Table of Contents. Section 8 Detailed Description of Recommended Treatment Alternative

Transcription

1 Table of Contents List of Tables 8.1 Description of Treatment Alternatives Flow-Split Options Investigated New Water Reclamation Campus New WRC Treatment New Water Reclamation Campus Conceptual Design New Water Reclamation Campus Permits Ina Road WRF Ina Road WRF Treatment Process Ina Road WRF Conceptual Basis of Design Ina Road WRF Permits Conveyance Effluent Quality Permit Requirements Pathogen Removal Salinity Contaminants of Concern Water Reuse Considerations Estimated Future Biosolids Production Water Reclamation Campus Biosolids Ina Road WRF Biosolids Design Phases New Water Reclamation Campus at Roger Road Ina Road WRF Project Timeline Stormwater Plan Table 8-1 New Water Reclamation Campus Anticipated Permits Table 8-2 Ina Road WRF Anticipated Permits i J:\Projects\Pima Co WM\05305\06 Gen Studies-Rpts\6.1 Reports\ Plan\08Jul30 Submittal\Section 8_08Jul30.doc

2 List of Figures Table of Contents Figure 8-1 New WRC at Roger Road Year 2030 Master Plan Layout Figure 8-2 Ina Road WRF Year 2030 Master Plan Layout Figure 8-3 Conveyance Capital Improvement Projects Figure 8-4 ROMP Project Timeline ii J:\Projects\Pima Co WM\05305\06 Gen Studies-Rpts\6.1 Reports\ Plan\08Jul30 Submittal\Section 8_08Jul30.doc

3 Section 8 Alternative Detailed Description of Recommended Treatment 8.1 Description of Treatment Alternatives There were various treatment strategies studied to treat the wastewater from the two large metropolitan service areas. A number of biological treatment processes are available to meet the goal of future effluent limits for nutrients by January 2014 at the Ina Road WRF and January 2015 at the WRC at Roger Road. It is anticipated that future limits will be: Ammonia nitrogen concentration of 2 mg/l or less Total nitrogen concentration of 8 mg/l or less Biological treatment processes are available that effectively remove nitrogen to meet the stated effluent goals. There were suspended growth systems, attached growth systems and integrated systems studied. The list of the processes researched includes: Suspended Growth System Modified Ludzack-Ettinger (MLE) Bardenpho Step feed activated sludge system for nitrification-denitrification (NdeN) Attached Growth System Biological Aerated Filters (BAF) and Denitrifying Sand Filters Moving bed (MBBRs) Trickling Filter (Biotowers) Integrated System Integrated fixed film activated sludge (IFAS) Membrane in activated sludge system, membrane bioreactor (MBR) It was decided the most effective process would be the Bardenpho process. The Bardenpho process was determined the most reliable and cost effective process and is recommended for use at both treatment plants Flow-Split Options Investigated Splitting the flow between the two plants is economically necessary to serve the combined service areas. Based on the projected 2030 flows, various flow-split options were considered so that a cost effective treatment strategy could be chosen for the County. The three options evaluated were: Option 1 Based on a flow split of 32-mgd and 50-mgd between Roger Road Wastewater Reclamation Facility (WRF) and Ina Road WRF, respectively. Option 2 Based on some flow transfer from the Roger Road WRF to the Ina Road WRF to make a flow split of 20-mgd and 62-mgd, respectively,. 8-1

4 Option 3 Based on transferring all flow from the Roger Road WRF to the Ina Road WRF and therefore treatment of all 82-mgd at the Ina Road WRF. The decision to proceed with the Bardenpho process allowed for these various options to be further investigated based on both technical and economic criteria. It was determined that a capacity of 32-mgd at Roger Road WRF and 50-mgd at Ina Road WRF was the most cost effective option. 8.2 New Water Reclamation Campus At the existing Roger Road WRF there is a vacate and open spaces south as well as north of the existing Roger Road WRF for construction of a new 32-mgd wastewater treatment facility. The southern open space would place the site west of the existing Tucson water reclaimed water filtration plant, reservoir and pumping station operations. The location along Sweetwater Drive meets the regulatory requirements for 350-foot setbacks using City of Tucson owned land. A site to the north of the existing treatment works would most likely be located adjacent to the Santa Cruz River and removed from existing operation. Further, the site to the north can expand on the environmental theme for future park consideration. Because of the construction issues and integration with the potential future park theme the north site is recommended. The existing facilities will continue operations until the new facilities are commissioned and then the existing facilities will be decommissioned and demolished. The new Water Reclamation Campus (WRC) at Roger Road will be contained on a site of approximately 16 acres and be located north of the existing Roger Road WRF. The proposed land where the facility will be constructed is owned by Pima County. Pima County Regional Wastewater Reclamation Department (PCRWRD) will own the new WRC. With a chosen location north of the existing plant, a new influent pumping station will be constructed adjacent to the new facility. Tucson Water will construct a new reuse water supply system with new pump station to provide reuse water from the new effluent disinfection facilities to their operation. A new recommended central laboratory will house appropriate laboratory area functions for regulatory compliance analysis to be performed. The central laboratory function will be combined with personnel functions in a new facility to be located at or near the new WRC. There is also a need for plant laboratory space for routine, unit process monitoring of operations. Such plant lab spaces will be incorporated into structures adjacent to and serving the various unit processes at the new WRC New WRC Treatment Recommendations for Roger Road are to construct a new 32-mgd wastewater treatment facility using Bardenpho technology to meet the stringent standards imposed by the Arizona Department of Environmental Quality (ADEQ). This treatment technology will be configured to be amenable to adaption for meeting future imposed regulations. The facility will be constructed as a 32-mgd wastewater treatment facility with sludge sent to the Ina Road WRF for processing. The basic treatment system components include: Headworks Facilities Influent Pump Station 8-2

