Basis of Design. NID Regional Water Supply Project. Technical Memorandum. July Prepared for Nevada Irrigation District City of Lincoln

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1 NID Regional Water Supply Project Technical Memorandum Basis of Design July 2010 Prepared for Nevada Irrigation District City of Lincoln 3875 Atherton Road Rocklin, CA Prepared by TEL FAX

2 NID Regional Water Supply Project Technical Memorandum Basis of Design July 2010 Prepared for Nevada Irrigation District City of Lincoln Prepared by ECO:LOGIC

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4 Contents NID Regional Water Supply Project Technical Memorandum Basis of Design ES EXECUTIVE SUMMARY... 1 ES.1 Background...1 ES.2 Water Treatment Plant Processes...2 ES.3 Site Development...2 ES.4 Opinion of Probable Cost INTRODUCTION Background Purpose and Scope Project Overview Staffing requirements Regulatory Agencies Topographic Survey Geotechnical Investigation WATER TREATMENT PLANT PROCESS General Discussion Pretreatment Filtration Disinfection Treatment Chemicals, Handling and Storage Solids Handling and Disposal Treated Water Storage SITE DEVELOPMENT Site Overview Site Development Landscaping Maintenance Building Environmental Architectural Renderings STRUCTURAL/ARCHITECTURAL DESIGN CRITERIA Structural Design Criteria Architectural Criteria ELECTRICAL DESIGN CRITERIA Power System Supply Electrical Power Equipment Design Codes and References...80 NVID i Regional Water Supply Project

5 Basis of Design 6.0 INSTRUMENTATION AND SCADA SCADA System Overview System Reliability Instrumentation Modes of Operation Monitoring and Control Instrumentation Provisions for Remote Monitoring and Automatic Operation SCADA System Security Communications and Software OPINION OF PROBABLE COST General Discussion Opinion of Probable Capital Costs Opinion of Probable Operations and Maintenance costs...95 Tables Table ES-1 Preliminary Design Criteria...4 Table ES-2 Probable Cost of Phasing from 10 MGD to 40 MGD...8 Table 1 Preliminary Design Criteria - Rapid Mix Basins...21 Table 2 Preliminary Design Criteria - Flocculation Basins...23 Table 3 Preliminary Design Criteria - Sedimentation Basins...24 Table 4 Preliminary Design Criteria - Filters...25 Table 5 Preliminary Design Criteria - Filter Backwash System...28 Table 6 Preliminary Disinfection Design Criteria Secondary UV with Primary/Secondary Chlorination...30 Table 7 Aluminum Sulfate Feed System, Design Criteria...32 Table 8 Sodium Hypochlorite Design Criteria...33 Table 9 Carbon Dioxide Design Criteria...34 Table 10 Soda Ash Design Criteria...35 Table 11 Liquid Polymer Design Criteria...36 Table 12 NID Preliminary Solids Handling Facilities...39 Table 13 TWS Sizing Criteria...40 Table 14 Treated Water Demands...40 Table 15 TWS Volume Based on City of Lincoln and NID Criteria...41 Table 16 TWS Volume Based on CDPH Title 22 Criteria...41 Table 17 TWS Design Criteria...42 Table 18 Materials and Design Stresses...58 Table 19 Dead and Live Loads...59 Table 20 Administration/Operations Building...61 Table 21 Chemical Building...61 Table 22 Rapid Mix/Flocculation/Sedimentation Building...62 Table 23 Filtration Building...62 Table 24 Maintenance Building...63 Table 25 Blower Room Building...63 Table 26 UV Disinfection and Backwash Pump Building...64 Table 27 Preliminary WTP Electrical Loads...77 Table 28 WTP Electrical Loads...78 NVID ii Regional Water Supply Project

6 Basis of Design Table MGD (Buildout) NID WTP Opinion of Probable Capital Costs...87 Table 30 WTP Unit Price Assumptions...89 Table 31 Initial Facility Scope compared to 40 MGD Facility...91 Table MGD WTP Opinion of Probable Capital Costs...92 Table 33 Probable Cost of Phasing from 10 MGD to 40 MGD...94 Figures Figure ES-1 Site Plan...5 Figure ES-2 Southeast Aerial...6 Figure 1 Vicinity Map...12 Figure 2 WTP Parcels...13 Figure 3 Possible Water Supply Diversion Points...15 Figure 4 Process Flow Diagram...19 Figure 5 Hydraulic Profile...20 Figure 6 Flocculation/Sedimentation Basins...22 Figure 7 Filtration Facility Plan View...26 Figure 8 Filtration Facility Section View...27 Figure 9 Chemical Storage Facility...37 Figure 10 Site Plan...44 Figure 11 Southeast Aerial...49 Figure 12 Southwest Aerial...50 Figure 13 Northwest Aerial...51 Figure 14 North Perspective...52 Figure 15 Northeast Perspective...53 Figure 16 South Perspective...54 Figure 17 Southwest Perspective...55 Figure 18 Northwest Perspective...56 Figure 19 Option 1 Floor Plan...66 Figure 20 Option 1 N.E. Axonometric View...67 Figure 21 Option 1 Entry Perspective...68 Figure 22 Option 2 1 st Floor Plan...69 Figure 23 Option 2 2 nd Floor Plan...70 Figure 24 Option 2 S.E. Axonometric View...71 Figure 25 Option 2 N.E. Axonometric View...72 Figure 26 Option 2 Entry Perspective...73 Figure 27 Option 2 Entry Perspective...74 Appendices Appendix A Appendix B Appendix C Appendix D Regulatory Overview Disinfection Strategies Treatment Residuals and Solids Handling Alternatives Preliminary Chemical Treatment Process Selection NVID iii Regional Water Supply Project

7 NID Regional Water Supply Project Technical Memorandum Basis of Design Prepared For: Prepared By: Reviewed By: Nevada Irrigation District and City of Lincoln Dave Hunt, P.E. Mike Wilkin, P.E. Gerry LaBudde, P.E. Date: July 2010 ES EXECUTIVE SUMMARY ES.1 BACKGROUND To address the projected demand for treated water in the City of Lincoln (the City) and Nevada Irrigation District (NID), NID and the City joined cooperatively and selected ECO:LOGIC Engineering to perform a study to evaluate and select a site for a new regional water treatment plant (WTP) facility. The results were presented in the Lincoln Area Water Treatment Plant Planning and Site Study, by ECO:LOGIC, August 2005 (2005 Site Study). Subsequent to the 2005 Site Study, ECO:LOGIC was selected to prepare a planning and predesign study for the NID Regional Water Supply Project (Project). This study was commissioned by NID to further investigate the feasibility of the Project, and to recommend the location, size, and configuration of Project components. The purpose of the Planning and Predesign Study is to recommend feasible alternatives to the Project as a whole, as well as alternatives for individual Project components, and then incorporate these recommendations into a proposed Project description for use in the Draft Environmental Impact Report (Draft EIR). The purpose of this Technical Memorandum (TM) is to serve as the Basis of Design TM (BDTM) for the proposed WTP. This BDTM provides basic design criteria for the water treatment process, site development, architectural, structural, electrical and SCADA/instrumentation components. The design criteria and costs associated with the WTP are based on an initial capacity of 10 million gallons per day (MGD), with an ultimate buildout capacity of 40 MGD. NVID Regional Water Supply Project

8 ` Basis of Design ES.2 WATER TREATMENT PLANT PROCESSES Section 2.0 of the BDTM presents a summary of the fundamental plant process design elements, including pretreatment components, filtration, disinfection, chemical handling and storage, solids handling, and the treated water storage components. The proposed facility will be a conventional surface water treatment plant utilizing coagulant addition, rapid mix, flocculation, sedimentation, filtration and disinfection. The coagulant used for the predesign was alum, however, other polymer coagulants such as polyaluminum chloride could be utilized. Rapid mix units are conventional open basin type with variable speed, top mounted mixers. Flocculation basins utilize tapered mixing energy in four stages using vertical paddlewheel mixers. Disinfection will be accomplished using secondary ultraviolet (UV) irradiation with primary/secondary chlorination. Finished water will be stored in one of three partially buried, reinforced concrete storage tanks. Residuals from the sedimentation tanks and filter backwash will be sent to the gravity thickening clarifiers and ultimately dewatered using a series of onsite drying beds. Table ES-1 provides a summary of the preliminary WTP process design criteria. ES.3 SITE DEVELOPMENT Section 3.0 presents a summary of the treatment plant site development, including process and non-process facilities (operations and laboratory building, maintenance building, yard piping, and landscaping). The site plan is presented in Figure ES-1. The site plan was developed utilizing several design elements, primarily focusing on the following: Site topography Hydraulic profile requirements and utilization of gravity flow Provide a visually aesthetic and environmentally sensitive design Site optimization for initial 10 MGD construction and subsequent 40 MGD expansion/buildout Create a centrally located operations facility that is operator friendly Accessibility of the facilities via the primary access road Ease of chemical deliveries and unloading area accessibility Maintaining operation of the existing Valley View irrigation reservoir during construction NVID Regional Water Supply Project

9 ` Basis of Design Water will be delivered by gravity flow to the head of the plant via a new raw water pipeline. The pipeline will provide a high hydraulic head which may be utilized to generate hydroelectric power at the WTP site. The hydraulic head will be reduced at the point of delivery, either through the hydroelectric power generation process or pressure reducing valve(s) and water will flow by gravity through the treatment train (coagulation/flocculation, sedimentation, filtration,, UV and chlorine disinfection) and into the treated water storage (TWS) tank(s). All primary roads and high traffic areas of the treatment plant will be paved with asphalt concrete (AC) pavement. Secondary roads on site are crushed gravel or aggregate base, most notably around the relocated Valley View Reservoir, sludge drying beds, and the solids storage area. Figure ES-2 includes an aerial perspective architectural rendering of the WTP site. Multiple renderings from ground and aerial perspectives are included in Section 3.0. NVID Regional Water Supply Project

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12 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure ES-2 Southeast Aerial

