to reliably maintain cake solids greater than 20%. The study will also consider the effects the anticipated hauled waste will have on the dewaterability of the digested solids. Polymer Conditioning The dewatering study will include an evaluation of the chemical conditioning (i.e. polymer addition) of the sludge. Technical support from the current polymer supplier will be engaged to evaluate polymer make down procedures, polymer dosing rates, location of the polymer injection point and alternate polymers to determine what improvements could be made. Digested Sludge Degree of Stabilization The digestion process is affected by many factors including sludge characteristics and feed rate, mixing, temperature setpoint and variation in temperature, and solids retention time. A greater degree of biosolids digestion generally results in improved dewaterability. The planned digester improvements including mixing, heating, piping and pump replacement will result in improved digestion efficiency. Digested Sludge Characteristics The cake solids will also be positively impacted by maintaining the digester temperature relatively constant at about 98ºF. Current variations in temperature are largely caused by rag buildup in the piping and heat exchanger. The planned influent screening facility will reduce the amount of rags in the sludge. The recommendation to separately thicken primary sludge and WAS to increase the solids concentration of each, will result in a longer solids retention time, improving the degree of digestion. In addition, the digested sludge solids concentration and degree of stabilization will also increase, and in turn positively impact the dewatered cake solids. Belt Filter Press Condition and Operation The belt filter press operation will also be evaluated including an inspection of the condition of the belts, and testing of the belt tension and speeds. A review of the maintenance records of the belt filter presses will identify if any maintenance items are overdue. The feed rate to the belt filter press will also affect the cake solids, with higher feed rates negatively impacting the cake solids. Summary of Belt Filter Press Improvements Some of the belt filter press improvements and adjustments discussed in this section can be August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

166 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 implemented more rapidly than others. In addition, some will have a larger impact on dewatering cake solids than others. The polymer investigation and adjustment could be one of the first steps, and may provide a significant benefit. That would allow time for the remainder of the improvements and adjustments above to be implemented and allow the belt filter presses to provide the required cake solids. It is also recognized that depending on timing of the implementation and the actual results of the improvements and in light of possible future dewatering requirements discussed in Section IV, other dewatering technologies may need to be investigated. Sludge Pretreatment In addition to thickening, digester and belt filter press improvements, sludge pretreatment could be investigated as another means of improving dewatered cake solids. Biosolids trap a portion of water within the cells of the microbes, and between the mesh of microbes and inert materials. Pretreatment is intended to release water, either or both, within the cells (primarily WAS) and between particles to improve dewatered cake solids. Although there are many research papers describing methods of pretreatment of biosolids for improved dewatering, including elevated temperature or pressure, ultrasound, and chemical, there are very few full scale applications. The SLG process as manufactured by Orege has an installation in the Lehigh County Authority Pretreatment WWTP in Pennsylvania. In the SLG process compressed air is combined with the sludge in a pressure vessel. When the sludge leaves the pressure vessel through a pressure reducing valve the rapid change in pressure introduces small air bubbles into the sludge which provide a path for the interstitial water to drain out. Pilot testing would be recommended prior to further evaluation of any technologies that are to be considered. IV. Future Dewatering Requirements Local biosolids regulations are likely to become more stringent in the foreseeable future, i.e., 5-10 year timeframe. There may be more reporting requirements, a higher quality of biosolids required for land application, and restrictions on land available for application. While these changes in regulations are developed and finalized, the best course of action is to continue utilizing the existing belt filter presses. As more stringent biosolids disposal regulations become imminent, the production of Class A biosolids should be considered. To achieve Class A quality, the biosolids must undergo one of the Environmental Protection Agency (EPA) approved treatment methods. One of the common methods for producing Class A biosolids involves heat drying the dewatered cake to greater than 90% solids. Even though significant energy (digester gas) will be required, an evaluation including cost savings in disposal, i.e., through beneficial reuse instead of landfilling, and heat recovery, will show benefits in heat drying. The higher the percent solids in the dewatered cake, the less heat energy that must be used to dry August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

167 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 the cake. In fact, the capital and higher operating costs of new dewatering equipment can potentially be fully offset by subsequent fuel savings in the heat drying operation. Class A biosolids must be treated to further reduce pathogen levels beyond the requirements of Class B biosolids. This is one of the reasons they have few restrictions on where they can be land applied. Allowable disposal areas include publically accessible and residential lands. Heat drying also reduces transportation costs. V. Alternatives for Future Dewatering Depending on future regulations, the characteristics and volume of hauled waste, and many other factors, there may be need in the future to consider other dewatering technologies. This section briefly discusses currently available dewatering technologies that claim consistent biosolids cake dewatered to above 20% solids, including: Plate and Frame Filter Centrifuge Screw Press Volute Dewatering Press Rotary Press Other than the centrifuge, pilot testing would be highly recommended to confirm actual average percent solids performance at AWTF. The plate and frame filter is a batch process, is capital intensive, has a large footprint and some plants have experienced operational difficulties. Therefore, it is not included for further consideration. Centrifuge The centrifuge is widely utilized in dewatering biosolids, with high cake solids and high throughput as major advantages over most other technologies. Figure 6-1. Cutaway View of Biosolids Dewatering Centrifuge Credit: Centrisys Compared to the other technologies below, the disadvantages of the centrifuge include: August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

168 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 High energy consumption High capital and maintenance cost Specialized maintenance skills Screw Press and Volute Dewatering Press The screw press and volute dewatering press are similar in overall configuration, with a center conveying screw pushing the solids that are larger than the openings in the dewatering drum towards the discharge end. See Figure 6-2 for a typical screw press, and Figure 6-3 for a volute dewatering press. The screw press uses a static perforated, or slotted drum which separates the solids. The volute press utilizes the annular space between donut shaped plates to separate out the solids. The screw and volute press both have low capital costs and low energy consumption. Both the screw and volute press require sufficient space within the building for the removal of the conveyor screw. The existing belt filter press room is therefore unlikely to be compatible with either technology. The volute dewatering press has relatively few installations in the United States, but has fewer moving parts than the belt filter press or screw press which should translate to lower maintenance costs. Figure 6-2. Screw Press Credit: Schwing Bioset, Inc. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

169 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 Figure 6-3. Volute Dewatering Press Credit: Process Wastewater Technologies, LLC Rotary Press The rotary press utilizes two vertically oriented plates with slotted openings, see Figure 6-4 for a general arrangement of a six channel rotary press. Flocculated biosolids are pumped in between the plates which separates the solids from the filtrate. The slow rotation speed of the plates provides friction to restrict the solids movement and provides compression of the solids cake to control the cake solids. The rotary press has a lower throughput than the screw press or belt filter press and therefore requires more floor space. The room where the existing belt filter presses are located may not be large enough for the required rotary presses, so that aspect would require evaluation. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