5 Influent Screening Facilities Influent Grit Removal Facilities Odor Control Facilities Aeration Tanks (Bardenpho Process) Blower Facilities Secondary Sedimentation Facilities Disinfection Sludge Thickening Sludge Transfer Pump Station Appendix B contains the ADEQ Checklist for the new WRC at Roger Road and provides information on the proposed plant New Water Reclamation Campus Conceptual Design The following tables detail the conceptual basis of design for the New WRC at Roger Road facilities. Wastewater Quantities Gallons per Capita per Day 85 Annual Average Flow, mgd 24 Monthly Peak (1.1 x an. avg. flow), mgd 26 Daily Peak (1.4 x an. avg. flow), mgd 33 Hourly Peak (2.0 x an. avg. flow), mgd 48 Raw Influent Wastewater Characteristics Total Suspended Solids, mg/l 286 lbs/day 57,000 Chemical Oxygen Demand, mg/l 648 lbs/day 130,000 5-day Biochemical Oxygen Demand, mg/l 294 lbs/day 59,000 Soluble 5-day Biochemical Oxygen Demand, mg/l 121 lbs/day 24,000 Volatile Suspended Solids, mg/l 225 lbs/day 45,000 Total Kjeldahl Nitrogen, mg/l 47 lbs/day 9,400 Total Phosphorous - mg/l 10 lbs/day 2,000 Influent Screening Facilities Mechanically Bar Screen Type cleaned Coarse, number of units 2 Clear opening, in. 2.5 Fine number of units 3 Clear opening, mm 3 8-3

6 Screenings Removal Screenings Removed cu ft/mg 10 cu ft/day (an. avg.) 240 Screenings removal support equipment Screen Belt Conveyors Screenings Compactor Influent Grit Facilities Type Vortex Number of Units 2 Capacity per unit, mgd 24 Grit Removal Grit Removed cu ft/mg 6 cu ft/day (an. avg.) 144 System Performance 95% of 65 mesh grit Odor Control At preliminary treatment, wastewater treatment, and sludge thickening facilities Treatment Wastewater Characteristics 1 Total Suspended Solids, mg/l 310 lbs/day 62,000 Chemical Oxygen Demand, mg/l 659 lbs/day 131,800 5-day Biochemical Oxygen Demand, mg/l 301 lbs/day 60,200 Soluble 5-day Biochemical Oxygen Demand, mg/l 121 lbs/day 24,200 Volatile Suspended Solids, mg/l 243 lbs/day 48,600 Total Kjeldahl Nitrogen, mg/l 47 lbs/day 9,400 Total Phosphorous, mg/l 10 lbs/day 2,000 Aeration Tanks 2 Number of tanks 4 Volume per tank (new) 702,000 cu. ft Number of Stages per Tank 5 Return sludge, % 50 Internal recycle, % Includes plant recycle 2 Includes future biological phosphorous removal provisions (based on Bardenpho process) 8-4

7 Final Clarifiers Type Circular Number of Tanks 4 Clarifier diameter. ft. 150 Sidewater Depth, ft. 12 Total Surface Area of Tanks, sf 53,000 Surface Loading An. Avg., gal/sf/day 450 Peak, gal/sf/day 900 Final Clarifier Tank Effluent Suspended Solids, mg/l 7 BOD, mg/l 7 NH 3 -N, mg/l < 1 TN, mg/l < 8 Disinfection (Chlorine Technology) Number of Basins 4 Detention an. avg. flow, min. 90 Sodium Hypochlorite max. capacity mg/l 15 Bisulfite max. capacity, mg/l 22 Sludge Thickening Facilities Waste Activated Sludge to Thickening, Avg. Values Flow, mgd 1.72 Mass, lbs/day 100,600 Conc., mg/l 7,000 Gravity Belt Thickeners Thickener Effective Width, m 2 Design Sludge Flow per Thickener, gpm 500 Number of Existing Units (relocated) 1 Number of New Units 3 Number of Thickeners Operating 3 Number of Thickeners Installed 4 Future Provision 2 units Capture Efficiency, % 90 Polymer systems, number 2 Thickened Sludge Pumped to Ina Road Flow, mgd 0.26 Mass, lbs/day 65,600 Conc., % solids 3 Sludge Transfer Pump Station Thickened Waste Activated Sludge to Ina Road Number of pumps 2 Rate, gpm