13 ` Basis of Design ES.4 OPINION OF PROBABLE COST Section 7.0 presents the opinion of probable construction costs for the 40 MGD treatment facility, cost assumptions, notable cost impacts, the probable construction costs for a 10 MGD initial facility phase, and estimated operations and maintenance costs. It also presents a brief discussion for alternative treated water storage phasing that could be considered if initial capital funds are limited. All costs are planning level, based on the 10 percent facility design. Treatment facility costs and finished water storage facility costs are separated to demonstrate the cost of treatment versus storage. Land acquisition cost estimates are based on recent selling prices of other properties in the area and is presented for budgeting purposed only. During land acquisition negotiations, anticipated sometime after the completion of CEQA, fair market value of land will be determined based on appraisals A 25 percent contingency is included at this planning level estimate for the Project and can be reduced after more detailed design allows quantity and unit price estimates to be refined. Table ES-2 presents the opinion of probable cost for the initial 10 MGD phase, the phasing cost from 10 MGD to 40 MGD, and the 40 MGD buildout facility. The phasing cost from 10 MGD to 40 MGD is presented to compare the initial 10 MGD phase and with the estimated costs to construct the WTP to its buildout 40 MGD capacity. The actual costs will depend on the nature of future phasing of the WTP capacity (i.e. 10 MGD to 20 MGD, etc.) NVID Regional Water Supply Project

14 ` Basis of Design NID WTP Site Plan Reference Table ES-2 Probable Cost of Phasing from 10 MGD to 40 MGD (a) 1 Treatment Facility Project Component Probable 10 MGD Costs Probable Phasing Costs Probable 40 MGD Costs 1.1 Mobilization/Demobilization $1,650,000 $2,600,000 $4,250, Sitework $2,530,000 $1,020,000 $3,540, Process Components Site Piping $3,660,000 $740,000 $4,400,000 2 Chemical Building & Systems $2,090,000 $1,090,000 $3,180,000 3 Administration & Operations Facility $140,000 $1,000,000 $1,140,000 7 Maintenance Building $ - $680,000 $680, Screening & Washing Facility $490,000 $370,000 $860,000 4 Rapid Mix Facility $140,000 $420,000 $560,000 4 Flocculation Basin $600,000 $1,820,000 $2,420,000 4 Sedimentation Basin $870,000 $2,620,000 $3,490,000 6 Filtration Facility $2,330,000 $5,440,000 $7,770, UV Disinfection $1,360,000 $4,060,000 $5,420,000 8 Gravity Thickener Clarifiers $600,000 $1,200,000 $1,800, Solids Dewatering/Drying Bed Equipment $360,000 $1,100,000 $1,460, Backwash Supply Pump Station $590,000 $ - $590, Recycle Water Pump Station $310,000 $70,000 $380, Solids Pump Station $210,000 $50,000 $260,000 9 Decant Pump Station $110,000 $40,000 $150,000 Subtotal $18,040,000 $24,310,000 $42,350,000 Electrical/Instrumentation (25%) $4,510,000 $6,078,000 $10,588,000 Subtotal $22,550,000 $30,388,000 $52,938,000 Engineering, legal, administration, and CM (20%) $4,510,000 $6,078,000 $10,588,000 2 Finished Water Storage Subtotal $27,060,000 $36,466,000 $63,526,000 Contingency (25%) $6,765,000 $9,117,000 $15,882,000 Treatment Facility Subtotal $33,825,000 $45,583,000 $79,408, Finished Water Storage Tanks $7,200,000 $14,050,000 $21,250, Tank Site Work $1,600,000 $2,900,000 $4,500, Tank Site Piping $720,000 $950,000 $1,670,000 Subtotal $9,520,000 $17,900,000 $27,420,000 Engineering, legal, administration, and CM (20%) $1,904,000 $3,580,000 $5,484,000 Subtotal $11,424,000 $21,480,000 $32,904,000 Contingency (25%) $2,856,000 $5,370,000 $8,226,000 Finished Water Storage Subtotal $14,280,000 $26,850,000 $41,130,000 NVID Regional Water Supply Project

15 ` Basis of Design NID WTP Site Plan Reference 3 Land Acquisition (b) Project Component Probable 10 MGD Costs Probable Phasing Costs Probable 40 MGD Costs $35,000/acre $2,975,000 $ - $2,975,000 Subtotal $2,975,000 $ - $2,975,000 Land Acquisition Fee (3%) $90,000 $ - $90,000 Subtotal $3,065,000 $ - $3,065,000 Contingency (25%) $767,000 $ - $767,000 Land Acquisition Subtotal $3,832,000 $ - $3,832,000 FACILITY TOTAL $51,937,000 $72,433,000 $124,370,000 (a) ENR 20 Cities CCI = 8,800 (July 2010) (b) Land costs presented for planning purposes. Actual cost will be determined based on appraisals during negotiations. 1.0 INTRODUCTION This section provides information about the overall Project as it relates specifically to the background, purpose, and scope of the Basis of Design for the proposed WTP. This section also provides an overview of the major WTP components along with the anticipated operational and staffing requirements. 1.1 BACKGROUND To address the projected demand for treated water in the City of Lincoln (City) and within the Nevada Irrigation District (NID) service area, NID and the City joined in a cooperative study to identify a site for a new regional water treatment plant. prepared the initial engineering study for the water treatment plant site evaluation and selection. Robertson- Bryan, Inc. prepared an environmental constraints analysis to screen the various sites to identify potential constraints or fatal flaws that would prevent or jeopardize the construction of the facilities. The results were presented in the Lincoln Area Water Treatment Plant Planning and Site Study, by ECO:LOGIC, August 2005 (2005 Site Study). Subsequent to the 2005 Site Study, ECO:LOGIC was selected to prepare a planning and predesign study for the NID Regional Water Supply Project (Project). This study was commissioned by NID to further investigate the feasibility of the Project, and to recommend the location, size, and configuration of Project components. The purpose of the Planning and Predesign Study is to recommend feasible alternatives to the Project as a whole, as well as alternatives for individual Project components, and then incorporate these recommendations into a proposed Project Description for use in the Draft Environmental Impact Report (Draft EIR). NVID Regional Water Supply Project

16 ` Basis of Design The proposed WTP and related facilities will serve the portion of the City and its sphere of influence, within NID s service area, as well as unincorporated areas outside of the City but within NID s service area. The addition of the new water supply to the City, in conjunction with the City s groundwater well network, and the service from the Placer County Water Agency (PCWA) will make up the City s treated water supply through the planned buildout included in the General Plan, [City of Lincoln General Plan and Background Report, by Mintier and Associates and Matrix Design Group Inc. dated March 2008]. During the 2005 Site Study, it became apparent that phasing of improvements would be necessary to finance and implement the Project. The phasing strategy consists of constructing treatment and storage facilities in stages, and utilizing existing raw water infrastructure where possible to minimize initial Project costs. As water demand increases, additional infrastructure would be constructed and financed with connection charges to provide additional capacity. The purpose of the phasing plan is to provide an estimated schedule of incremental facility and capacity improvements to minimize the initial Project cost when the demands are low, without jeopardizing the facility s ability to provide a reliable, long-term water supply. 1.2 PURPOSE AND SCOPE The purpose of this Technical Memorandum (TM) is to serve as the Basis of Design TM (BDTM) for the Project. This BDTM provides basic design criteria for the water treatment processes, site development, architectural, structural, electrical, and supervisory control and data acquisition (SCADA)/instrumentation components. References used in preparation of the BDTM include technical memorandums (TM) prepared as part of the Project and includes: Water Quality Sampling Sites and Constituents, ECO:LOGIC, April 2008 Pre-Design Geotechnical Report, Walker Water Treatment Plant, Blackburn Consulting, May 2009 Pre-Design Geotechnical Report, Pipeline and Whisky Run Tunnel, Blackburn Consulting, May 2009 Water Treatment Process Screening, ECO:LOGIC, May 2009 Land Use and Water Demands - Revised, ECO:LOGIC, October 2009 Water Quality Evaluation, ECO:LOGIC, October 2009 Water Treatment Plant Siting, ECO:LOGIC, October 2009 Raw and Treated Water Pipelines Corridor Evaluation, ECO:LOGIC, January PROJECT OVERVIEW An overview of the major WTP components is included below. Detailed discussion of the facility is included in the following section. The facilities will be designed and constructed in phases. The initial phase will provide 10 MGD of treated water. As the service area grows, the project will be expanded up to 40 MGD at buildout. NVID Regional Water Supply Project

17 ` Basis of Design WTP Site The Water Treatment Plant Siting TM recommended the predesign of the treatment facilities should be based upon the Walker site and the portion of the two adjacent parcels below NID Valley View Canal. The Walker site is owned by the Walkers. The parcel is approximately 58.3 acres in area. A portion of two other parcels (west of the Valley View Canal), has also been included in the overall site to optimize the WTP layout. The additional parcels include about 17 acres of a 123 acre parcel owned by R. Delarosa and approximately nine acres of a 131 acre parcel owned by J. Magonigal. Use of the land associated with these parcels will require lot line adjustments. Figure 1 provides a vicinity map of the Project. Figure 2 shows the parcels and their assessor's parcel number (APN) associated with the WTP. NVID Regional Water Supply Project

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19 600' 800' 700' 800' 600' 700' 900' 900' 600' LITTLE BEN RD BURNETT RD GARDEN BAR RD 400' 400' 500' 700' 800' 600' INDIAN CREEK RD 400' 500' 600' N KILAGA SPRINGS RD 600' 800' 300' APN ' APN APN ' 400' 400' NO. KILAGA SPRINGS 300' KILAGA SPRINGS RD Legend WTP PARCELS (A) WTP FACILITIES LOCATION ,000 FIGURE 2 WTP PARCELS 300' p Scale Feet 1" = 1,000' COORDINATE SYSTEM: CALIFORNIA STATE PLANE, ZONE II, NAD83 HORIZONTAL, U.S. SURVEY FEET THIS MAP IS COMPILED FROM THE FOLLOWING SOURCES: -ECO:LOGIC ENGINEERING -PLACER COUNTY, CA 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: NOTE: A) PARCELS DIRECTLY IMPACTED BY WTP FACILITIES. SECTION INCLUDES A DESCRIPTION OF RECOMMENDED LAND REQUIREMENTS FOR FACILITIES. H:\Projects-Active\2007\NVID WTP Project\gis\mxd\WTP Figures/Figure 1-2_ mxd