170 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 6 Figure 6-4. Six Channel Rotary Press Credit: Fournier Industries V. Summary The existing belt filter presses have adequate capacity for the anticipated sludge production for the planning period considered. They will likely require improvements, as discussed in Section III, to consistently provide the 20% biosolids cake solids required. Depending on the results from the short-term belt filter press operational and polymer modifications discussed above, the piloting of the Orege process would be a suggested next step. The implementation of the thickening improvements and digester improvements discussed in Section III will further improve cake solids. It is therefore recommended to proceed with these improvements, including polymer conditioning modifications, and consider the replacement of the belt filter presses only when future conditions dictate it. When future regulations for higher cake solids, or further restrictions on Class B land application, force the landfilling of Class B biosolids, the overall case for producing Class A biosolids will be strengthened. At that time the move to heat drying the biosolids to generate Class A biosolids would be beneficial. Upgrading of the dewatering process to another technology capable of producing a drier cake to feed the drying process should be considered. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM06 - Dewatering.docx

171 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water TM-7 Biogas Utilization Appendices 78 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

172 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 AWTF BIOSOLIDS FACILITIES IMPROVEMENT PLAN HARRISBURG, PA TASK ORDER NO.: PROJECT NO.: TECHNICAL MEMORANDUM No. 7 SUBJECT: Prepared by: Reviewed by: Biogas Utilization D. Nixson, N. Cohen M. Olivier, J. Emerson Distribution: Date: June 22, 2017 Revised on: August 11, 2017 CONTENTS I. INTRODUCTION II. III. IV. EXISTING BIOGAS SYSTEM BIOGAS PROJECTIONS ALTERNATIVES FOR BIOGAS UTILIZATION V. PRELIMINARY COST ANALYSIS VI. SUMMARY ATTACHMENTS: 1.) N/A REFERENCE DRAWINGS: 1.) N/A August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

173 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 I. Introduction See Technical Memorandum No. 1 for a description of the Harrisburg AWTF and the overall biosolids process. Technical Memorandum No. 7 provides summary design information regarding the utilization of the biogas generated from the anaerobic digestion of biosolids at the AWTF. There are several potential beneficial uses for biogas including the following: A.) B.) C.) D.) E.) Combust the biogas and recover the heat and kinetic energy, e.g., combined or separate heat and power generation Use a fuel cell to generate electricity and heat Off-site use of the biogas, e.g., as natural gas substitute Use as fuel to heat the digesters Use as fuel for heat drying biosolids AWTF is currently utilizing a hybrid heat and power generation, with partial recovery of heat from the engine driven generator, and the use of separate boilers for additional heat generation capacity. By integrating the heat and power generation into a combined heat and power system would improve the overall energy efficiency. In combined heat and power all of the biogas is burned in the engine or turbine driven generator, and the heat for the digesters is supplied by the waste heat generated by the engine. A fuel cell can also be used in the generation of combined heat and power. Another alternative to consider is the use of the biogas off-site, e.g., direct injection into natural gas pipeline, or use in compressed natural gas vehicles. In any beneficial reuse alternative the biogas requires a certain level of pretreatment prior to use. In order of increasing pretreatment requirements is the internal combustion engine, turbine, fuel cell and then off site use. II. Existing Biogas System The digester gas is routed through the pipe tunnels, through the Digested Sludge Pump Station, then compressed in the Gas Compressor Building and stored in a spherical tank. The tank has a pressure relief valve to avoid damage to the tank. Excess gas is burned off at an adjacent ground level flare. Tables 7-1, 7-2, 7-3 and 7-4 summarize gas collection, usage, and storage equipment. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

174 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table 7-1. Existing Low Pressure Gas Compressors Units 2 Manufacturer Spencer Turbine, Co. Size 4 x 4 inches Output Pressure Capacity, each psia 240 cfm Table 7-2. Existing Gas Purifier Units 2 Manufacturer Varec, Inc Type Iron Sponge Treatment Volume 40 cubic feet Capacity 45,000 standard cubic feet per day Pressure Drop 0.5 inches of water column August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

175 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table 7-3. Existing High Pressure Gas Compressors Units 2 Manufacturer Ingersoll-Rand Type Single Stage, Double Acting Discharge Pressure 50 psig Capacity 80 Actual cubic feet per minute Table 7-4. Existing Storage Tank Units 1 Manufacturer Pittsburgh-DesMoines Steel Co. Size 42 feet diameter Pressure, Maximum 50 psig Capacity 38,793 cubic feet Digester gas is burned in two (2) boilers to provide hot water for heating the primary digesters, and space heating buildings. The boilers can also be fired with fuel oil, but there has been sufficient digester gas for many years. Information on the boilers follows. Table 7-5 summarizes the boilers. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

176 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table 7-5. Existing Boilers Units 2 Manufacturer Fuel Biogas consumption Capacity, each Weil-McLain Biogas #2 Fuel Oil 12, inches W.C. 6,391,141 Btu/hr Digester gas is also used to power two (2) internal combustion engine driven electric power generators. The power generated is put onto the utility grid. Prior to combustion, the digester gas is filtered by a condensing filter to remove condensable water vapor from the gas. The engine cooling is performed with roof mounted radiators, with closed loop circulation back to the engine blocks. Table 7-6 summarizes equipment in the cogeneration facility. Table 7-6. Existing Engine Drive Generators Units 2 Manufacturer Waukesha Fuel Biogas Generator Output, each Electric Generated Feed Gas Requirements 400 kw 480 V 3 phase 60 Hz 4 wire 500 BTU/cu ft at 25 psig August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

177 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 III. Biogas Projections Summary information on the existing digester performance and resulting biogas generation is provided in Table 7-7. Table 7-7. Existing Gas Generation 1 TSS in Digester Feed VS in Digester Feed VS Destroyed in Digesters VS Destruction / Fed Ratio Digester Gas Produced 38,100 lbs/day 23,700 lbs/day 11,300 lbs/day ,000 cfd Gas Produced 11.9 cf biogas per lb of VS destroyed 1 Average values for May 2016 to June 2017, i.e., after BNR Upgrade Start Up The ratio of gas produced to pounds of volatile solids fed is below that typically found in municipal anaerobic digestion. This is likely due to the operational concerns discussed in Technical Memorandum No. 4 Anaerobic Digester including thickened sludge low solids concentration and its effect on solids retention time, incomplete mixing, and temperature control due to vivianite buildup. Once the currently planned primary digester upgrades are completed, digester performance will improve. Implementing other improvements described in the Biosolids Facilities Improvement Plan will also improve performance and result in more typical biogas production rates. In addition to improving the digester performance, the introduction of carefully selected high strength hauled waste is intended to not only increase the total gas produced, but also to improve biogas generated per pound of volatile solids destroyed in the digester. Regardless, the Facilities Improvement Plan will utilize a conservative biogas production rate more typical of a well operating anaerobic digester. Summary information on the anaerobic digester design capacity and resulting biogas generation is August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