8 The 2030 master plan layout for the facilities at the new WRC at Roger Road is illustrated in Figure 8-1. Figure 8-1 New WRC at Roger Road Year 2030 Master Plan Layout New Water Reclamation Campus Permits All of the permits required for the new WRC will be obtained in a timely fashion to ensure progress to final completion of the recommended facility. The permits required can be found on Table

9 Table 8-1 New Water Reclamation Campus Anticipated Permits Anticipated Permits Required For New Roger Road WRC Air Quality Permit Approval to Construct Approval of Construction Aquifer Protection Permit (APP) Architectural Approval AZPDES Permit Building Permit Certificate of Occupancy Construction Authorization Grading and Drainage Permit Hazardous Materials Management Plan NPDES Reclaimed Water Reuse Permit Section 208 Plan Amendment SWPPP USF and WS Permit 8.3 Ina Road WRF The future facilities at Ina Road will treat 50-mgd of wastewater and will be the centralized location for handling and treatment of biosolids. The recommended plan includes addition of new facilities and rehabilitation of the existing facilities while maintaining the existing 350-foot setback. Space is allocated for additional facilities to produce of Class A biosolids in the future. The project area for the modifications and expansion of the Ina Road WRF is approximately 150 acres. The proposed land where the facility will be constructed is owned by Pima County. When completed, the Ina Road WRF will continue to be owned and operated by the PCRWRD. The existing flow split structure will be modified to distribute the flow to existing primary clarifiers as well as to new primary clarifiers. The existing flow split structures from primary effluent through the secondary treatment system will also be modified. A new effluent discharge structure will be constructed to handle the effluent from the disinfection system and outfall conduit. A reuse water system will be constructed to supply reuse water to the water distribution network. The facility will release a Class B+ reuse quality effluent and Tucson Water will create the necessary facilities to handle this reclaimed water quality. The effluent will be near Class A+ water on a continuous basis Ina Road WRF Treatment Process The Ina Road WRF will have onsite facilities upgraded and expanded to meet the regulatory and growth needs of Pima County over the next 25 years. The wastewater treatment process will be based on 8-7

10 Bardenpho technology to meet the stringent standards imposed by the ADEQ. The plant will handle and treat the solids from both the WRC and the Ina Road WRF. Currently Pima County wastewater treatment operations produces a Class B biosolids. These biosolids are distributed from the Ina Road WRF and land applied. In the future the plant may produce a Class A biosolids which also would be centrally distributed from Ina Road. Cost and space requirements for Class A biosolids is based on the temperature phased anaerobic digestion technology. The basic treatment system components included in the Ina Road WRF are: New Influent Pump New Influent Grit Removal Facilities Odor Control Primary Clarifiers Aeration Tanks (Bardenpho Process) Blower Facilities Secondary Sedimentation Facilities Disinfection Sludge Thickening Facilities Sludge Digestion Facilities Sludge Dewatering Facilities Sludge Transfer Pump Station The Ina Road WRF will be enclosed in a screen wall system that provides elements of security, as well as an overall site-unifying device for plant aesthetics. Additional plant laboratory spaces will be provided in structures adjacent to and serving the various unit processes associated with expansion facilities The ADEQ Checklist for the Ina Road WRF can be found in Appendix C and provides information on the proposed expansions and modifications to the plant Ina Road WRF Conceptual Basis of Design The following tables detail the conceptual basis of design for the modified/expanded Water Reclamation Facilities at Ina Road. Wastewater Quantities Gallons per Capita per Day 85 Annual Average Flow, mgd 50 Monthly Peak (1.1 x an. avg. flow), mgd 55 Daily Peak (1.4 x an. avg. flow), mgd 70 Hourly Peak (2.0 x an. avg. flow), mgd 100 Raw Influent Wastewater Characteristics Total Suspended Solids, mg/l 286 lbs/day 120,000 Chemical Oxygen Demand, mg/l 663 lbs/day 278,

11 5-day Biochemical Oxygen Demand, mg/l 318 lbs/day 133,000 Soluble 5-day Biochemical Oxygen Demand, mg/l 123 lbs/day 52,000 Volatile Suspended Solids, mg/l 254 lbs/day 107,000 Total Kjeldahl Nitrogen, mg/l 55 lbs/day 23,000 Total Phosphorous 11 lbs/day 4,600 Influent Screening Facilities Mechanically Bar Screen Type cleaned Coarse, number of existing units 2 Clear opening, in. 2.5 Fine number of existing units 3 Clear opening, mm 3 Screenings Removal Screenings Removed cu ft/mg 10 cu ft/day (an. avg.) 500 Screenings removal support equipment Screenings Belt Conveyors Screenings Compactor Aerated Grit Influent Grit Facilities Channels Type Number of units Existing 3 New 1 Grit Removal Grit Removed cu ft/mg 6 cu ft/day (an. avg.) 300 System Performance 95% of 65 mesh grit Odor Control 1 At primary treatment, wastewater treatment, sludge dewatering, sludge thickening, and sludge loading station facilities Raw Sewage Pumping Station Pumps, type Archimedes screw Existing units 3 8-9