20 ` Basis of Design Water Supply NID's Combie Reservoir is the proposed primary source of raw water to the facility, although the location of the diversion point(s) may vary depending on Project phasing related to raw water conveyance facilities and water quality impacts from activities within the watershed affecting some of the potential conveyance facilities. Possible diversion points for the primary raw water supply include: Combie Ophir Phase 1 Canal just down stream of the Bear River Siphon in the vicinity of Lake Valley Drive, Camp Far West Canal about one and half miles west of the canal s diversion point from Coon Creek, A proposed back-up supply diverted from the Whiskey Diggins Canal located directly adjacent to and accessed through Hidden Falls Regional Park about a half mile north of Godely Road. Figure 3 shows the location of Combie Reservoir and the possible diversion points Water Treatment Process The Water Treatment Process Screening TM identified and evaluated five surface water treatment process alternatives including; Conventional pretreatment followed by granular media filtration, Conventional pretreatment followed by membrane filtration, Actiflo followed by granular media filtration or membrane filtration, and Tricon conventional package plant. The results of the matrix evaluation used in the selection process recommended conventional pretreatment followed by granular media filtration. However, future advances in membrane technology may drive the decision to utilize micro/ultra filtration at the new facility in lieu of gravity media filtration. Based on this recommendation, the BDTM presents the conventional pretreatment process including rapid mix, coagulation/flocculation, and sedimentation, followed by granular dual media filtration (anthracite and sand). NVID Regional Water Supply Project

21 COMBIE NORTH AQUEDUCT Lake Combie ORR CREEK TURNOUT WQ SAMPLE LOCATION (VICINITY OF THE PHASE 2 TURNOUT) COON CREEK TURNOUT WQ SAMPLE LOCATION CAMP FAR WEST TURNOUT WQ SAMPLE LOCATION (VICINITY OF THE PHASE 1 TURNOUT) TREATMENT PLANT SITE VICINITY CAMP FAR WEST CANAL WHISKEY DIGGINS CANAL TURNOUT WQ SAMPLE LOCATION (VICINITY OF BACKUP WATER SUPPLY TURNOUT) WHISKEY DIGGINS CANAL DIVERSION WQ SAMPLE LOCATION (VICINITY OF BACKUP WATER SUPPLY TURNOUT AT WHISKEY DIGGINS DIVERSION) Rock Creek Lake H:\Projects-Active\2007\NVID WTP Project\gis\mxd\water_quality_sample_locations_ mxd Map Legend SUPPLY DIVERSION POINTS TREATMENT PLANT SITE VICINITY 2, ,000 4,000 Scale Feet COORDINATE SYSTEM: CALIFORNIA STATE PLANE, ZONE II, NAD83 HORIZONTAL, U.S. SURVEY FEET THIS MAP IS COMPILED FROM THE FOLLOWING SOURCES: -ECO:LOGIC ENGINEERING -USGS -BLM 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: " = 4,000' HIGHWAY 49 Wise Forebay FIGURE 3 POSSIBLE WATER SUPPLY DIVERSION POINTS

22 ` Basis of Design WTP Facilities The scope of this BDTM includes the discussion and evaluation of the following WTP facilities and processes: Flow measurement Preliminary screening facility Rapid mix Coagulation/flocculation Sedimentation Gravity mixed media filtration Chemical feed systems Solids thickening clarifiers Solids drying beds UV disinfection system Chlorine disinfection system Finished water storage Pump stations Backwash supply Recycled backwash and decant water Drying bed sump pumps Solids thickening pumps Administration/laboratory building Chemical building Filtration building Maintenance building Site Access Site work Relocated Valley View Reservoir Stormwater and process overflow facilities On-site septic system 1.4 STAFFING REQUIREMENTS The staffing requirement for the initial 10 MGD phase of the treatment facility is expected to be one operator onsite for eight hours per day, with additional operations and maintenance support staff from the NID operations pool as required. This assumes monitoring of the facility through NID SCADA system when normal shift operators are not present at the facility. During successive increases in plant capacity, the operational staffing requirements of the plant will increase incrementally with the increase in plant capacity. At 20 MGD of production, it is expected that the plant will require staffing 16 hours per day, with a full time day shift and swing shift operator, with additional maintenance staff as required, with SCADA monitoring in the off peak hours. At 40 MGD the assumption is that the plant will require two full time day shift operators, and one operator each for the swing and graveyard shift, plus additional part time maintenance staff. NVID Regional Water Supply Project

23 ` Basis of Design 1.5 REGULATORY AGENCIES The following regulatory agency requirements have been incorporated into this BDTM: California Department of Public Health Placer County (Public Works, Community Development, Building Department, etc.) California Regional Water Quality Control Board 1.6 TOPOGRAPHIC SURVEY Andregg Geomatics performed preliminary aerial mapping of the water treatment plant site for the Project. The aerial survey included two-foot contours and was used in the development of the site layout. 1.7 GEOTECHNICAL INVESTIGATION In May 2009, Blackburn Consulting (BCI) prepared a Pre-Design Geotechnical Report for the Walker WTP site. The purposes of the report were to (1) evaluate the geotechnical feasibility for the WTP, finished water storage reservoirs, and access roads, and (2) provide geotechnical criteria for the preliminary design. The geotechnical report is available for review at NID s office. 2.0 WATER TREATMENT PLANT PROCESS Presented in this section is a summary of the fundamental plant process design elements. A discussion covering pretreatment components, filtration, disinfection, chemical handling and storage, solids handling, and the treated water storage components of the WTP design is summarized in this section. 2.1 GENERAL DISCUSSION The proposed facility will be a conventional surface WTP utilizing coagulant addition, rapid mix, flocculation, sedimentation, filtration and disinfection. A flow diagram showing the sequence of the unit processes is shown in Figure 4. The predesign is based on the use of alum as the primary coagulant. However, the use of other aluminum based coagulants such as poly-aluminum chloride (PAC) could be used. Rapid mix units are conventional open basin type with variable speed, top mounted mixers. Flocculation basins utilize tapered mixing energy in four stages using vertical paddlewheel mixers. At buildout plant capacity of 40 MGD, there will be a total of four sedimentation basins (fitted with 55 vertical inclined plate settlers) each processing 10 MGD (3.6 gpm/ft2). Disinfection will be accomplished using secondary ultraviolet (UV) irradiation with primary/secondary chlorination. Finished water will be stored in one of three partially buried, reinforced concrete storage tanks. As can be seen in the process flow diagram (Figure 4), residuals from the sedimentation tanks and filter backwash will be sent to the gravity thickening clarifiers and ultimately dewatered using a series of onsite drying beds. NVID Regional Water Supply Project

24 ` Basis of Design A preliminary hydraulic profile of the proposed treatment plant and associated processes is presented in Figure 5. The hydraulic grade line is based on the 40 MGD buildout plant flow and was set to maximize the energy efficiency of the plant by avoiding pumping wherever possible. The plant will be gravity feed except for the residuals management, return water and filter backwashing processes where the flows will have to be pumped. Treatment chemicals for all the processes will be handled and stored in a separate onsite chemical storage facility. All associated lab work and process treatment monitoring will be in a separate onsite administration building. Other support buildings will include a maintenance shop, various pump station buildings, a screening facility and a blower room. A discussion of the buildings and their design can be found in Section 4.0. NVID Regional Water Supply Project

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27 ` Basis of Design 2.2 PRETREATMENT The pretreatment unit processes are rapid mix, flocculation and sedimentation. The design criteria for each unit process are summarized in the following subsections Rapid Mix Design Preliminary design criteria for the recommended rapid mix units are presented in Table 1. Four rapid mix basins fitted with vertical, top mounted, mechanical flash mixers are recommended. One unit will be sufficient for flows up to 10 MGD. The top mounting mixer will allow for the greatest degree of operational flexibility and allow easy access for servicing. Preliminary design layout for the rapid mix basin is shown in Figure 6. The raw water will enter from the bottom of the rapid mix basin and exit via an overflow weir directly into the flocculators or possibly into a short effluent channel. Coagulant will be added to the raw water near the inlet to the rapid mix basin. To improve mixing efficiency, adjustable stators can be installed in the middle of the mix basin walls, the need of which may be a function of flow rate. This will be determined during final design. Table 1 Preliminary Design Criteria - Rapid Mix Basins Parameter Units Design Criteria Rapid Mixer - Flash Mixer in open top basin Treatment Trains # 4 Flow per Train MGD 10 Basin Dimensions feet 7 x 7 x 10 Detention Time (Design Target) s 30 Velocity Gradient (Design Target) s Motor Size horsepower 20 (variable speed) Impellers - Two, 6-Blade Rushton Turbine NVID Regional Water Supply Project

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29 Basis of Design Flocculation Basin Design At buildout, the proposed flocculation basins will consist of a total of four 10 MGD treatment trains operating in parallel. A summary of the preliminary design criteria for the recommended flocculation basins is presented in Table 2. A diagram showing the preliminary layout of the flocculation basins is shown in Figure 6. Each train will be fitted with four sets (stages) of variable speed, vertical shaft, paddlewheel-type mixers. Mixing energy will decrease as the water progresses through the stages (i.e., tapered flocculation). To accommodate varying flows and water conditions, flocculation energy input (velocity gradient) within each stage can be adjusted by varying the motor speed and/or changing the type of paddles. Each stage is separated by a perforated baffle wall to minimize short circuiting and allow for uniform flow conditions. Table 2 Preliminary Design Criteria - Flocculation Basins Parameter Units Design Criteria Treatment Trains # 4 Flow per Train (Max) MGD 10 Basin Dimensions feet 24 x 50 x 18 Stages # 4 Detention Time (@10 MGD/train) minutes 20 Mixer Type - Mechanical Vertical Paddle Units Velocity Gradient per stage Stage 1 s Stage 2 s Stage 3 s Stage 4 s Motor Size (hp) Stage 1 total horsepower 8 Stage 2 total horsepower 4 Stage 3 total horsepower 2 Stage 4 total horsepower 1 NVID Regional Water Supply Project