178 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 provided in Table 7-8. Table 7-8. Projected Gas Generation at Facilities Plan Digester Capacity TSS in Digester 76,900 lbs/day Feed VS in Digester 61,000 lbs/day Feed VS Fed/ Destruction 0.50 Ratio VS Destroyed in 30,500 lbs/day Digesters Gas Produced 13.0 cf biogas per lb of VS destroyed Digester Gas Produced 397,000 cfd IV. Alternatives For Biogas Utilization Biogas is a product from anaerobic digestion that has traditionally been under-utilized. One method for improving the energy recovered from biogas is to use it as a fuel source utilizing a combined heat and power (CHP) technology. CHP systems convert the biogas into electricity and recover the heat generated in the process. The heat can then be used to maintain optimal digester temperatures and/or space heating buildings. Although other technologies exist, two promising CHP technologies that will be evaluated for the AWTF, are fuel cells and reciprocating engine driven generators. Fuel Cells Of the two, fuel cells are newer and less prevalent. Fuel cells use an electrochemical process to convert hydrogen from hydrocarbons, such as methane, into electricity. As of 2015, there are 126 fuel cells in the United States, with a combined capacity of 67 MW. The average installed fuel cell has a capacity of 532 kw. The thermal energy from the fuel cells can be recovered and used for heating demands. The fuel cell is made up of three primary structures: fuel cell stack, fuel processor, and power conditioner. The cell stack generates the direct current electricity which is then used in the fuel processor to convert the fuel into a hydrogen-rich feed stream and finally the power conditioner August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

179 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 processes the direct current electric into alternating current. There are several types of fuel cells which have been used for CHP, including phosphoric acid (PAFC), molten carbonate (MCFC), solid oxide (SOFC), and proton exchange membrane (PEMFC). Fuel cells are known for achieving high efficiency levels and generating constant power when supplied an uninterrupted supply of biogas. Fuel cells typically have a power to heat ratio of 1.26, which is advantageous for systems that require more electricity than heat. Another advantage of a fuel cell is the low emissions of carbon dioxide (CO2) and even lower emissions of oxides of nitrogen (NOx). Fuel cells can produce CO2 emissions ranging from 555 to 729 lbs/mwh, whereas a typical natural gas combined cycle power plant will produce lbs/mwh. Besides less air pollution, fuel cells also do not create any noise. Currently fuel cells have a higher capital cost per kwh than internal combustion technologies. A fuel cell can have an installed cost ranging from $4,600 to $10,000/kWh. While fuel cells are fairly reliable, 90-95%, they do require periodic replacement and maintenance of their catalysts and fuel cell stacks. Fuel cells also have slow start times, 3 hours 2 days. Reciprocating Engines Another option that utilizes CHP are reciprocating engines. As of 2015, there are nearly 2,400 reciprocating engine based CHP systems in the United States. Reciprocating engines are available in sizes ranging from 10 kw to 10 MW. There are two designs for reciprocating engines: spark ignition Otto-cycle engines and compression ignition Diesel-cycle engines. The two designs are mechanically the same, but differ on the method of fuel ignition. Spark ignition uses a spark plug to ignite a pre-mixed air fuel mixture and for CHP most reciprocating engines use a 4-stroke spark ignition. Further, reciprocating engines are usually characterized as either rich-burn or lean-burn. Rich-burn engines operate near the stoichiometric air/fuel ratio, thus air and fuel quantities result in complete combustion, with little excess air. Lean-burn engines run at significantly higher levels than the stoichiometric ratio. Reciprocating engines have electric efficiencies that are not as high as fuel cells, ranging from 25-50% (LHV). The installation cost and maintenance cost is lower for reciprocating engines. Reciprocating engines, with proper maintenance, can be available 90-96% of the time, with a 60 second start-up time. Rich-burn reciprocating engines have a power to heat ratio of approximately 0.62 and lean-burn engines have a ratio of 0.86, which compared to the fuel cell s ratio of 1.26, reciprocating engines respectively produce more heat than electricity. One of the most significant differences between the two CHP technologies is the emissions of criteria pollutants. Reciprocating engines emit significant amounts of NOx, carbon monoxide (CO), and volatile organic compounds (VOCs). Biogas Pretreatment Biogas pretreatment is another component that must be analyzed in relation to CHP technologies. Depending on the technology, the biogas has to be treated in order to remove certain elements that can negatively impact the technology s performance. Also pretreating the biogas can increase its August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

180 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 heating value. Biogas from digesters is typically pretreated to remove solid particulates, siloxanes, hydrogen sulfide (H2S), and water vapor. The presence of water in biogas is desirable for combustion devices and fuel cells, by contributing to lower NOx emissions in the former and is used for stream reforming of methane in the latter. However, when H2S and water vapor react they form sulfuric acid, which is very corrosive to engines. Thus for either technology, the biogas can be cooled in a heat exchanger in order to remove water vapor. This is a more important pretreatment step for fuel cells than reciprocating engines. For both CHP technologies, it is essential to remove H2S. The most common hydrogen sulfide removal method is adsorption (i.e., scrubbing) using a hydrated ferric oxide or other catalytic media. A gas analysis would need to be conducted to determine whether a two-stage sulfur removal system is needed. For fuel cells it s important to also remove carbon dioxide (CO2) thus using slaked lime (Ca(OH)2) as an absorption media is ideal as it removes both CO2 and H2S. The term siloxanes refers to a series of volatile organic compounds. When siloxanes oxidize they form silica (SiO2), which can deposit on surfaces, and is particularly dangerous to high temperature fuel cells as it can fill the anode s porous structure. The most common method for siloxane removal is adsorption using active carbon or silica gels. The media can be regenerated through temperature swing adsorption (TSA) or pressure swing adsorption (PSA). The removal of siloxanes should occur downstream of the H2S and water vapor removal methods. In general, reciprocating engines need an H2S pretreatment removal, while fuel cells require full treatment (i.e., removal of water vapor, CO2, and trace elements). Natural Gas Pipeline Injection Another alternative for beneficial use of biogas is injecting it into a utility s natural gas pipeline. However, this process requires an advanced biogas upgrading system and, as seen in Figure 1, selling biogas as a renewable natural gas, is not as valuable when compared to electricity, however, the price is more consistent over time. The capital investment for natural gas pipeline injection can be less than a combined heat and power system. A heat source for the primary digesters would still be required if a CHP process is not utilized. A preliminary cost analysis is presented in Section V to compare these alternatives. Typically the biogas has to undergo treatment to remove contaminants and excessive CO2, an odorant has to be added, and finally be compressed and then sold to a local utility. It can also be used onsite as a vehicle fuel but this is very capital intensive. There is a water-wash technology available through Greenlane biogas that is ideal for grid injection and requires no heat or chemicals. It removes H2S without pretreatment and has reliable compression technology. Essentially it combines all the steps and results in a product that is pipeline acceptable. The company also claims ~99% energy available to pipeline from biogas produced. If the site requires natural gas, this would be a great option, however, selling treated biogas as a natural gas supplement compared to utilizing the biogas to generate electricity does not appear to be economically justified. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