12 New 1 Capacity, mgd 35 1 Preliminary treatment odor control exists. Primary Influent Wastewater Characteristics 2 Total Suspended Solids - mg/l 358 lbs/day 149,000 Chemical Oxygen Demand, mg/l 689 lbs/day 287,000 5-day Biochemical Oxygen Demand - mg/l 324 lbs/day 135,000 Soluble 5-day Biochemical Oxygen Demand - mg/l 123 lbs/day 51,000 Volatile Suspended Solids - mg/l 282 lbs/day 118,000 Total Kjeldahl Nitrogen - mg/l 63 lbs/day 26,000 Total Phosphorous - mg/l 15 lbs/day 6,300 Primary Clarifiers Type Rectangular Existing 6 New 2 Clarifier Length, ft 216 Clarifier Width, ft 40 Sidewater Depth at influent end, ft 12 Total surface area, sf 69,000 Surface an. avg. flow, gal/sf/day Includes plant recycle Primary Influent Wastewater Characteristics 2 Total Suspended Solids - mg/l 146 lbs/day 61,000 Chemical Oxygen Demand, mg/l 456 lbs/day 190,000 5-day Biochemical Oxygen Demand - mg/l 229 lbs/day 96,000 Soluble 5-day Biochemical Oxygen Demand - mg/l 126 lbs/day 53,000 Volatile Suspended Solids - mg/l 123 lbs/day 51,000 Total Kjeldahl Nitrogen - mg/l 61 lbs/day 26,

13 Total Phosphorous - mg/l 14 lbs/day 5,900 Aeration Tank 3 Number of tanks Existing (with modified stages) 2 New 6 Volume per tank 752,000 cu. ft. Number of Stages per Tank 5 Return sludge, % 50 Internal recycle, % Includes future biological phosphorous removal provisions (based on Bardenpho process) Final Clarifiers Type Circular Number of Tanks 7 Existing 115 ft dia., 135 ft dia.) 3 New 115 ft. dia., 135 ft dia.) 12 Sidewater Depth, ft 119,600 Total Surface Area of Tanks, sq. ft Surface Loading 420 An. Avg., gal/sf/day 840 Peak, gal/sf/day Final Clarifier Tank Effluent Suspended Solids, mg/l 7 BOD, mg/l 7 NH 3 -N, mg/l < 1 TN, mg/l < 8 Disinfection (Chlorine Technology) Number of Basins Existing 2 New 2 Detention an. avg. flow, min. 90 Sodium Hypochlorite max. capacity, mg/l 15 Bisulfite max. capacity, mg/l 22 Primary Sludge Thickening Facilities Primary Sludge, Avg. Flow, mgd 1.14 Mass, lbs/day 94,700 Conc., % 1 Gravity Thickeners for Raw Primary Sludge 8-11

14 Number of Units 4 Diameter, ft 40 Sidewater Depth, ft 10 Area per Tank, sf 1,260 Total Area 5,040 Active Volume per tank, MG Volume, MG 0.38 Overflow Rate, gpd/sf Solids Only 225 Solids Only (1 out of service) 300 Solids and Max. Dilution Water 500 Maximum Dilution Water, mgd 1.38 Detention Time (@ max. dilution water, hr) 3.6 Solids Capture Efficiency, % 90 Thickened Primary Sludge, Avg. Flow, mgd 0.23 Mass, lbs/day 85,300 Conc., % 4.5 Water Activated Sludge Thickening Facilities Waste Activated Sludge, Avg. Flow, mgd 1.35 Mass, lbs/day 78,700 Conc., mg/l 7,000 Gravity Belt Thickeners Thickener Effective Width, m 2 Design Sludge Flow per Thickener, gpm 500 Number of Thickeners Operating 2 Number of Thickeners Installed 3 Capture Efficiency 90% Polymer systems, number 2 Thickened Waste Activated Sludge Flow, mgd 0.19 Mass, lbs/day 70,800 Conc., % solids 4.5 Sludge Digesters, type Mesophilic Ina Road Thickened Primary Sludge Flow, mgd 0.23 Mass, lbs/day 85,300 Conc., % solids 4.5 Ina Road Thickened Waste Activated Sludge Flow, mgd 0.19 Mass, lbs/day 70,