30 Basis of Design Sedimentation Design Requirements As with the flocculation basin, the proposed sedimentation basin design will have a total of four 10 MGD treatment trains operating in parallel at buildout. A summary of the preliminary design criteria for the recommended sedimentation basins is presented in Table 3. A diagram showing the preliminary layout of the sedimentation basins was shown in Figure 6. At 10 MGD, the maximum detention time is approximately 30 minutes and the loading rate is approximately 3.9 gpm/ft 2. Each settling basin will be outfitted with 55 (vertical) inclined plate settlers. Phasing and buildout may change the number and placement of the plates. Solids will be removed either intermittently or continuously, depending on seasonal operational demands, by a vacuum sludge collector system at a daily average flow rate of approximately 75 gpm per basin. Table 3 Preliminary Design Criteria - Sedimentation Basins Parameter Units Design Criteria Treatment Trains # 4 Flow per Train (Max) MGD 10 Basin Dimensions feet 21 x 85 x 18 Detention Time (@ 10 MGD/train) minutes 30 Loading Rate gpm/ft² 4 Settling Equipment - 55º Vertically Inclined Plate Settlers Solids Collection - Vacuum Sludge Collector Solids Removal Flow Rate (design) gpm FILTRATION The design criteria for the filters and the filter backwash components are presented in this section. Conventional granular media filters are proposed. The design parameters are based on a dual media filter configuration. Dimensions and sizing of the filtration facilities are preliminary; filter configuration and media will need to be pilot tested to determine the final media depths and grain sizes Filter Design Criteria Preliminary design criteria for the recommended dual media filters are summarized in Table 4. Presented in Figure 7 is a preliminary plan view of the filter gallery and a section view is shown in Figure 8. The filter gallery will be slightly below grade with a daylight basement on the southern side to allow access to the filters for maintenance. To provide maximum operational flexibility the filters will be configured as constant high rate, effluent controlled filters. Effluent control will be achieved via flow control valves in the effluent line of each filter. Influent from the sedimentation basin weirs will be equally split between filters unit using a common flume and distribution troughs above the filters. Filtered water will be collected using an underdrain system with attached porous media support plates. Channels in the underdrain system provide flow paths for the filter effluent, backwash water, and air scouring. NVID Regional Water Supply Project

31 Basis of Design As indicated in Table 4, redundancy will be provided by providing one additional filter so that capacity can be maintained with one filter out of service at a time for backwash. Table 4 Preliminary Design Criteria - Filters Parameter Units Design Criteria Number of Filters at 10 MGD 3 N+1 Number of Filters at 40 MGD 9 N+1 Redundancy 1 N+1 Flow Rate (Target) gpm/ft² 5 Average Filter Run Time (Target) hours 24 Filter Dimensions feet 20 x 35 ft 2 /filter 695 Anthracite layer inches 18 Sand Layer inches 12 Filtration Facility Footprint (40 MGD) ft² 17,850 Filter Underdrains - 8 to 14 in. thick corrosion resistant, support block underdrain Porous Media Support Plate - 1 to 3 inch NVID Regional Water Supply Project

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34 Basis of Design Filter Backwash Components Design Criteria Preliminary design criteria for the backwash system and auxiliary cleaning system are presented in Table 5. The recommended backwash configuration is to use high capacity, low head pumps that will deliver water from the finished water storage tanks directly to the filter units for backwashing. The first few minutes of the backwash cycle will include a combination of air scour and backwash, while the remainder of the backwash cycle will be a high backwash rate only. The air blowers for the air scouring system will be housed in a separate sound insulated blower room due to the associated noise. This air scour system will incorporate a specially designed under drain system with an air piping manifold to deliver the air to the filters. This system will also require specially designed wash troughs with baffles located along the outside of the trough to minimize the amount of media that can be washed into the trough. The filter to waste and backwash waste will flow by gravity to the gravity thickening clarifiers, which will allow solids to settle out. The decant water from the clarifiers will then be recycled to the front of the plant. A pump station will transfer the decant water back to the head of the plant. The pump station will be sized to prevent the possibility of overflowing a clarifier when running the filter to waste. The backwashing system will also be designed to limit backwashing multiple filters simultaneously in order to prevent the possibility of overflowing a clarifier. Table 5 Preliminary Design Criteria - Filter Backwash System Parameter Units Design Criteria Pre-Backwash Flow Rate gpm/ft² 5 with air scour Backwash Flow Rate gpm/ft² 20 Backwash Cycle Time minutes hour Backwash Supply gallons 1,400,000 Total WTP Recycled Water % 5 Backwash Pump Station gpm 2 duty pumps, one stand-by pump at 6,950 each Filter to Waste flow (est.) gpm/ft² 5 Filter to Waste Duration (est.) minutes 15 Filter to Waste and Backwash Waste Effluent - Send filter to waste & backwash waste water to gravity thickening clarifiers Clarifier Decant Recycle Pump gpm 2 duty pumps, 1 stand-by pump at 3,500 each Gravity Thickening Clarifiers feet 60 Ø 16 Depth Auxiliary Cleaning System - An air scour system incorporated into the underdrain laterals Air Scour Flow Rate scfm/ft² 4 Blowers scfm One duty and one stand-by at 2,800 Blower Room ft² 900 NVID Regional Water Supply Project

35 Basis of Design Monitoring Requirements for the Filtration System The water treatment plant will comply with the monitoring and reporting requirements, treatment techniques, performance standards, and turbidity standards established by the federal Surface Water Treatment Rule (SWTR), the Enhanced SWTR, the Interim Enhanced SWTR (IESWTR), the Long Term 2 ESWTR (LT2ESWTR), and California s SWTR as defined in Title 22, Chapter 17 of the California Code of Regulations. The California SWTR contains similar requirements as the federal ESWTR. The ESWTR Rule dictates that surface water treatment plants using conventional filtration must perform continuous turbidity monitoring on each individual filter unit and monitor the combined filter effluent at least every four hours. The maximum turbidity limit is 1 nephelometric turbidity unit (NTU) and the maximum average is 0.3 NTU for the monthly 95 th percentile. This will require turbidity monitors on each of the filter unit effluent lines and the combined filter effluent line. The IESWTR also states that filtered systems must physically remove 99 percent (2-log) of Cryptosporidium. Grab samples for Cryptosporidium and Giardia are to be taken at both the raw water influent of the treatment plant and effluent line of the filters. The water being recycled to the front of the plant will need to be monitored to ensure that it meets the requirements in the California Cryptosporidium Action Plan that states recycled water must have a turbidity of less than 2 NTU. The Filter Backwash Recycling Rule (FBR) established by the EPA states that recycled filter backwash water, sludge thickener supernatant, and liquids from dewatering processes must be returned through the systems existing treatment processes (coagulation, flocculation, sedimentation, and filtration). All backwash water, filter to waste, sludge thickener supernatant, and water from the dewatering process will be returned to the head of the water treatment plant, which satisfies the backwash recycling rule. A detailed overview of current and future regulations that will affect the design and operation of the new WTP is presented in Appendix A. 2.4 DISINFECTION Based on a detailed evaluation of all potential disinfection strategies, the strategy selected was secondary UV disinfection with primary/secondary chlorination. This strategy will not only meet the requirements of the current SWTR, but also the anticipated Cryptosporidium inactivation requirements of the LT2ESWTR. For the purpose of developing the maximum footprint, the design is based upon Bin 4 classification for Cryptosporidium removal/inactivation pursuant to the LT2ESWTR which represents the worst case from a treatment process perspective. Chlorination alone will not satisfy the log inactivation requirements for Cryptosporidium. UV is very effective in meeting Giardia and Cryptosporidium inactivation requirements and has lower capital costs, operation and maintenance costs (O&M), and 20-year present worth costs than NVID Regional Water Supply Project

36 Basis of Design other alternatives (i.e., ozone). Furthermore, UV has a much smaller footprint (than ozone) and does not form disinfection by-products (DBP). Design criteria for the recommended disinfection strategy are presented in Table 6. For the full disinfection selection process, refer to Appendix B. Table 6 Preliminary Disinfection Design Criteria Secondary UV with Primary/Secondary Chlorination UV Design Criteria (@ 10 MGD) Units Design Criteria Target log inactivation for Giardia Log 1.5 Target log inactivation for Cryptosporidium Log 2.5 UV dose required for Cryptosporidium inactivation (a) mj/cm Chlorination Design Criteria (@ 10 MGD) Units Design Criteria Target log inactivation for virus Log 3.0 Contact time (CT) required (ph=8.5, Temp.=5ºC) mg-min/l 6 Baffling Factor in Finished Water Storage Tank mg/l residual minutes 8 Hydraulic Detention Time minutes 16 Volume Required for CT gallons 100,000 Chlorine Dose, maximum Pretreatment mg/l 1.0 Post Filtration mg/l 1.5 Chlorine 10 MGD ppd 200 (a) Actual applied UV dose will be based on validation testing as required by the LT2ESWTR. 2.5 TREATMENT CHEMICALS, HANDLING AND STORAGE The regional WTP includes chemical storage and feed systems for aluminum sulfate (alum), carbon dioxide, polymers (anionic, cationic and non-ionic), sodium hypochlorite and soda ash. This section presents results from the preliminary chemical treatment analysis technical memorandum located in Appendix D. The design of the chemical feed, storage and handling systems is based on the following criteria: The final chemical storage tanks will be sized for 30 days of storage at 40 MGD (maximum flow). Each of the chemical storage rooms will require 110 percent liquid containment of the largest chemical tank per the California Building Code. NVID Regional Water Supply Project

37 Basis of Design Single wall, full drain, high-density polyethylene (HDPE) chemical storage tanks are recommended to store the liquid chemicals, such as sodium hypochlorite and aluminum. Polymers are typically delivered and stored in 4 x4 x4 square plastic totes. Totes will act as the storage tanks in the polymer delivery system and will be replaced with new full totes as needed. Chemical feed lines will be housed in polyvinyl chloride (PVC) conduit to provide leak containment from storage to the point of chemical injection. Emergency eyewashes and showers will be provided in easily accessible locations in the chemical building as well as at the chemical unloading station. Chemical fill stations will be equipped with tank level indicators in order to prevent the overfilling of any tank. Tanks will also be equipped with high/low level alarm systems, plus high-high overflow alarms for safety. A standby backup pump should be present for each chemical pumping system regardless of the type of chemical feed pump selected. The metering pump systems will have the capability to be both manually and remotely controlled. Chemical storage is sized for monthly delivery. The storage rooms will be clearly designated with chemical placards for ease of delivery. Roll-up doors will be provided for each chemical room for ease of delivery and safety purposes. Chemical fill lines will be provided at each individual chemical storage area roll up door, and fill lines will be located inside the containment area. The entire chemical unloading area will be equipped with secondary spill containment located outside the chemical building for safety during unloading. NVID Regional Water Supply Project