181 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Figure 1: Historical Energy Costs Credit : Hazen 2017 In Figure 1, the potential revenue for biogas treated to natural gas (NG) pipeline quality is shown in light green (lowest on the chart). When natural gas is compressed sufficiently (i.e., 3,600 psi) it is referred to as compressed natural gas which is represented by the dark green line, and abbreviated as CNG. V. Preliminary Cost Analysis Typical municipal values for biogas were used to evaluate the two viable options discussed above, lean burn reciprocating engine driven generator, and fuel cell. The biogas design criteria, the actual current prices for natural gas, and electricity sold to the utility are presented in Table 7-9. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

182 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table 7-9. Biogas Utilization Design Criteria Methane Content Digester Heat Requirement, Winter Biogas Energy Potential 1 Natural Gas, Purchased from Utility Electricity, Sold to Utility 0.65 volume methane/volume biogas degree F temperature rise, plus 10% for heat losses 600 BTU/ cubic foot $5.31 / 1000 cubic feet $0.07/kWh 1 Based on average lower heating value of biogas, Opportunities for Combined Heat and Power at Wastewater Treatment Facilities, October 2011, US EPA There are many established manufacturers of lean burn reciprocating engine driven generators utilized in combined heat and power systems. Most of the equipment manufacturers will team with a combined heat and power system integrator to design the system and supply the ancillary equipment (e.g., pumps, heat exchangers, biogas pretreatment, etc.). Rather than performing an economic analysis based on a single manufacturer, we have utilized typical design parameters as compiled by the US Environmental Protection Agency in their publication entitled Opportunities for Combined Heat and Power at Wastewater Treatment Facilities, October Key design parameters are in Table August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

183 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table CHP Design Information 1 Parameter Electric Efficiency Overall Heat and Power Efficiency Power to Heat Ratio Units BTU Electrical Output / BTU Combusted BTU Recovered/ BTU Combusted BTU Power Output/ BTU Heat Output Lean Burn Reciprocating Engine Driven Fuel Cell Capital Costs 2 $/kw capacity $3,200 $5,500 Maintenance Costs $/kwh Based on averages, Opportunities for Combined Heat and Power at Wastewater Treatment Facilities, October 2011, US EPA 2 Includes pretreatment equipment. Does not include any building or site improvements that may be required. From Table 7-10, it can be seen that the fuel cell has a significantly higher energy conversion efficiency, and higher overall energy recovered efficiency than the lean burn reciprocating engine. The capital costs and maintenance costs for fuel cells are higher than the lean burn reciprocating engine. These differences are discussed further in conjunction with Table 7-12 below. Based on the biogas generation at the facility improvement plan capacity (i.e., digester at full design capacity) and the design information in Table Nos. 7-9 and 7-10, Table 7-11 contains the information regarding the capacity of the CHP system. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

184 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table CHP Capacity Parameter, per day Biogas Energy Potential Units Lean Burn Reciprocating Engine Driven Fuel Cell BTU 238,000, ,000,000 Energy Produced Heat Recovered Heat Deficit, Winter Only kwh 960 1,222 BTU 90,500,000 81,000,000 Recovered minus BTU required by Digester Heat -1,200,000-10,700,000 A simple cost benefit analysis of the two types of CHP system is presented in Table The purpose of this cost benefit analysis is not to determine the actual income AWTF can expect from the CHP, but to compare the two different technologies against one another. The analysis does not consider the time value of money, but instead uses a 20 year straight line depreciation of the installed capital costs. It also assumes biogas generation at full capacity beginning at start-up and 100% utilization of the biogas. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

185 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 Table CHP Cost Benefit Analysis Parameter Unit Nominal Size Units Installed Capital Costs, $ CHP Equipment 1 Installed Capital Costs, $/year CHP Equipment 2 Electric Generated Value of Electric Sold to Utility Maintenance Costs Natural Gas Purchased for Digester Heating 3 Natural Gas Purchased for Digester Heating Net Value of Electricity Generated Lean Burn Reciprocating Engine Driven Fuel Cell kw 1,000 1,400 4,000,000 9,600, , ,000 kwh/day 960 1,222 $/year 629, ,000 $/year 168, ,000 MBTU/year $/year ,200 $/year 260,000 (5,000) 1 Includes a 25% contingency 2 Uses a linear depreciation of capital costs over 20 year life for a per year cost 3 Assumes 90 days a year need supplemental heating beyond what the CHP system generates Based on the net value of the electricity generated in Table 7-12, the fuel cell based CHP is not appropriate for AWTF, and the lean burn reciprocating engine will provide an economic benefit. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

186 Capital Region Water AWTF Biosolids Facilities Improvement Plan Technical Memorandum No. 7 VI. Summary The use of a combined heat and power system will provide higher energy recovery efficiency than the existing separate system. Considering that both the existing boilers, and engine driven generators are beyond their expected life, investing in a combined heat and power system is recommended. The reciprocating engine driven generator is well known to the AWTF operations and is projected to provide an economic benefit to the facility. Therefore it is recommended that the AWTF plan to install a lean burn reciprocating engine based CHP system. The amount of projected biogas is based on typical values for municipal biosolids anaerobic digestion. This implies that the biogas generated from the anticipated hauled wastes will average to similar values to that of the biosolids. In fact, the actual blend of hauled waste may vary significantly over time, as will the ratio of hauled waste solids to biosolids. Therefore, the amount projected biogas will have a large variation over time. Therefore the CHP system should be designed to provide for significant flexibility. Manufacturer s generally carry a nominally sized 500 kw continuous rated 3 phase 60 Hz biogas fueled generator. Considering redundancy and turn down flexibility, three (3) 500 kw units would be recommended. Preliminary sizing based on catalog information would indicate that the three units could fit in the existing cogeneration building. Pretreatment equipment, and some of the heat recovery equipment would be installed adjacent to, or on the roof of the building. The 480V power that is provided by the generator is stepped up to medium voltage prior to connecting to the utility power lines by a transformer. The existing transformer would need to be replaced, as would the cables from the cogeneration building to the utility power lines. August Whitman, Requardt & Associates, LLP N:\ \Engineering\Design\Biosolids Facilities Imp Plan Tech Memos\Final\TM07 - Biogas Utilization.docx

187 Harrisburg Advanced Wastewater Treatment Facility Biosolids Facilities Improvement Plan Capital Region Water Appendix B Net Present Value Spreadsheets Appendices 79 N:\ \Engineering\Reports\Biosolids Facilities Improvement Plan\Final\Capital Region Water Report FINAL.docx

188 AWTF Biosolids Improvement Plan Simple Payback Methods 3/12/2018 Scenario Incremental Capital Annual Benefit 1 Simple Rate of Return Years to Payback Base Case $ 15,470,010 $ 892, % 17 30% HW $ 5,910,100 $ 529, % 11 Without HW $ - $ 276,964 N/A N/A 1 Annual Benefit = First Year Revenue from Electric generated + Offset of purchase of Nat Gas for heating + tipping revenue - HW disposal costs - Maintenance and Operating Costs (2.2% of Incremental Capital) NPV (25 Year Project Life) Scenario Incremental Capital NPV Base Case $ 15,470,010 $ 1,100,000 30% HW $ 5,910,100 $ 6,000,000 Without HW $ - $ 5,500,000 N:\ \Engineering\Cost_Est