15 Conc., % solids 4.5 WRC Thickened Waste Activated Sludge Flow, mgd 0.36 Mass, lbs/day 90,500 Conc., % solids 3 Total Influent Sludge Flow, mgd 0.78 Mass, lbs/day 247,100 Conc., % solids 3.8 Percent Volatile Solids 76 Volatile Solids, lbs/day 187,800 Total Number of Digesters 10 HRT, days 17.0 HRT (one unit out of service), days 15.3 Volatile Solids Loading, lb/d/1,000cf 105 Volatile Solids Loading (one unit out of service), lb/d/1,000cf 117 Volatile Solids Destruction, % 50 Digested Sludge Flow, mgd 0.78 Mass, lbs/day 153,200 Conc., % solids 2.4 Volatile Solids, lbs/day 93,900 Gas Production cf/lb Volatile Solids Destroyed 12 Total cf/day produced 1,100 Sludge Centrifuge Thickening/Dewatering Facilities Influent Digested Sludge Flow, mgd 0.68 Mass, lbs/day 153,200 Conc., % solids 2.4 Centrifuges Operate for Thickening or Dewatering Number of Existing Units 3 Number of New Units 4 Future Provision 1 unit Flow rate per Unit (24/7 operation), gpm 80 Flow rate per Unit (24/7 operation) one unit out of service, gpm 95 Flow rate per Unit (24/5 operation), gpm 110 Flow rate per Unit (24/5 operation) 8-13

16 one unit out of service, gpm 132 Flow rate per Unit (8/5 operation), gpm 400 Flow rate per Unit (8/5 operation) one unit out of service, gpm 495 Capture Efficiency, % 95 Polymer systems, number 2 Thickened Sludge Flow, mgd 0.20 Mass, lbs/day 130,600 Conc., % solids 8 Dewatered Sludge Mass, lbs/day 130,600 Conc., % solids 20 Thickened or Pre-thickening Sludge Storage Digested Sludge (Unthickened) Flow, mgd 0.78 Mass, lbs/day 153,200 Conc., % solids 2.4 Thickened Sludge Flow, mgd 0.20 Mass, lbs/day 130,600 Conc., % solids 8 Storage Capacity, MG 2.5 Detention Time for Unthickened Digested Sludge, days 3.2 Detention Time for Thickened Digester Sludge, days 12.5 Sludge Loading Station Sludge pump, gpm 300 Units 2 The 2030 master plan layout for the facilities at the Ina Road WRF is illustrated in Figure

17 Figure 8-2 Ina Road WRF Year 2030 Master Plan Layout Ina Road WRF Permits All of the permits required for the Ina Road WRF will be obtained in a timely fashion to ensure progress to final completion of the recommended facility. The permits required can be found in Table 8-2 Ina Road WRF Anticipated Permits. 8-15

18 Table 8-2 Ina Road WRF Anticipated Permits Anticipated Permits Required For Ina Road WRF Air Quality Permit Approval to Construct Approval of Construction Aquifer Protection Permit (APP) Architectural Approval AZPDES Permit Building Permit Certificate of Occupancy Construction Authorization Grading and Drainage Permit Hazardous Materials Management Plan NPDES Reclaimed Water Reuse Permit Section 208 Plan Amendment SWPPP USF and WS Permit 8.4 Conveyance Wastewater conveyance between the two large metropolitan treatment plants is required in the near future because of the increasing capacity requirements within the Roger Road service area and the lack of sufficient capacity. The construction of a plant interconnect pipeline is included within the ROMP program and will ensure that the two plants will be able to serve the population expected in the service area through the year Ability to transfer flow between the Roger Road service area and the Ina Road WRF is critical for the management of wastewater to accommodate growth. Based on current growth projections, it is anticipated that Roger Road WRF s capacity will be reached by the year 2011, or The plant interconnect pipeline, or some other method of transferring supplemental flows, to the Ina Road WRF must be placed into operation by this time. Because of the capacity limitations at the Roger Road WRF, there is an urgency in advancing the construction of the plant interconnect pipeline (Santa Cruz Interceptor Phase IV). The hydraulic analyses and the unit costs development were compiled to develop a CIP for the conveyance system over the 25-year planning period. Locations of recommended conveyance system improvements are indicated in Figure 8-3. The 2030 wet weather flow simulation was the primary means of determining which sewers would require upsizing. Details of the conveyance system modifications are provided in Section 6 of the ROMP, dated November In addition to odor control at the treatment facilities, the conveyance system was evaluated for odor control. The goal of the system is to contain and treat odors in the conveyance system including piping, and diversion structures. 8-16

19 Figure 8-3 Conveyance Capital Improvement Projects 8.5 Effluent Quality Permit Requirements Regulatory objectives for effluent quality are currently established by each facility s AZPDES and APP permits. Limits in the AZPDES permits are driven by State Surface Water Quality Standards. Limits in the APP permits are driven by numeric State Aquifer Water Quality Standards and BADCT requirements. The foremost goal is to meet permit requirements for elimination of ammonia toxicity and anticipated future total nitrogen limits at the Roger Road WRF and Ina Road WRF. Specific Letters of Intent with 8-17