38 Basis of Design Aluminum Sulfate A single coagulant feed system is planned for the WTP using aluminum sulfate (alum) as the primary coagulant. Alum was selected over polyaluminum chloride as it has the greatest expected dose resulting in the largest required chemical storage and building footprints. If operations desire to use other coagulants, there will be ample storage available. The design alum dose of 20 mg/l corresponds to a daily consumption of approximately 1,200 gallons at a plant capacity of 40 MGD. The design criteria associated with the alum storage and feed systems are shown in Table 7. Table 7 Aluminum Sulfate Feed System, Design Criteria Parameter Units Design Criteria Plant Flow MGD 40 Chemical Properties: Chemical State - Liquid Effective Density lbs/gal 5.60 Solution Strength % 48.5 Chemical Dose mg/l days Storage Requirement: Alum Volume (20 mg/l, 40 MGD) gallons 36,000 Storage Tanks # 4 Tank Capacity gallons 10,300 Total Tank Capacity gallons 41,200 Tank Diameter feet 12 Tank Height feet 14.5 Chemical Delivery System: Feed Pump type Diaphragm Number of Pumps 2 2 (duty/standby) Chemical Feed Rate gph SODIUM HYPOCHLORITE Chlorination with sodium hypochlorite is planned for preoxidation, primary/secondary disinfection and to achieve a chlorine residual in the distribution system. Chlorination is planned at the following locations (chlorine dosages are assumed maximums and are used for facility sizing): Preoxidation (headworks) : 0.5 mg/l, maximum Pretreatment: 0.5 mg/l, maximum NVID Regional Water Supply Project

39 Basis of Design Post Filtration: 1.5 mg/l, maximum (minimum free residual of 0.2 mg/l in distribution system) Backwash Water (1.0 mg/l) The maximum expected process water chlorine dose is 2.5 mg/l, which corresponds to a daily chlorine consumption of approximately 1,000 gallons per day at a buildout capacity of 40 MGD. Chlorinated backwash water ( 1 mg/l free chlorine) can be used to assist in the removal or prevention of polymer accumulation or mudball formation. The hypochlorite storage tanks and chemical feed equipment will be contained in the chemical building. Four polyethylene storage tanks containing a 30 day supply of hypochlorite (29,000 gallons) are planned. Four pairs of chemical metering pumps (duty and standby pumps) are planned to supply chemical to each of the above listed feed locations. Design criteria for the sodium hypochlorite feed, storage and handling are summarized in Table 8. Chemical Properties: Table 8 Sodium Hypochlorite Design Criteria Parameter Units Design Criteria Chemical State - Liquid Available Chlorine lbs/gal 1.0 Solution Strength % 12.5 Chemical Dose mg/l days Storage Tank Requirement: Hypochlorite Volume (2.5 mg/l, 40 MGD) gallons 29,000 Tanks # 4 Tank Capacity gallons 8,100 Total Tank Capacity gallons 32,400 Tank Diameter feet 12 Tank Height feet 12 Chemical Delivery System: Plant Flow MGD 40 Feed Pump type Diaphragm Number of Pumps 8 2 per injection location (duty & standby) Chemical Feed Rate gph NVID Regional Water Supply Project

40 Basis of Design Carbon Dioxide Carbon dioxide (CO 2 ) will be used for its ability to lower ph of the process water. For effective coagulation and disinfection processes, ph ranges of and should be maintained, respectively. The recommended CO 2 storage and feed system is a manufacturer supplied skid mounted outdoor unit consisting of a liquid CO 2 storage cylinder and a pressurized CO 2 feed system which forces CO 2 gas into a carrier water solution under high pressure which is then injected into the process water. An online ph monitor immediately downstream of the chemical feed system allows precise control of the treated water ph. For design purposes, a CO 2 dose of 10 mg/l was used. The liquid CO 2 will be delivered to the plant in tank trucks. The CO 2 solution will be applied prior to the rapid mix basin. Design information for the CO 2 storage and feed is summarized in Table 9. Chemical Properties: Table 9 Carbon Dioxide Design Criteria Parameter Units Design Criteria Chemical State - Gas (injected), Liquid (stored) Effective Density scf/lb 8.74 Chemical Dose mg/l days Storage Tank Requirement: CO 2 Volume (10 mg/l, 40 MGD) lbs 101,000 Tank # 1 Total Tank Capacity tons 50 Tank Diameter feet 9 Tank Length feet 57 Chemical Delivery System: Carbon Dioxide Gas Feed System Flow lbs/hr Carbonic Acid Solution Feed System type Centrifugal Number of Pumps # 2 (duty/standby) Solution Feed Rate gpm Soda Ash Sodium carbonate (soda ash) will be used to increase process water ph and alkalinity to maintain target coagulation process ph and for corrosion control (copper and lead). A 5 mg/l pretreatment dosage and 15 mg/l corrosion control dose are used for the chemical storage and feed system design equating to a daily consumption of 6,700 pounds (dry soda ash) and a 30 day storage requirement of 3,654 cubic feet. The dry soda ash will be pneumatically transferred into the storage silos located in an isolated room within the chemical building. For a detailed NVID Regional Water Supply Project

41 Basis of Design explanation of the dry chemical feed system refer to Appendix D. Design information for the soda ash storage and feed is summarized in Table 10. Chemical Properties: Table 10 Soda Ash Design Criteria Parameter Units Design Criteria Delivered Chemical State - Dry Powder Bulk Density lbs/ft 3 55 Effective Density (10% soln) lbs/gal 1.10 Solution Strength % 10 Chemical Dose mg/l days Storage Requirement: Dry Soda Ash (20 mg/l, 40 MGD) ft 3 3,640 Dry Storage Bins Tanks # 4 Silo Capacity ft 3 1,093 Total Silo Capacity ft 3 4,372 Silo Diameter feet 10 Silo Height feet 22 Screw Feeders # 4 Screw Conveyor # 1 Bucket Elevator - 20 lift, 280 cu. ft. per hr. Surge Hopper - 1 unit, 30 cu. ft. Volumetric Screw Feeder - 1 hp, 1800 rpm Slurry Mixing Tank # 1 Tank Capacity gallons 800 Tank Diameter feet 4.5 Tank Height feet 7 Solution Holding Tank # 1 Tank Capacity gallons 6,100 Tank Diameter feet 10 Tank Height feet 13 Chemical Delivery System: Dry Chemical Feed to Slurry Mixer #, pump type 1, Volumetric Slurry Transfer Pumps to Holding Tank #, pump type 2, Centrifugal Slurry Transfer Rate gph Solution Feed Pumps to Injection #, type 4, Positive Displacement Soda Ash Feed Rate gph NVID Regional Water Supply Project

42 Basis of Design Liquid Polymers Liquid polymers are recommended to increase the effectiveness of coagulation and flocculation, increase filterability and reduce sludge volume and overall operating costs. Separate liquid polymers feed systems are included for coagulant aid, flocculant aid, filter aid and solids thickening aid. Polymer storage and feed system equipment will be contained in a separate room within the chemical building. Polymers will be delivered in totes and an interim polymer storage area is planned adjacent to the polymer room that is accessible by forklift. A polymer feed system will include chemical metering pumps (one duty, one standby), dilution water, a low speed mechanical mixer (400 rpm or less) and associated piping and fittings. Design information for the polymer storage and handling is summarized in Table 11. Chemical Properties: Table 11 Liquid Polymer Design Criteria Parameter Units Design Criteria Chemical State - Liquid Effective Density lbs/gal 8.4 Coagulant aid (Typically Cationic) mg/l Flocculant aid (Typically Anionic) mg/l Filter aid (Typically Nonionic) mg/l Solids Thickening (Cationic or Anionic) mg/l days Storage Requirement: Storage Totes # 7 Tote Capacity gallons 275 Total Tote Capacity gallons 1,925 Tote Length and Width feet 4 Tote Height feet-inches 2-6 Chemical Delivery System: Feed Pump type Diaphragm Number of Pumps # 10, (2 per use) (duty/standby) Flow gph Chemical Building Layout The preliminary chemical building layout is presented in Figure 9. The figure displays the chemical building layouts for the 10 MGD and 40 MGD phases. The tank sizes shown in Figure 9 correspond to the sizes discussed in this section. NVID Regional Water Supply Project

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44 Basis of Design 2.6 SOLIDS HANDLING AND DISPOSAL Solids generated by the water treatment processes will be processed through the use of gravity thickening clarifiers and solids drying beds. Appendix C, Treatment Residuals and Solids Handling Alternatives, presents the analysis detailing the solids handling and disposal analysis Recycled Water Each of the treatment and monitoring processes throughout the treatment plant create a process waste stream. These waste streams will be conveyed to the solids collection and processing facilities. The waste streams include sludge from the sedimentation basins, backwash (BW) water from the filters, filter to waste water (FTW), decant water from the sludge drying ponds, and the drains from the various monitoring and sampling stations. Waste streams will be clarified to remove suspended solids, the thickened solids will be sent to solids dewatering and drying facilities, and the clarified process water will be returned to the head of the treatment plant for retreatment. The California Cryptosporidium Action Plan requires an operational goal for all clarified solids process stream effluent to achieve 2 NTU or less, and the recycled water should be less than ten percent of the raw water flow. The FTW and process monitoring streams will be handled separately from the solids process streams due to their already low turbidity and differing treatment requirements before recycling Solids Production Although the plant is expected to expand in phases, with an initial capacity of 10 MGD, the site plan and treatment residuals planning study needs to account for the full 40 MGD capacity. Based on the evaluation of the technologies available to best suit the site hydraulics and topography, and based on input received during meetings with NID's staff, solids thickening clarifiers with mixed dewatering and drying beds is the recommended alternative for the WTP. It is also recommended that NID incorporate a designated alternate solids drying/storage area at the site for flexibility at buildout. This configuration has a compact footprint, fits well on the site, minimizes the amount of required site work, and has a low present worth value. A summary of the preliminary sizing for the solids dewatering facilities is displayed in Table 12. NVID Regional Water Supply Project