189 Summary NPV for Scenarios SCENARIO Decrease Elec. Cost Increase Hauling Cost Increase Gas Cost by 50% by 20% by 15% BASE CASE $ 1,100,000 $ (900,000) $ 3,740,000 $ 6,300,000 $ (900,000) $ 2,900,000 $ (300,000) 30% HAULED WASTE NO HAULED WASTE Baseline Increase Capital by 20% Decrease Capital by 15% Increase Elec. Cost by 15% $ 6,000,000 $ 4,700,000 $ 7,000,000 $ 9,900,000 $ 4,500,000 $ 7,200,000 $ 5,300,000 $ 5,500,000 N/A N/A $ 7,500,000 $ 4,700,000 $ 6,200,000 N/A Scenario Incremental Capital Annual Benefit Simple Rate of Return Years to Payback Base Case 30% HW Increase Capital by 20% Decrease Elec by 20% Increase Elec. By 15% Increase Capital by 20% Decrease Elec. By 20% Increase Elec. By 15% $ 18,564,012 $ 824,098 4% 23 $ 15,470,010 $ 757,956 5% 20 $ 15,470,010 $ 1,227,691 8% 13 $ 7,092,120 $ 503,486 7% 14 $ 5,910,100 $ 447,866 8% 13 $ 5,910,100 $ 733,551 12% 8 N:\ \Engineering\Cost_Est

190 Net Present Value Base Case Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 25,582 24,995 24,402 23,803 23,198 22,587 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (5,910,010) (9,560,000) Electricity Revenue ($) 375, , , , , , , , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , , , , , , , ,124 HW Sludge Hauling Costs 3 (259,447) (253,862) (248,222) (242,525) (236,771) (230,960) (225,091) (219,163) (743,703) (737,656) (731,548) (725,379) (719,149) (712,856) (706,500) (700,081) Maintenance and Operating Costs ($) (130,020) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 390, , , , , , , ,769 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 692, , , , ,865 (5,232,078) (9,015,050) 331, , , , , , , , ,151 Discount Factor NPV 692, , , , ,940 (4,513,236) (7,549,962) 269, , , , , , , , ,517 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 671, , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , ,124 HW Sludge Hauling Costs 2 (693,598) (687,049) (680,436) (673,756) (667,009) (660,195) (653,312) (646,361) (639,341) (632,250) Maintenance Costs ($) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 866, , , , , , , , , ,918 Discount Factor NPV 540, , , , , , , , , ,239 Total NPV: 1,100, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes 95% utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

191 Net Present Value Base Case: Capital Cost Increase 20% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 33,468 33,223 32,976 32,726 32,474 32,219 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 33,468 33,223 32,976 32,726 32,474 32,219 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 80,258 79,671 79,078 78,479 77,874 77,263 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (7,092,012) (11,472,000) Electricity Revenue ($) 375, , , , , , , , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , , , , , , , ,124 HW Sludge Hauling Costs 3 (259,447) (253,862) (778,749) (773,052) (767,299) (761,488) (755,618) (749,690) (743,703) (737,656) (731,548) (725,379) (719,149) (712,856) (706,500) (700,081) Maintenance and Operating Costs ($) (156,024) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) Tipping Revenue ($) 390, ,981 1,171,767 1,163,196 1,154,538 1,145,794 1,136,962 1,128,043 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 692, , , , ,611 (6,146,334) (10,685,308) 531, , , , , , , , ,083 Discount Factor NPV 692, , , , ,829 (5,301,882) (8,948,777) 432, , , , , , , , ,826 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 671, , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , ,124 HW Sludge Hauling Costs 2 (693,598) (687,049) (680,436) (673,756) (667,009) (660,195) (653,312) (646,361) (639,341) (632,250) Maintenance Costs ($) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) (408,408) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 798, , , , , , , , , ,850 Discount Factor NPV 497, , , , , , , , , ,729 Total NPV: (900,000) 2020 Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes full utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

192 Net Present Value Base Case: Capital Cost Decrease 15% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 25,582 24,995 24,402 23,803 23,198 22,587 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (5,023,509) (8,126,000) Electricity Revenue ($) 375, , , , , , , , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , , , , , , , ,124 HW Sludge Hauling Costs 3 (259,447) (253,862) (248,222) (242,525) (236,771) (230,960) (225,091) (219,163) (743,703) (737,656) (731,548) (725,379) (719,149) (712,856) (706,500) (700,081) Maintenance and Operating Costs ($) (110,517) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) Tipping Revenue ($) 390, , , , , , , ,769 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 692, , , , ,865 (4,345,576) (7,561,547) 382, , , , , , , , ,202 Discount Factor NPV 692, , , , ,940 (3,748,532) (6,332,677) 311, , , , , , , , ,284 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 671, , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , ,124 HW Sludge Hauling Costs 2 (693,598) (687,049) (680,436) (673,756) (667,009) (660,195) (653,312) (646,361) (639,341) (632,250) Maintenance Costs ($) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) (289,289) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 917, , , , , , , , , ,969 Discount Factor NPV 572, , , , , , , , , ,621 Total NPV: 3,740, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes full utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

193 Net Present Value Base Case: Electricity Cost Increase 50% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 25,582 24,995 24,402 23,803 23,198 22,587 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (5,910,010) (9,560,000) Electricity Revenue ($) 562, , , , , , , ,872 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , , , , , , , ,124 HW Sludge Hauling Costs 3 (259,447) (253,862) (248,222) (242,525) (236,771) (230,960) (225,091) (219,163) (743,703) (737,656) (731,548) (725,379) (719,149) (712,856) (706,500) (700,081) Maintenance and Operating Costs ($) (130,020) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 390, , , , , , , ,769 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 879, , , , ,489 (5,044,454) (8,827,426) 519,262 1,227,691 1,224,639 1,221,557 1,218,444 1,215,299 1,212,123 1,208,916 1,205,676 Discount Factor NPV 879, , , , ,641 (4,351,390) (7,392,830) 422, , , , , , , , ,878 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 1,006,577 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , ,124 HW Sludge Hauling Costs 2 (693,598) (687,049) (680,436) (673,756) (667,009) (660,195) (653,312) (646,361) (639,341) (632,250) Maintenance Costs ($) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 1,202,404 1,199,099 1,195,762 1,192,390 1,188,986 1,185,547 1,182,073 1,178,565 1,175,022 1,171,443 Discount Factor NPV 749, , , , , , , , , ,488 Total NPV: 6,300, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes full utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