20 capacity and wastewater treatment processes for the Roger Road WRF and Ina Road WRF were both issued on January 26, 2007 and can be found in Appendix D. In the future, the existing treatment system may require upgrades to meet more stringent regulatory criteria and the demand by customers for higher quality effluent and to reduce risk. Key factors in determining future treatment strategies include pathogen removal, salinity, contaminants of concern, future customer requirements, and risk associated with chlorine use. In the absence of a specific permit numeric ammonia limitation, an estimated value calculated to avoid toxicity has been used to set the treatment objective for ammonia since the mid-1990s. The estimated value, under 2.0 milligrams per liter (mg/l) total ammonia-nitrogen, is based upon maintaining an effluent concentration of less than 0.02 mg/l un-ionized ammonia under worst-case conditions (i.e., measure of acidity and alkalinity (ph) of 7.2 and temperature of 32 degrees Celsius ( C)) Pathogen Removal The AZPDES permits issued for the Roger Road WRF and Ina Road WRF include E. coli limits of 126 CFU/100 milliliters (ml) (four of seven samples collected per week) and 576 CFU/100 ml (singlesample maximum). The Aquifer Protection Permits (APP) for Roger Road WRF and Ina Road WRF include fecal coliform discharge limits of non-detect in four of seven samples collected per week and 23 CFU fecal coliform/100 ml or 15 CFU E. coli/100 ml (single sample maximum). Future expansions of the Roger Road WRF and Ina Road WRF may be subject to new facility BADCT requirements (refer to AAC R18-9-A211(B)(2)(b)), which apply to the following: Existing facilities discharging more than 5-mgd but less than or equal to 50-mgd that have undergone or will undergo a four percent increase in design flow Existing facilities discharging more than 0.5-mgd but less than or equal to 5-mgd that have undergone or will undergo a six percent increase in design flow Existing facilities discharging less than 0.5-mgd that have undergone or will undergo a ten percent increase in design flow For facilities discharging greater than 0.25 mgd, the BADCT requirements (set forth in AAC R18-9-B204 through B206) include fecal coliform/e. coli limits of no organisms detected in four of seven samples collected per week and a single sample maximum concentration of 23 cfu/100 ml for fecal coliform or 15 cfu/100 ml for E. coli bacteria Salinity Salinity, as measured by total dissolved solids (TDS), is not directly regulated by permit but is a potential concern in meeting biomonitoring requirements and potential customer quality requirements. Indicator microorganisms used in biomonitoring are sensitive to TDS concentrations, and TDS at a concentration of 1100 mg/l have been identified as a cause of persistent effluent toxicity to Ceriodaphnia. End uses, 8-18

21 including irrigation, cooling, and indirect reuse (via recharge and recovery), may ultimately require a reduction in effluent TDS levels. TDS in wastewater originates from a number of sources, including the water supply, urban additions (for example, discharges from residential and commercial water softeners, residuals and brines from upstream water and wastewater treatment plants, and cooling tower blowdown), and farming additions. Several studies have recently been conducted or are in progress to characterize sources and impacts of salinity Contaminants of Concern Emerging contaminants of concern include N-nitrosodiumdimethylamine (NDMA); pharmaceuticals, hormones, and other organic wastewater contaminants; and unregulated contaminant monitoring rule (UCMR)-listed pollutants. NDMA is classified by EPA as a possible human carcinogen, and the current AZPDES permits for the Roger Road WRF and Ina Road WRF require that it be monitored in the effluent. A potential byproduct of chlorine disinfection, its generation is apparently enhanced by the presence of chloramines in the wastewater. Detection of NDMA in the effluent could drive changes in the disinfection process at the wastewater treatment facilities. The detection limit and resulting notification limit of this contaminant is very low; 20 nano-grams per liter (ng/l) in the state of California. Pharmaceuticals, hormones, and other organic contaminants are not currently regulated by permit at the wastewater treatment facilities but are of growing concern nationwide. While requirements for photodegradation and biodegradation of pharmaceuticals have yet to be investigated, studies on emerging contaminants are receiving funds to begin testing ultraviolet and ozone effectiveness in reducing contaminant levels. High levels of perchlorate can cause adverse health effects such as interference with thyroid function. As a result, it was added to the list of unregulated chemicals for which monitoring are required under the UCMR. Arizona s current advisory health based guidance level for perchlorate is set at 14 ppb. Another contaminant shown to have cancerous effects is Arsenic. The EPA has set the maximum contaminant level for arsenic at 10 ppb Water Reuse Considerations The average demand (year 2006) in the Tucson water reclaimed water distribution system was approximately 11 mgd. The future demands for reclaimed water are expected to significantly increase from the year 2006 averages. Peak demands are 2.3 times the average. Storage in the conveyance system is 15 million gallons plus storage at local golf course lakes. The system experiences both seasonal and daily demands. The peak seasonal demands are in June and July. The low demand is in the winter. Daily demands peak at night when wastewater flows at the plant are low, making system storage necessary. Additionally, there are several pinch points in the existing distribution system that limits the capacity of the pipelines to deliver flow. 8-19