45 Basis of Design Gravity Thickening Clarifiers Table 12 NID Preliminary Solids Handling Facilities Parameter Units Design Criteria Dimensions feet 60 diameter 16 Depth Number # 3 Effluent Solids Concentration % 2-4 Drying Beds Dimensions ft² 57,000 Number # 2 Final Solids Concentration % 35 Solids Storage Area Dimensions ft² 42,000 Number # 1 Final Solids Concentration % Solids Disposal Solids disposal can typically represent a substantial portion of the solids handling operating costs. Water treatment solids are not high in nutrients, unlike biosolids, so are not typically used for land application disposal. The alum salts content may potentially have adverse affects on some plants and water sources. Trucking the solids to a nearby landfill is recommended as the best option for disposing of the dewatered solids. The costs presented in Appendix C are based on disposal of solids at the Western Regional Landfill located in Lincoln, approximately 35 miles round trip from the WTP site. 2.7 TREATED WATER STORAGE Treated water storage (TWS) will be provided onsite to provide for equalization storage, emergency reserve, fire reserve and contact time for disinfection. The TWS analysis is based on an initial plant capacity of 10 MGD with a buildout capacity of 40 MGD. TWS requirements were developed based on three sets of criteria: CDPH Title 22, Chapter 16 (March 2008) City of Lincoln General Plan Update Water System Constraints Analysis (2006) NID Treated Water Master Plan Assumptions Update (May 1995) Table 13 below summarizes the TWS sizing criteria. The City of Lincoln TWS requirements includes equalizing, emergency and fire reserve, while the NID requirement breaks these components down into separate criteria. The CDPH requirement is in addition to the fire reserve storage requirement. TWS sizing criteria is based on estimated maximum day demands (MDD) for the Project. NVID Regional Water Supply Project

46 Basis of Design City of Lincoln (a) NID (b) Equalizing Storage Emergency Reserve Fire Reserve Criteria CDPH Title 22 Chapter 16 (c) Table 13 TWS Sizing Criteria TWS Requirement 100% of MDD 25% of MDD 75% of MDD Highest fire flow x duration 4 hours PHD (a) Table 6 Water System Constraints Analysis (2006) Lincoln General Plan Update (b) Table 3 NID Treated Water Master Plan Assumptions Update (1995) (c) CCR Title 22, Chapter New and Existing Source Capacity Treated water demands used for sizing TWS facilities are shown in Table 14 and are based on the Land Use and Water Demands TM (ECO:LOGIC, September 2008) Table 7 Estimate of Water Demands within the Study Area. Peak hour demand (PHD) factors used in the calculation include 1.6xMDD for the City of Lincoln service territory and 2.0xMDD for the NID soft service area. Table 14 Treated Water Demands MDD, MGD PHD, MGD 10 MGD 40 MGD 10 MGD 40 MGD City of Lincoln NID Total Demands TWS requirements were calculated using all three sizing criteria. The fire flow component used in the calculation includes a commercial/industrial volume of 960,000 gallons (4,000 gpm for 4 hours) and an average single family residential (SFR) fire flow volume of 180,000 gallons (1,500 gpm for 2 hours) for the City of Lincoln service area, and a SFR fire flow only for the NID service territory. The NID soft service area will only have residential construction and the City of Lincoln will include both residential and commercial/industrial fire flows. Storage volume required for disinfection contact time is based on UV disinfection for Giardia and Cryptosporidium inactivation and a 3-log virus inactivation by chlorine in the TWS tank(s). The required CT to meet 3-log inactivation of virus by chlorine is 6 mg-min/l at a lowest estimated temperature of 5 C and a ph of 8.5. The estimated baffling factor for the TWS tanks is 0.50 (to include interior baffling to direct flow in a spiral path). Based on these criteria the following storage volumes are necessary to meet the virus inactivation requirements: 100,000 gallons at 10 MGD plant capacity 400,000 gallons at 40 MGD plant capacity NVID Regional Water Supply Project

47 Basis of Design The contact time requirements discussed above are based on 1.5-log Giardia and 2.5-log Cryptosporidium inactivation by UV (as required by the LT2ESWTR Bin 4 classification) and 3- log virus inactivation by chlorine. If only 2-log removal of Cryptosporidium was required under the LT2ESWTR, which would be achieved through conventional treatment alone, then the disinfection strategy could include chlorination only for virus and Giardia inactivation. Disinfection contact time would then be required for 1.5-log inactivation of Giardia which would require a storage volume of 2.3 MG at 10 MGD capacity and 9 MG at 37.2 MGD capacity (see Appendix B, Disinfection Strategies). Table 15 summarizes the TWS requirements based on the City of Lincoln and NID criteria discussed above. For comparison, Table 16 provides the TWS requirement based on the CDPH requirements. City of Lincoln Table 15 TWS Volume Based on City of Lincoln and NID Criteria Criteria 10 MGD 40 MGD 100% of MDD NID (service area outside of City of Lincoln) Subtotal Equalizing Storage Emergency Reserve Fire Reserve (SFR fire flow requirement) Subtotal Disinfection CT Storage Total TWS MGD Table 16 TWS Volume Based on CDPH Title 22 Criteria Criteria TWS, MG PHD = hours 2.82 Fire Reserve (SFR + industrial/commercial fire flow) 1.14 Disinfection CT Storage MGD 10 MGD 4.1 PHD = hours 10.6 Fire Reserve (SFR + industrial/commercial fire flow) 1.14 Disinfection CT Storage 0.4 Total TWS 12.1 NVID Regional Water Supply Project

48 Basis of Design For the purpose of the Project predesign, the TWS requirements will be based on the City of Lincoln and NID criteria. The site plan has been developed to provide for three equally sized 12.6 MG tanks. The tanks would be 270-foot diameter with a 30 foot water depth. Table 17 provides the design criteria for the TWS tanks. Table 17 TWS Design Criteria Criteria 10 MGD 40 MGD Number of Tanks 1 3 Total Storage Capacity, MG Tank Diameter, feet Tank Height, feet Overflow Height, feet Tank Material Pre-stressed Concrete Pre-stressed Concrete Base Elevation, min., feet T 10 /T Baffled yes Yes 3.0 SITE DEVELOPMENT Presented in this section is a summary of the treatment plant site development, including site layout, excavation discussion, expansion phasing considerations, environmental impacts and restoration, maintenance building, and landscaping. 3.1 SITE OVERVIEW The proposed facility will be a conventional surface WTP with an initial capacity of 10 MGD, and a designated buildout capacity of 40 MGD. The preliminary site plan presents all of the major process and non-process structures and associated mechanical piping in Figure 10. The site development plan was developed utilizing several design elements, primarily focusing on the following: Site topography Hydraulic profile requirements and use of gravity flow Provide a visually aesthetic and environmentally sensitive design Site optimization for initial 10 MGD construction and subsequent 40 MGD expansion/buildout Creation of a centrally located operations facility that is operator friendly NVID Regional Water Supply Project

49 Basis of Design Accessibility of the facilities via the primary access road Ease of chemical deliveries and unloading area accessibility Maintaining operation of the existing Valley View irrigation reservoir during construction Raw water will be conveyed to the site via a pipeline under pressure. The pressure will be reduced at the point of delivery, either through the hydroelectric power generation process or pressure reducing valve(s) and water will flow by gravity through the pretreatment, filtration process, UV and chlorine disinfection, and into the TWS tank(s) as seen in Figure 10. Solids from the filtration process will be dried and stockpiled on site; dried solids will be hauled off site to landfill. All traveled surfaces within the treatment plant site will be constructed as gravel roads for the first phase of the WTP. The primary traffic routes will be paved with AC pavement during subsequent WTP phases. All Secondary roads on site are crushed gravel or aggregate base, most notably around the new Valley View Reservoir, sludge drying beds, and the solids storage area. NVID Regional Water Supply Project

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51 Basis of Design 3.2 SITE DEVELOPMENT Key factors considered during site development are summarized in this section Site Layout The preliminary site layout is shown in Figure 10 effectively utilized the existing grade topography to create a facility that achieves the goals set by the design elements as mentioned previously. The existing site topography provided the slope necessary for a gravity flow through the treatment process. The orientation of the various components of the facility allows the operators to view the facilities from the operations office including the main entrance to the WTP. In addition to the operator s ability to oversee the extent of the facility, a six foot chain link security fence with barbed wire will surround the entire facility and all building and treatment components will be designed to meet Department of Homeland Security requirements at the time of design. Examples of security measures are anticipated to include, site surveillance cameras, intrusion alarms for buildings and tanks, etc. Chemical deliveries and other WTP traffic will be accessed through the main entrance. The main access road is 20 feet wide with a 5 percent maximum slope, and a minimum centerline turning radius is 70 feet and will provide adequate maneuverability for safe access, including tractor trailers for bulk chemical deliveries. Deliveries will be made to the south side of the chemical building allowing the operators to observe the delivery activities while providing the ability to monitor the treatment process at the same time from the operations building. The orientation of the structures were selected to minimize environmental and visual impacts by minimizing tree removal, locating most structures to reduce their silhouette, and maintaining the integrity of the original landscape as best as possible. The predicted 100-year storm water flow for the WTP site, 36 cubic feet per second (cfs), was calculated using the Placer County Stormwater Design Manual standards. Rip-rap lined storm water ditches will channel water throughout the site into storm water detention basins. Detention basins have been added at four key locations on the site to capture sediments and mitigate peak flows, prevent erosion of existing and developed areas, and to prevent any concentrated increase in flow from the developed areas from leaving the site. Detention basins have been strategically located on the site to capture a 40 (62 cfs) MGD treatment overflow for thirty minutes from the raw water/pretreatment area, and a 40 MGD overflow for thirty minutes from the finished water storage tanks. The stormwater conveyance systems will be designed for the individual 40 MGD WTP overflow or storm event, and not coincidental flows of both events occurring simultaneously. NVID Regional Water Supply Project

52 Basis of Design Excavation The site excavation restrictions and requirements are based on a preliminary geotechnical report of the proposed WTP site. The geotechnical report findings are that the site is suitable for the design intent of the Project. The report details that exploratory excavations indicated that the area is variably rocky within 15 ft (average) of the surface. This area is characterized as generally rippable with a Caterpillar D9 dozer. Results from multiple seismic lines, which measure energy transmitted through the subsurface material and is correlated to the type of material present, indicates that a significant rock layer with seismic velocities greater than 7,000 feet per second is encountered beyond the 15 ft depth. The report concludes that rock with seismic velocities greater than 7,000 feet per second may require blasting. Overall excavation will generally be via dozer and excavator, assuming rocky material will preclude using scrapers. Results from excavation calculations approximate the volume of earth to be moved at approximately 400,000 cubic yards (yd 3 ). The majority of the excavation occurs at the finished water storage tank portion of the site. Most of the rock that may potentially be encountered is in this location due to the depth of cut required for the tank pads, the volume is estimated at approximately 80,000 yd 3. The following bullets detail some of the excavation design assumptions, criteria, and methods utilized to determine excavation volumes: All excess material will be placed on site to avoid the high costs associated with offsite disposal. It is assumed that all excess rock will be incorporated into mass fill, or crushed on site for rip-rap and/or gravel surfacing. Steepest allowable permanent cut slopes should be 1.5H:1V, reinforced cut slopes may go to 1H:1V, construction slopes will be limited to 3/4:1. Steepest allowable fill slopes should be 2H:1V, height limited to 20. The approach to calculating an estimated volume of rock utilized CAD Civil 3D grading tools in part with the Geotechnical report; specifically the seismic velocity lines discussed previously which identify the depths to the non-rippable rock Tank and Treatment Site Phasing Considerations The first phase of the proposed WTP will be 10 MGD. Due to this, several considerations must be evaluated to fully understand the constructability and costs associated with the excavations at the site. Below is a list of critical issues that may influence phasing plans and options for earthwork on the site. A combined site grading plan will be developed to balance the earthwork Earthwork for the treatment plant site with one TWS tank (13 MGD) nearly balance, but a significant volume of excess material will be produced when additional TWS tanks are added NVID Regional Water Supply Project