194 Net Present Value Base Case: Electricity Cost Decrease 20% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 25,582 24,995 24,402 23,803 23,198 22,587 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (5,910,010) (9,560,000) Electricity Revenue ($) 300, , , , , , , , , , , , , , , ,841 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , , , , , , , ,124 HW Sludge Hauling Costs 3 (259,447) (253,862) (248,222) (242,525) (236,771) (230,960) (225,091) (219,163) (743,703) (737,656) (731,548) (725,379) (719,149) (712,856) (706,500) (700,081) Maintenance and Operating Costs ($) (130,020) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 390, , , , , , , ,769 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 617, , , , ,816 (5,307,127) (9,090,100) 256, , , , , , , , ,941 Discount Factor NPV 617, , , , ,259 (4,577,975) (7,612,815) 208, , , , , , , , ,372 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 536, , , , , , , , , ,841 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , ,124 HW Sludge Hauling Costs 2 (693,598) (687,049) (680,436) (673,756) (667,009) (660,195) (653,312) (646,361) (639,341) (632,250) Maintenance Costs ($) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 732, , , , , , , , , ,708 Discount Factor NPV 456, , , , , , , , , ,139 Total NPV: (900,000) 2020 Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes full utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

195 Net Present Value Base Case: Natural Gas Cost Increase 50% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 25,582 24,995 24,402 23,803 23,198 22,587 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (5,910,010) (9,560,000) Electricity Revenue ($) 375, , , , , , , , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 279, , , , , , , , , , , , , , , ,186 HW Sludge Hauling Costs 3 (259,447) (253,862) (248,222) (242,525) (236,771) (230,960) (225,091) (219,163) (743,703) (737,656) (731,548) (725,379) (719,149) (712,856) (706,500) (700,081) Maintenance and Operating Costs ($) (130,020) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 390, , , , , , , ,769 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 785, , , , ,927 (5,139,016) (8,921,988) 424, , , , , , , , ,213 Discount Factor NPV 785, , , , ,624 (4,432,960) (7,472,025) 345, , , , , , , , ,250 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 671, , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 279, , , , , , , , , ,186 HW Sludge Hauling Costs 2 (693,598) (687,049) (680,436) (673,756) (667,009) (660,195) (653,312) (646,361) (639,341) (632,250) Maintenance Costs ($) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 959, , , , , , , , , ,980 Discount Factor NPV 598, , , , , , , , , ,686 Total NPV: 2,900, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes full utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

196 Net Present Value Base Case, Increase Hauling 15% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Base Case - Digester and HW at AD Capacity Discount Rate 3.00% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) Maintenance and Operating Cost Rate 2.20% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 1 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (lbs VS/day) 11,150 10,910 10,668 10,423 10,176 9,926 9,674 9,419 31,961 31,702 31,439 31,174 30,906 30,636 30,363 30,087 Received HW (gallons/day) 26,739 26,163 25,582 24,995 24,402 23,803 23,198 22,587 76,646 76,023 75,393 74,758 74,116 73,467 72,812 72,150 Biogas Produced (cf/day) 222, , , , , , , , , , , , , , , ,000 Electricity Generated (kwh) ,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) (5,910,010) (9,560,000) Electricity Revenue ($) 375, , , , , , , , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , , , , , , , ,124 HW Sludge Hauling Costs 3 (298,364) (291,941) (285,455) (278,904) (272,287) (265,604) (258,854) (252,037) (855,258) (848,304) (841,280) (834,186) (827,021) (819,784) (812,475) (805,093) Maintenance and Operating Costs ($) (130,020) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 390, , , , , , , ,769 1,119,034 1,109,934 1,100,744 1,091,462 1,082,088 1,072,619 1,063,056 1,053,397 Total 653, , , , ,349 (5,266,722) (9,048,814) 298, , , , , , , , ,139 Discount Factor NPV 653, , , , ,385 (4,543,120) (7,578,239) 242, , , , , , , , ,113 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 1 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (lbs VS/day) 29,808 29,527 29,242 28,955 28,665 28,373 28,077 27,778 27,476 27,172 Received HW (gallons/day) 71,482 70,807 70,126 69,437 68,742 68,040 67,331 66,614 65,891 65,160 Biogas Produced (cf/day) 397, , , , , , , , , ,000 Electricity Generated (kwh) 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 1,100 Construction Costs ($) Electricity Revenue ($) 671, , , , , , , , , ,051 Offset Cost of Heating Digest.&Bldgs ($) 186, , , , , , , , , ,124 HW Sludge Hauling Costs 2 (797,637) (790,107) (782,501) (774,819) (767,060) (759,224) (751,309) (743,316) (735,242) (727,087) Maintenance Costs ($) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) (340,340) Tipping Revenue ($) 1,043,641 1,033,788 1,023,837 1,013,786 1,003, , , , , ,333 Total 762, , , , , , , , , ,080 Discount Factor NPV 475, , , , , , , , , ,944 Total NPV: (300,000) 2020 Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 2024 Capital Costs = Phase 4 : Secondary Digester Upgrades 2025 Capital Costs = Phase 5 : Acid Phase Digester 1 Spreadsheet assumes 95% utilization of the digester. All digester capacity beyond that required for AWTF biosolids is assumed to be filled with Hauled Waste. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

197 Net Present Value HW at 30% of Digester Feed Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (5,910,100) Electricity Revenue ($) 377, , , , , , , , , , , , , , , ,013 Offset Cost of Heating Digest.&Bldgs ($) 111, , , , , , , , , , , , , , , ,295 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (239,336) (241,729) (244,146) (246,588) (249,054) (251,544) (254,060) (256,600) (259,166) (261,758) (264,376) (267,019) (269,689) (272,386) (275,110) (277,861) Maintenance and Operating Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 609, , , , , ,529 (5,263,471) 523, , , , , , , , ,517 Discount Factor NPV 609, , , , , ,526 (4,408,074) 425, , , , , , , , ,686 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 442, , , , , , , , , ,767 Offset Cost of Heating Digest.&Bldgs ($) 130, , , , , , , , , ,823 HW Sludge Hauling Costs 2 (280,640) (283,446) (286,281) (289,144) (292,035) (294,955) (297,905) (300,884) (303,893) (306,932) Maintenance Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 584, , , , , , , , , ,469 Discount Factor NPV 364, , , , , , , , , ,145 Total NPV: 6,000, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

198 Net Present Value HW at 30% of Digester Feed: Capital Cost Increase 20% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (7,092,120) Electricity Revenue ($) 377, , , , , , , , , , , , , , , ,013 Offset Cost of Heating Digest.&Bldgs ($) 111, , , , , , , , , , , , , , , ,295 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (239,336) (241,729) (244,146) (246,588) (249,054) (251,544) (254,060) (256,600) (259,166) (261,758) (264,376) (267,019) (269,689) (272,386) (275,110) (277,861) Maintenance and Operating Costs ($) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 609, , , , , ,529 (6,445,491) 497, , , , , , , , ,513 Discount Factor NPV 609, , , , , ,526 (5,397,997) 404, , , , , , , , ,995 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 442, , , , , , , , , ,767 Offset Cost of Heating Digest.&Bldgs ($) 130, , , , , , , , , ,823 HW Sludge Hauling Costs 2 (280,640) (283,446) (286,281) (289,144) (292,035) (294,955) (297,905) (300,884) (303,893) (306,932) Maintenance Costs ($) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) (156,027) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 558, , , , , , , , , ,465 Discount Factor NPV 348, , , , , , , , , ,725 Total NPV: 4,700, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