22 Additional considerations include: Effluent from the Sweetwater pressure filter treatment plant is blended with the recovered water from the recharge basin to achieve the Class A reclaimed water rating. There is no regulatory requirement for a minimum volume of discharge to the Santa Cruz River at Roger Road WRF. Effluent water will be made available to Tucson Water for their reclaimed water service system at the future WRC, Ina Road WRF and Randolph Park WRF. The plan allows for approximately 30-mgd at the WRC and approximately 20 mgd at Ina Road WRF based on allocated effluent water shares in the year The 3-mgd effluent from Randolph Park WRF is also available for reclaimed water use. Up to 7- mgd could be made available for discharge into the Santa Cruz River at the New WRC at Roger Road site. This would require that up to at least 5-mgd (existing plan) of the Ina Road WRF effluent be transferred to the Roger Road WRF site via a pumping station/force main system. The balance of the Ina Road WRF effluent beyond reuse needs provided directly from the Ina Road WRF will be discharged into the Santa Cruz River. Based on the project s objective to meet ADEQ regulatory requirements for future wastewater treatment, the New WRC at Roger Road and Ina Road WRF will also produce Class B+ reclaimed water. The water reuse purveyor will construct the necessary additional treatment necessary to meet its requirements and those of the water reuse permit. After completion of the work on the New WRC at Roger Road and the Ina Road WRF, reclaimed water quality will consistently meet B+ standard, but will produce near Class A+ quality reclaimed water. The difference between Class B+ and Class A+ is the inclusion of a very expensive filtration system that is not required by the receiving stream quality standards. Section 5 summarizes the reclaimed water standards based on the Arizona Administrative Code. The main goal of these projects is to meet ADEQ ammonia and nitrogen removal regulations and a secondary benefit is the ability to improve the reclaimed water quality. 8.6 Estimated Future Biosolids Production Through development of wastewater projections and treatment alternatives analysis associated with these projects, future biosolids production rates have been estimated for the Roger Road WRF and Ina Road WRF. The liquid stream treatment alternatives are impacted by recycles from the solids treatment processes, particularly from solids thickening and post stabilization thickening or dewatering. The type of solids stabilization utilized greatly impacts the constituents in the recycle streams, such as ammonia and phosphorus. Mass balances have been developed for the facilities to account for these recycle streams. Pima County will continue to utilize anaerobic digestion for solids stabilization of sludge streams from the Ina Road and Roger Road plants. It is recommended that a central biosolids processing facility be located at Ina Road WRF and the digestion facilities at Roger Road WRF be decommissioned. Centralization of solids handling and treatment is cost effective, particularly if Class A biosolids are desired in the future. Thus, a centralized biosolids processing facility serves as the starting point for development of biosolids processing alternatives. Roger Road WRF solids would be handled as follows: primary sludge (if primary tanks are provided) would be transferred to Ina Road WRF in the influent sewer, and waste activated sludge would be thickened to 3 percent solids at Roger Road WRF and then pumped to digestion at Ina Road WRF. 8-20

23 The County currently produces Class B biosolids at the Ina Road WRF and Roger Road WRF. This product is and is expected to remain consistent with land application into the future. The cost of producing Class A biosolids is considerably higher in capital investment as well as operation and maintenance costs regardless of the Class A process utilized. For example, Temperature Phased Anaerobic Digestion (TPAD) will require significant additional digesters, heating equipment, and heat exchangers to meet the Class A requirements. The need for Class A biosolids in the current regulatory and public environment is not clear. Special considerations have been made to make a plan such that future Class A facilities could be added on to the treatment trains. Thus, it is recommended that the County continue to produce Class B biosolids using consolidated mesophilic digestion facilities at Ina Road WRF. This stabilization process will provide digester gas for use at the plant. Additionally, TPAD, heat drying, or possibly the Cambi process could be added in the future to produce Class A biosolids if necessary. An arrangement has been determined for the required Class A TPAD facilities on the Ina Road WRF site based on the conceptual sizing performed in this chapter. Finally, the centrifuges should be designed to operate in either a thickening or dewatering mode that will permit the use of landfilling as a backup or contingency plan for biosolids handling Water Reclamation Campus Biosolids Decommission existing gravity thickeners and dissolved air flotation thickeners Provide waste activated sludge gravity belt thickening facilities with 4 gravity belt thickeners to produce a minimum of 3 percent solids Decommission existing digesters Improve transfer pump station facilities to transfer 3 percent waste activated sludge to Ina Road WRF through the existing transfer force main Consider providing redundancy to the single sludge force main through construction of a parallel force main Ina Road WRF Biosolids Expand existing gravity thickening facilities for primary sludge at the same size as existing for a total of 4 gravity thickeners to produce 5 percent solids. (If no thickening is provided at WRC, 6 gravity thickeners would be required.) Provide waste activated sludge gravity belt thickening facilities with 3 gravity belt thickeners to produce a minimum of 5 percent solids. (If no thickening is provided at Roger Road WRF, 6 gravity belt thickeners would be required.) Expand existing mesophilic digestion capacity with 6 additional digesters at the same size as existing Expand centrifuge facility to have 6 units (for 5 days per week operation) or 4 units (for 7 days per week operation) that can be operated to produce either thickened or dewatered solids Replace and expand centrate and cake pumping systems at the centrifuge facility Make provisions for struvite control in design of facilities with glass lined piping and possible chemical feed systems 8-21