53 Basis of Design The development of the sludge drying area for the 40 MGD buildout provides an excess fill area on site to prevent expensive off-haul/disposal costs. The tank site potentially contains significant amounts of rock it is proposed to: Place the first TWS tank in the rockier area of the tank site now and doing the blasting during the first phase since future blasting could put the structural integrity of the existing TWS tanks at greater risk. Conduct more detailed subsurface exploration and characterization in the future to determine extent of rock in the treated water storage area Yard Piping Yard piping for the WTP is designed for 10 MGD expandable to 40 MGD see Figure 10. Initial 10 MGD primary piping excavation corridors will be large enough to accommodate future parallel piping. These corridors will be backfilled with select material to allow easier excavations for future expansions. Upfront planning for secondary piping to be constructed during future expansions will allow ample room for ease of excavation and installation. Final yard piping layouts will be performed during future design efforts. All yard piping is initially sized for 4-6 feet-per-second pipeline velocities at design flows. A single 66" pipeline will connect the finished water storage reservoirs to the transmission system Existing Site Improvements The Valley View Reservoir is a critical raw water storage component to the NID irrigation operation strategies for delivery of irrigation water to customers in the Little Ben and Kaliga Springs Roads area. This facility must remain operational during the initial construction phase or have a means to provide/maintain irrigation system service via a temporary system. The site has been designed to allow the relocated reservoir and associated piping to be constructed prior to abandoning the existing reservoir. The preliminary geotechnical report indicates that the area located under and around the solids drying beds is saturated due to seepage. The Valley View Canal is located on the hill above the proposed drying beds. Lining the existing canal above the WTP site may be necessary to prevent seepage in the area around the drying beds and should be investigated during detailed design to assess the seepage from the canal in the area above the proposed drying bed area. 3.3 LANDSCAPING A significant amount of landscaping will be provided on the north side of the facility to partially screen the view of the proposed chemical building from nearby neighbors. Landscaping will also be provided around the operations building and other areas of the treatment plant to provide visual enhancements for the site. Shade trees will be planted around the operations building for comfort and energy savings, and native plants will be used in other areas to the greatest extent possible. Raw and/or treated water may be utilized to provide water for the irrigation system. NVID Regional Water Supply Project

54 Basis of Design The renderings show the WTP landscaping envisioned at maturity. The original plantings of trees and shrubs will likely include specimen type plantings, but not full grown trees and shrubs. 3.4 MAINTENANCE BUILDING A maintenance building is provided adjacent to the filter building, with direct access to the primary entrance road. 3.5 ENVIRONMENTAL The proposed predesign limits vegetation removal, to the greatest extend possible, to preserve as much of the natural character of the site as practical. As currently envisioned, the excavation of cut and fill during construction is projected to balance on the site, with minimal off hauling and remote disposal necessary. This grading balance improves energy efficiency during construction, saves landfill space and disposal fees, and reduces environmental impacts to neighbors along the haul route(s). 3.6 ARCHITECTURAL RENDERINGS Architectural renderings of the site are included in Figures 11 through 18. Multiple aerial and ground level perspectives are included to provide a visual aid to provide the basic look of the facilities. Final color schemes and architectural details will be determined during detailed design. Landscaping in the renderings is mature; initial plantings will be smaller and grow over time. Cost estimates reflect immature plantings. NVID Regional Water Supply Project

55 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 11 Southeast Aerial

56 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 12 Southwest Aerial

57 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 13 Northwest Aerial

58 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 14 North Perspective

59 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 15 Northeast Perspective

60 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 16 South Perspective

61 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 17 Southwest Perspective

62 X:\Active Projects\Nevada Irrigation District - NVID\NVID Regional Water Supply\Technical Memorandum\WTP Predesign\FINAL - June 2010\BJG Updated Renderings \Figures_ARCH.indd MLM Source: BJG Architecture and Engineering, 2010 Figure 18 Northwest Perspective

63 Basis of Design 4.0 STRUCTURAL/ARCHITECTURAL DESIGN CRITERIA Structural and architecture considerations are discussed in this section. 4.1 STRUCTURAL DESIGN CRITERIA This section describes and establishes the basis of structural design requirements for all of the WTP structures. Based on preliminary site planning, the major structures located within the plant consist of an administration and operations building, chemical building, rapid mix/flocculation/sedimentation basins, the filters and filter building, maintenance shop, and blower room, UV and backwash pump station building, and the treated water storage tanks. All buildings are classified as Occupancy Category IV per CBC table and as such shall be designed as essential facilities. The site is located at approximately latitude and longitude at an elevation of less than 1,600 feet Design Codes and References Design of structural components and equipment anchorages will comply with the design codes, standards and project reports listed below Design Codes California Building Code (CBC), 2007 Edition ACI Building Code Requirements for Structural Concrete ACI 350R-01 Environmental Engineering Concrete Structures ACI /ASCE 5/TMS 402 Building Code requirements for Masonry Structures AISC Manual of Steel Construction, 13 th Edition Standards ASCE 7-05; Minimum Design Loads for Buildings and Structures ACI 302.1R-89 Guide for Concrete Floor and Slab Construction ACI Seismic Design of Liquid-Containing Concrete Structures ACI ; Tightness Testing of Environmental Engineering Concrete Structures API 650, Appendix E; Seismic Design of Storage Tanks 350.4R-04; Design Considerations for Environmental Engineering Concrete Structures Project Reports Geotechnical Report and Supplements Detailed geotechnical investigation will be required during final design for foundation and structural design Concrete Design Concrete design will be based on ACI 318 with load combinations as defined in the CBC. Design of water-containing structures, including the floor, wall, columns and roof will be based on ACI 350, with a maximum Z value of 115 kips/inch. NVID Regional Water Supply Project

64 Basis of Design Structural and Miscellaneous Steel Structural and miscellaneous steel members will be designed in accordance with the AISC Manual of Steel Construction. Metal decking will be ICBO approved. Cold-formed steel structural members will be designed in accordance with recommendations in the CBC Masonry Design Design of masonry structures shall be in compliance with the CBC and ACI Timber Design Design of timber structures will follow the requirement of the CBC. Plywood will be American Plywood Association rated Structural I, Exposure One. Lumber in contact with earth or exposed to weather will be preservative-treated or kiln dried wood Materials and Design Stresses Table 18 outlines the minimum strength, allowable stresses and/or grades to be used on this Project. Materials Table 18 Materials and Design Stresses Design Stresses Concrete Compressive strength f c = 4,000psi at 28 days Reinforcing steel ASTM A615, fy = 60,000psi Structural Steel and Fasteners Rolled shapes (except wide-flanges) and plates ASTM A36, fy = 36ksi Metal Deck ASTM 653 SQ, G60, fy=38ksi Bolts ASTM A325N Stainless steel anchor bolts ASTM A307 (All anchors and fittings exposed to water will be stainless steel) Masonry Masonry unit assembly ASTM C90, f m = 1500psi Compressive strength of CMU units 1,900 psi Compressive strength of mortar ASTM C270, f c = 1800 psi Compressive strength of grout ASTM C476, f c = 2000 psi Timber and Wood Douglas fir larch, No. 1 or better Structural Aluminum Plate and bars ASTM B211 Aluminum hatches Alloy 6061-T6 Tubing ASTM B429 Geotechnical (e.g. allowable bearing pressures) Per geotechnical report NVID Regional Water Supply Project

65 Basis of Design Structural Stabilities The overturning moment of major structural frames due to wind or seismic loads will not exceed two-thirds of the dead load resisting moment, unless the structure is anchored to resist the excessive moment. The total resisting force to foundation sliding will be provided by frictional forces from dead load and passive soil resistance in accordance with the Project geotechnical report. A factor of safety of 1.5 for sliding and a factor of 2.0 for overturning to resist wind or seismic loads will be used in the design. A safety factor of 1.5 will be provided against sliding and 2.0 against overturning for isolated retaining wall structures or in-ground structures with unbalanced backfill loads during operation. All equipment will be anchored using cast-in-place anchor bolts. Epoxy adhesive bolts may be used with the approval of the Project Engineer. Use of expansion anchors for anchoring vibratory equipment is not permitted Loading Criteria Dead, live, wind and seismic loads will be in accordance with the CBC and as specified below. Soils pressures will be in accordance with the geotechnical report Dead and Live Loads Table 19 outlines the dead and live loads to be used on this Project. Dead Loads Criteria Weight of structure and equipment Live Loads Roof Table 19 Dead and Live Loads Use Actual Code Snow and drift loads as determined below Office floor Per IBC Table Chemical storage areas 250 psf Suspended floor slab Per IBC Table Slab on grade Traffic areas CBC Table Lateral Loads At-rest pressure Lateral dynamic soil load Lateral hydrostatic pressure 100 psf in office areas, 250 psf in non office areas Per geotechnical report Per geotechnical report 63 pcf Lateral hydrodynamic pressure Per referenced documents in ASCE 7 Chapter 23 Weight of soil Per geotechnical report NVID Regional Water Supply Project