199 Net Present Value HW at 30% of Digester Feed: Capital Cost Decrease 15% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (5,023,585) Electricity Revenue ($) 377, , , , , , , , , , , , , , , ,013 Offset Cost of Heating Digest.&Bldgs ($) 111, , , , , , , , , , , , , , , ,295 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (239,336) (241,729) (244,146) (246,588) (249,054) (251,544) (254,060) (256,600) (259,166) (261,758) (264,376) (267,019) (269,689) (272,386) (275,110) (277,861) Maintenance and Operating Costs ($) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 609, , , , , ,529 (4,376,956) 542, , , , , , , , ,020 Discount Factor NPV 609, , , , , ,526 (3,665,632) 441, , , , , , , , ,205 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 442, , , , , , , , , ,767 Offset Cost of Heating Digest.&Bldgs ($) 130, , , , , , , , , ,823 HW Sludge Hauling Costs 2 (280,640) (283,446) (286,281) (289,144) (292,035) (294,955) (297,905) (300,884) (303,893) (306,932) Maintenance Costs ($) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) (110,519) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 603, , , , , , , , , ,972 Discount Factor NPV 376, , , , , , , , , ,460 Total NPV: 7,000, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

200 Net Present Value HW at 30% of Digester Feed: Electricity Cost Increase 50% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 35,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (5,910,100) Electricity Revenue ($) 565, , , , , , , , , , , , , , , ,020 Offset Cost of Heating Digest.&Bldgs ($) 111, , , , , , , , , , , , , , , ,295 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (239,336) (241,729) (244,146) (246,588) (249,054) (251,544) (254,060) (256,600) (259,166) (261,758) (264,376) (267,019) (269,689) (272,386) (275,110) (277,861) Maintenance and Operating Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 797, , , , , ,794 (5,063,376) 725, , , , , , , , ,524 Discount Factor NPV 797, , , , , ,551 (4,240,498) 589, , , , , , , , ,258 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 663, , , , , , , , , ,650 Offset Cost of Heating Digest.&Bldgs ($) 130, , , , , , , , , ,823 HW Sludge Hauling Costs 2 (280,640) (283,446) (286,281) (289,144) (292,035) (294,955) (297,905) (300,884) (303,893) (306,932) Maintenance Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 805, , , , , , , , , ,352 Discount Factor NPV 502, , , , , , , , , ,670 Total NPV: 9,900, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

201 Net Present Value HW at 30% of Digester Feed: Electricity Cost Decrease 20% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (5,910,100) Electricity Revenue ($) 301, , , , , , , , , , , , , , , ,411 Offset Cost of Heating Digest.&Bldgs ($) 111, , , , , , , , , , , , , , , ,295 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (239,336) (241,729) (244,146) (246,588) (249,054) (251,544) (254,060) (256,600) (259,166) (261,758) (264,376) (267,019) (269,689) (272,386) (275,110) (277,861) Maintenance and Operating Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 533, , , , , ,223 (5,343,509) 442, , , , , , , , ,914 Discount Factor NPV 533, , , , , ,115 (4,475,105) 359, , , , , , , , ,457 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 353, , , , , , , , , ,013 Offset Cost of Heating Digest.&Bldgs ($) 130, , , , , , , , , ,823 HW Sludge Hauling Costs 2 (280,640) (283,446) (286,281) (289,144) (292,035) (294,955) (297,905) (300,884) (303,893) (306,932) Maintenance Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 496, , , , , , , , , ,716 Discount Factor NPV 309, , , , , , , , , ,935 Total NPV: 4,500, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

202 Net Present Value HW at 30% of Digester Feed: Natural Gas Cost Increase 50% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (5,910,100) Electricity Revenue ($) 377, , , , , , , , , , , , , , , ,013 Offset Cost of Heating Digest.&Bldgs ($) 167, , , , , , , , , , , , , , , ,943 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (239,336) (241,729) (244,146) (246,588) (249,054) (251,544) (254,060) (256,600) (259,166) (261,758) (264,376) (267,019) (269,689) (272,386) (275,110) (277,861) Maintenance and Operating Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 664, , , , , ,053 (5,204,361) 583, , , , , , , , ,165 Discount Factor NPV 664, , , , , ,009 (4,358,571) 474, , , , , , , , ,181 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 442, , , , , , , , , ,767 Offset Cost of Heating Digest.&Bldgs ($) 195, , , , , , , , , ,234 HW Sludge Hauling Costs 2 (280,640) (283,446) (286,281) (289,144) (292,035) (294,955) (297,905) (300,884) (303,893) (306,932) Maintenance Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 649, , , , , , , , , ,880 Discount Factor NPV 404, , , , , , , , , ,252 Total NPV: 7,200, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

203 Net Present Value HW at 30% of Digester Feed, Hauling Increased by 15% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: HW at 30% of Total Digester Feed Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 HW Limited to 30% of AD Feed 1 (lbs VS/day) 10,286 10,389 10,492 10,597 10,703 10,810 10,918 11,028 11,138 11,249 11,362 11,475 11,590 11,706 11,823 11,941 Received HW (gallons/day) 24,666 24,913 25,162 25,413 25,668 25,924 26,183 26,445 26,710 26,977 27,247 27,519 27,794 28,072 28,353 28,636 Biogas Produced (cf/day) 223, , , , , , , , , , , , , , , ,056 Electricity Generated (kwh) Construction Costs ($) (5,910,100) Electricity Revenue ($) 377, , , , , , , , , , , , , , , ,013 Offset Cost of Heating Digest.&Bldgs ($) 111, , , , , , , , , , , , , , , ,295 Total Sludge Hauling Cost Savings by Thickening HW Sludge Hauling Costs 3 (275,236) (277,988) (280,768) (283,576) (286,412) (289,276) (292,169) (295,090) (298,041) (301,022) (304,032) (307,072) (310,143) (313,244) (316,377) (319,541) Maintenance and Operating Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 360, , , , , , , , , , , , , , , ,092 Total 573, , , , , ,797 (5,301,580) 484, , , , , , , , ,838 Discount Factor NPV 573, , , , , ,978 (4,439,990) 394, , , , , , , , ,934 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 HW Limited to 30% of AD Feed 1 (lbs VS/day) 12,061 12,181 12,303 12,426 12,551 12,676 12,803 12,931 13,060 13,191 Received HW (gallons/day) 28,923 29,212 29,504 29,799 30,097 30,398 30,702 31,009 31,319 31,632 Biogas Produced (cf/day) 261, , , , , , , , , ,160 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 442, , , , , , , , , ,767 Offset Cost of Heating Digest.&Bldgs ($) 130, , , , , , , , , ,823 HW Sludge Hauling Costs 2 (322,736) (325,963) (329,223) (332,515) (335,840) (339,199) (342,591) (346,017) (349,477) (352,972) Maintenance Costs ($) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) (130,022) Tipping Revenue ($) 422, , , , , , , , , ,834 Total 542, , , , , , , , , ,429 Discount Factor NPV 337, , , , , , , , , ,156 Total NPV: 5,300, Capital Costs = Phase 2 : WAS Thickening and Hauled Waste & Phase 3 : CHP 1 Spreadsheet assumes hauled waste received is limited to 30% of total digester feed. 2 Cost for hauling digested, dewatered hauled waste. Assumes 60% destruction of VS from HW and digested sludge is dewatered to 22% dry solids. N:\ \Engineering\Cost_Est