24 If 5 days per week operation is desired for dewatering, provide digested sludge storage upstream of centrifuges Provide thickened/dewatered solids storage with storage capacity to hold 10 days of solids production Replace existing solids transfer station Additional digesters may be required if the biosolids market study determines Southlands WRF biosolids be treated at Ina Road WRF s biosolids processing facility. The market study should determine the extent (number of digesters, dewatering process, etc.) processing improvement requirements are to be made 8.7 Design Phases Construction occurring at the two facilities will be phased to meet regulatory compliance and to match population growth within the service areas. Project elements are listed in preferential order. Instrumentation and Control for the WRC is assumed to be included with the Ina Road Instrumentation and Control contracts. Wastewater service will continue throughout the entire construction process and following construction for all neighboring areas. One of the main reasons these projects have been recommended is to accommodate population growth within the service area. Wastewater service not located within the service area or privately owned should not be affected by the projects. Wastewater in the service area should be self-contained and treated by means of the conveyance system and the treatment plants in the area New Water Reclamation Campus at Roger Road For the new WRC at Roger Road, construction will allow the site to treat 32-mgd using Bardenpho treatment by the year Phase 1: Engineering, permitting and procurement services for Phases 2 and 5 to begin 2007/08 and be completed by Project Delivery: Professional Services Procurement Phase 2: Facilities to be under construction by 2011 and completed by 2015 are: Incoming Power service/standby power generation Site preparation (temporary administration building) Headworks 32-mgd Bardenpho treatment (includes clarifiers, blowers/mixers) Solids thickening/pumping Disinfection facilities Administration/control building Project Delivery: Construction Manager at Risk (CMAR) or Design/Build (D/B) Phase 3: Engineering, permitting and procurement services for Phase 4 to begin in 2014 and be completed by 2015 Project Delivery: Professional Services Procurement Phase 4: Facilities to be under construction by 2015 and completed by 2017 are: 8-22

25 Existing Roger Road WRF demolition Project Delivery: D/B or Design-Bid-Build (D-B-B) Ina Road WRF Construction to bring the capacity of the plant to 50-mgd will be complete by Phase 1: Engineering, permitting and procurement services for Phases 2, 3, 4 and 7 to begin 2007/08 and be completed by Project Delivery: Professional Services Procurement Phase 2: Power facilities to be under construction by 2010 and completed by 2012 are: Power unification/biogas power generation Project Delivery: Construction Manager at Risk (CMAR) or Design/Build (D/B) or (biogas power could be constructed under a public/private partnership arrangement) Phase 3: Wastewater reclamation facilities to be under construction by 2010 and completed by 2014 are: Site preparation Primary clarifier Bardenpho treatment (including clarifiers, blowers/mixers) Disinfection facilities Demolish HPO and oxygen system Project Delivery: CMAR or D/B or D-B-B Phase 4: Biosolids facilities to be under construction by 2010 and completed by 2014 are: Mesophilic digestion (4 new, 4 existing) Gravity thickening (primary sludge) Gravity belt thickening (WAS sludge) Centrifuge dewatering Sludge storage Project Delivery: CMAR or D-B-B Phase 5: Engineering, architectural, permitting and procurement services for Phase 6 to begin 2007/08 and be completed by Project Delivery: Professional Services Procurement Phase 6: Support facilities to be under construction by 2010 and completed by 2012: Centralized laboratory Project Delivery: Design/Build (D/B) or Construction Manager at Risk (CMAR) Phase 7: Biosolids facilities to be under construction by 2017 and completed by 2020 to coincide with additional wastewater facilities at Roger Road WRF are: Additional mesophilic digester Additional centrifuge thickener Project Delivery: D/B or CMAR 8-23

26 Phase 8: Engineering, permitting and procurement services for Phase 9 to begin 2018/19 and be completed by Project Delivery: Professional Services Procurement Phase 9: Future biosolids facilities to be under construction after completion of system-wide biosolids management plan and 2020 are: Thermophilic digesters or heat drying or other (Class A) process Project Delivery: Design/Build/Operate (D/B/O) or D/B or CMAR or (could be constructed earlier under a public/private partnership arrangement) Project Timeline A project timeline is shown in Figure 8-4 and shows the approximately time and cost (in 2006 dollars) to construct the various recommended projects discussed within this report. 8-24

27 Figure 8-4 ROMP Project Timeline 8.8 Stormwater Plan Stormwater detention systems for the facilities at the Roger Road WRF and Ina Road WRF are required by Pima County Regional Flood Control District and must be maintained. The storm water plan must meet the Pima County Regional Flood Control District design requirements for onsite detention systems and upholds the philosophy of no off-site discharges of storm water. The storm water plans will be developed in conjunction with detailed designs for each facility and will address storm water issues both during construction and post-construction. The storm water detention system will be designed to hold a 100-year, two-hour rainfall event on site. The collection system will be designed to prevent storm water infiltration at the new WRC and Ina Road WRF. Stormwater onsite will be retained and all other diverted away from the WRC. Storm water discharges from the WRC site will be subject to AZPDES storm water permitting requirements. The flows will be addressed through the implementation of a Stormwater Pollution Prevention Plan (SWPPP). 8-25