204 Net Present Value Without Hauled Waste Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Without Hauled Waste Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 35,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 144, , , , , , , , , , , , , , , ,180 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 195, , , , , , , , , , , , , , , ,638 Offset Cost of Heating Digest.&Bldgs ($) 71,871 72,589 73,315 74,048 74,789 75,537 76,292 77,055 77,826 78,604 79,390 80,184 80,986 81,795 82,613 83,439 HW Sludge Hauling Costs Maintenance and Operating Costs ($) Tipping Revenue ($) Total 267, , , , , , , , , , , , , , , ,078 Discount Factor NPV 267, , , , , , , , , , , , , , , ,027 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 168, , , , , , , , , ,670 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 228, , , , , , , , , ,350 Offset Cost of Heating Digester & Bldgs ($) 82,613 83,439 82,613 83,439 82,613 83,439 82,613 83,439 82,613 83,439 HW Sludge Hauling Costs Maintenance Costs ($) Tipping Revenue ($) Total 311, , , , , , , , , ,789 Discount Factor NPV 194, , , , , , , , , ,420 Total NPV: 5,500, Capital Costs = Phase 2 : WAS Thickening without Hauled Waste (Estimated at 67% of full Phase 3 cost with Hauled Waste) & Phase 3 : Estimated at 80% of Full Capacity CHP Cost N:\ \Engineering\Cost_Est

205 Net Present Value Without Hauled Waste: Electricity Cost Increase 50% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Without Hauled Waste Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 144, , , , , , , , , , , , , , , ,180 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 292, , , , , , , , , , , , , , , ,958 Offset Cost of Heating Digest.&Bldgs ($) 71,871 72,589 73,315 74,048 74,789 75,537 76,292 77,055 77,826 78,604 79,390 80,184 80,986 81,795 82,613 83,439 HW Sludge Hauling Costs Maintenance and Operating Costs ($) Tipping Revenue ($) Total 364, , , , , , , , , , , , , , , ,397 Discount Factor NPV 364, , , , , , , , , , , , , , , ,762 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 168, , , , , , , , , ,670 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 343, , , , , , , , , ,525 Offset Cost of Heating Digester & Bldgs ($) 82,613 83,439 82,613 83,439 82,613 83,439 82,613 83,439 82,613 83,439 HW Sludge Hauling Costs Maintenance Costs ($) Tipping Revenue ($) Total 425, , , , , , , , , ,964 Discount Factor NPV 265, , , , , , , , , ,204 Total NPV: 7,500, Capital Costs = Phase 2 : WAS Thickening without Hauled Waste (Estimated at 67% of full Phase 3 cost with Hauled Waste) & Phase 3 : Estimated at 80% of Full Capacity CHP Cost N:\ \Engineering\Cost_Est

206 Net Present Value Without Hauled Waste: Electricity Cost Decrease 20% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Without Hauled Waste Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 144, , , , , , , , , , , , , , , ,180 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 156, , , , , , , , , , , , , , , ,311 Offset Cost of Heating Digest.&Bldgs ($) 71,871 72,589 73,315 74,048 74,789 75,537 76,292 77,055 77,826 78,604 79,390 80,184 80,986 81,795 82,613 83,439 HW Sludge Hauling Costs Maintenance and Operating Costs ($) Tipping Revenue ($) Total 228, , , , , , , , , , , , , , , ,750 Discount Factor NPV 228, , , , , , , , , , , , , , , ,933 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 168, , , , , , , , , ,670 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 183, , , , , , , , , ,280 Offset Cost of Heating Digester & Bldgs ($) 82,613 83,439 82,613 83,439 82,613 83,439 82,613 83,439 82,613 83,439 HW Sludge Hauling Costs Maintenance Costs ($) Tipping Revenue ($) Total 265, , , , , , , , , ,719 Discount Factor NPV 165, , , , , , , , , ,506 Total NPV: 4,700, Capital Costs = Phase 2 : WAS Thickening without Hauled Waste (Estimated at 67% of full Phase 3 cost with Hauled Waste) & Phase 3 : Estimated at 80% of Full Capacity CHP Cost N:\ \Engineering\Cost_Est

207 Net Present Value Without Hauled Waste: Natural Gas Increase 50% Client: Capital Region Water Electricity Generated ($/kwh) Project: Biosolids Facilities Improvement Plan Tipping Fee ($/1000 gallons) 40 NPV Scenario: Without Hauled Waste Discount Rate 3% Last Modified: 3/12/2018 Hauling Cost ($/wet ton) 33 Maintenance and Operating Cost Rate 2.2% Year Digester Capacity (lbs VS/day) 37,000 37,000 37,000 37,000 37,000 37,000 37,000 37,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 24,000 24,240 24,482 24,727 24,974 25,224 25,476 25,731 25,989 26,248 26,511 26,776 27,044 27,314 27,587 27,863 Available Capacity for HW (lbs VS/day) 13,000 12,760 12,518 12,273 12,026 11,776 11,524 11,269 35,011 34,752 34,489 34,224 33,956 33,686 33,413 33,137 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 144, , , , , , , , , , , , , , , ,180 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 195, , , , , , , , , , , , , , , ,638 Offset Cost of Heating Digest.&Bldgs ($) 107, , , , , , , , , , , , , , , ,159 HW Sludge Hauling Costs Maintenance and Operating Costs ($) Tipping Revenue ($) Total 303, , , , , , , , , , , , , , , ,798 Discount Factor NPV 303, , , , , , , , , , , , , , , ,805 Year Digester Capacity (lbs VS/day) 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 61,000 AWTF Biosolids Generated (lbs VS/day) 28,142 28,423 28,708 28,995 29,285 29,577 29,873 30,172 30,474 30,778 Available Capacity for HW (lbs VS/day) 32,858 32,577 32,292 32,005 31,715 31,423 31,127 30,828 30,526 30,222 Received HW (lbs VS/day) Received HW (gallons/day) Biogas Produced (cf/day) 168, , , , , , , , , ,670 Electricity Generated (kwh) Construction Costs ($) Electricity Revenue ($) 228, , , , , , , , , ,350 Offset Cost of Heating Digester & Bldgs ($) 123, , , , , , , , , ,159 HW Sludge Hauling Costs Maintenance Costs ($) Tipping Revenue ($) Total 352, , , , , , , , , ,509 Discount Factor NPV 219, , , , , , , , , ,345 Total NPV: 6,200, Capital Costs = Phase 2 : WAS Thickening without Hauled Waste (Estimated at 67% of full Phase 3 cost with Hauled Waste) & Phase 3 : Estimated at 80% of Full Capacity CHP Cost N:\ \Engineering\Cost_Est

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