66 Basis of Design Seismic Loads Ss = (Site Class B), S1 = (Site Class B) SMs = 0.604, SM1 = Site Class D Fa = 1.472, Fv = SDs = 0.403, SD1 = I = 1.5, Ip = Wind Loads 3 second gusts = 85 mph (Placer County Code Section P) Wind Exposure = C I = Snow Loads Pg = 20psf (Placer County Code Section P) Drift and eave loading as required Vibration Loads Adverse effect of vibration from the operation of the vibratory machinery shall be considered in the design of all support structures. If applicable, floor vibration due to footfall will be evaluated Special Inspection Special inspection will be provided in accordance with CBC Section Masonry, if applicable, shall use Level 2 inspections outlined in CBC Table The special inspector will observe the work for conformance with the design drawings and specifications and will furnish inspection reports for NID and any building officials with jurisdiction. 4.2 ARCHITECTURAL CRITERIA This section describes and establishes the basis of architectural design requirements for all of the structures in the NID Regional Water Supply Project Water Treatment Plant. Based on preliminary site planning, the major structures located within the plant consist of an administration and operations building, a chemical building, a rapid mix/flocculation/sedimentation basin building, a filter gallery building, a UV and backwash pump building, a maintenance shop and a blower room Building Codes The buildings designed for the Project will conform to the latest State and/or County adopted edition of the California Building Code and California Title 24 Energy Code. Each building will be categorized by its functional occupancy and a basic code study will be given for each. The buildings will be designed with adequate space for both the first 10 MGD phase and the final 40 MGD phase. NVID Regional Water Supply Project

67 Basis of Design Code Analysis The code analysis for the various buildings located at the WTP are presented in Tables 20 through 26. Table 20 Administration/Operations Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code B +/- 5,000 s.f. IIB or IIIB 19,000 23,000 s.f. 4 Stories Possible 1 hr. separation for mechanical and storage. 20 ft. at North >30 ft. at South, East and West IIB - 0, IIIB 1 hr. IIB not required, IIIB 3/4 hr. protection Accessible Not Required Table 21 Chemical Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code S1 +/- 14,600 s.f. IIB or IIIB 17,500 s.f. 3 stories Possible 1 hr. separation for storage and electrical room. 20 ft. at South > 30 ft. at North, East & West IIB - 0, IIIB 1 hr. IIB not required, IIIB ¾ hr. protection Non-Accessible Required or 1 hr. fire wall separation NVID Regional Water Supply Project

68 Basis of Design Table 22 Rapid Mix/Flocculation/Sedimentation Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code F2 +/- 13,500 sf. IIB or IIIB 18,000-23,000 s.f. 3 stories NA 20 ft. at South & West > 30 ft. at East & North IIB 0, IIIB 1 hr. NA Non-Accessible Not required Table 23 Filtration Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code F2 +/- 14,500 s.f. IIB or IIIB 18,000-23,000 s.f. 3 stories NA 0 ft. at East & West end walls 10 ft. at North wall IIB 0, IIIB 1 hr. 1 hr. North Wall 2 hr. East party wall 3 hr. West party wall Not allowed at party walls ¾ hr. at 1 hr. exterior wall Non-Accessible Not required NVID Regional Water Supply Project

69 Basis of Design Table 24 Maintenance Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code S1 +/- 4,000 s.f. IIB or IIIB 17,500 s.f. 3 stories 3 hr. separation at East party wall 0 ft. at East party wall 20 ft. at North >30 ft. at South and West IIB - 0, IIIB 1 hr. Not allowed at party walls ¾ hr. at 1 hr. exterior wall Non-Accessible Not Required Table 25 Blower Room Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code F2 +/- 900 s.f. IIB or IIIB 18,000-23,000 s.f. 3 stories 2 hr. separation at West party wall 0 ft. at west party wall >30 ft. at North, East and South IIB - 0, IIIB 1 hr. Not allowed at party walls ¾ hr. at 1 hr. exterior wall Non-Accessible Not required NVID Regional Water Supply Project

70 Basis of Design Table 26 UV Disinfection and Backwash Pump Building Criteria Occupancy Floor Area Type of Construction Basic Allowable Area Allowable Height Special Requirements Minimum Distance to Property Line Fire Resistances of Exterior Walls Opening Protection Handicap Access Sprinkler System Code F2 +/- 1,600 s.f. IIB or IIIB 18,000-23,000 s.f. 3 stories NA > 60 ft. IIB - 0, IIIB 0 hr. NA Non-Accessible Not required Buildings The floor elevation of all buildings will be set above the overflow elevation of all systems or suitable protection from overflows will be provided. Architectural renderings and floor plans are provided for the major structures in this section. The basic theme is presented, although the final color selections will be made at a later date Administration/Operations Building The administration/operations building will be located near the center of the site and will set the architectural tone for the rest of the plant structures. The building will serve as the visitor center and location of the offices for the plant operating staff. The program for the building includes; a control room, offices, lobby, water laboratory, meeting room, breakroom, lockers, sleeping quarters, restrooms, storage and mechanical room. The layout of the building will be in an east west direction to take advantage of a passive solar design to maximize energy efficiency. Views will be to the south for supervision of the main access road and water storage tanks. Views to the north will be for supervision of the chemical building. The materials for the exterior walls will be selected for durability and ease of maintenance. The windows will be aluminum frame with a one-inch insulated glazing system. Glazing will be designed to maximize efficiency with daylighting and minimizing solar heat gain. The roof will be a low maintenance material. The interior of the building will be gypsum board walls with a paint finish. A ceramic or porcelain tile floor finish will be selected for the lobby and restrooms. The laboratory, breakroom and lockers will have a vinyl composition tile type finish or epoxy type flooring depending on durability requirements. The offices, meeting room, storage and sleeping quarters will have a carpet finish. An access flooring panel system will be used for the control room and plant equipment control office. The mechanical room will have a sealed concrete finish. The building will be fully insulated to comply with the current California Title 24 Energy Code. NVID Regional Water Supply Project

71 Basis of Design The administration/operations building will be not be constructed as part of the initial 10 MGD phase of the Project. A temporary operations and control room will be constructed as part of the Phase 1 chemical building. Provisions will be made in the Phase 1 design to allow for efficient relocation of the temporary controls to the permanent administration/operations building during future phases of the Project. As part of this BDTM, two conceptual floor plans, including architectural renderings, were developed. Figures 19 through 27 depict to potential administration/operations building layouts. Option 1 is the preferred layout. NVID Regional Water Supply Project

72 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 19 OPTION 1 FLOOR PLAN

73 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 20 OPTION 1 N.E. AXONOMETRIC VIEW

74 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 21 OPTION 1 ENTRY PERSPECTIVE

75 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 22 OPTION 2 1ST FLOOR PLAN

76 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 23 OPTION 2 2ND FLOOR PLAN

77 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 24 OPTION 2 S.E. AXONOMETRIC VIEW

78 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: ARCHITECTURE + ENGINEERING BJG FIGURE 25 OPTION 2 N.E. AXONOMETRIC VIEW

79 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 26 OPTION 2 ENTRY PERSPECTIVE

80 3875 ATHERTON ROAD ROCKLIN, CA PH: FX: BJG ARCHITECTURE + ENGINEERING FIGURE 27 OPTION 2 ENTRY PERSPECTIVE

81 Basis of Design Chemical Building The chemical building will be located to the north of the administration building. The building will serve as the storage area for the chemicals used in the treatment process. The building will be broken down into six major storage areas, with an area for chemical feed equipment, an electrical room, and a circulation bay. The materials for the exterior walls will be constructed of concrete masonry or similar material selected for durability and ease of maintenance. The roof will be a low maintenance material. The roof will be divided up into multiple sections to break up the scale of the building due to the overall length. Delivery of the chemicals will be monitored from the administration building for safety. The chemical building for the initial 10 MGD phase of the Project is shown previously in Figure 9. Plant controls will be temporarily housed in the electrical room in the first phase. Subsequent phases of the Project will include relocating the plant controls to a new control building and the addition of further sodium hypochlorite and aluminum sulfate chemical bays. The 10 MGD aluminum sulfate bay will become a storage room and the sodium hypochlorite will become additional polymer storage when plant built out is complete. The soda ash chemical room will be built in its entirety during the first phase for ease of construction and phasing Rapid Mix/Flocculation/Sedimentation Structures The rapid mix, flocculation, and sedimentation structures will be located to the east of the chemical and administration buildings. The exterior walls of the basins will be constructed of reinforced cast-in-place concrete. The structures will be built according to the determined phasing of the Project. The first 10 MGD treatment train will be built during the first phase. Each additional train can be added during the following phases of the plant. The phasing of these structures is depicted in Figure 6 in Section Filter Building and Filters The filter gallery building will be located south of the rapid mix/flocculation/sedimentation basins. The exterior walls of the structure will be constructed of reinforced concrete masonry or similar durable material. The interior walls for the filters will be constructed of reinforced castin-place concrete. The control panel area will be roofed to match the materials chosen for the remainder of the Project. Three filters will be constructed during the first 10 MGD phase. The filters will be covered with a canopy shade structure for the initial phase. A building will be constructed over the filters during subsequent phases of the Project. All piping to accommodate the additional filter bays for the plant build out will be installed in the initial construction phase. NVID Regional Water Supply Project

82 Basis of Design Maintenance Shop The maintenance shop will be located to the west side of the filter gallery. The exterior walls will be constructed of materials to compliment and match the materials, colors and textures of the entire Project. The roof materials to be selected will match the materials of the adjacent filter gallery. The shop will be constructed during the second phase of construction for cost efficiency purposes Blower Room Building The blower room building is located to the east end of the filter gallery. The exterior walls of the structures will be constructed of reinforced concrete masonry or similar durable material. The roof materials to be selected will match the materials of the adjacent filter gallery. The entire blower room building will be constructed during the initial phase of construction UV Disinfection Building The UV disinfection building is located adjacent to the treated water storage reservoirs. The exterior walls of the structures will be constructed of reinforced concrete masonry or similar durable material. The roof materials to be selected will match the materials of the remainder of the Project. The entire UV disinfection building will be constructed during the initial phase of construction; however the building will only be equipped for the 10 MGD phase Backwash pump station The backwash pump station building will share a common wall with the UV disinfection building. The exterior walls of the structures will be constructed of reinforced concrete masonry or similar durable material. The roof materials to be selected will match the materials of the remainder of the Project. The backwash pump station building will be constructed during the initial phase of construction; however the building will only be equipped initially for the 10 MGD phase Pressure Reducing Structure/Future Hydroelectric Plant The pressure reducing structure will be located prior to the flocc./sed. basins. The exterior walls of the structures will be constructed of reinforced concrete masonry or similar durable material. The roof materials to be selected will match the materials of the remainder of the Project. This structure will be constructed in phases, with the pressure reducing components installed during the initial phases, followed by the addition of hydroelectric generation equipment at some point in the future. NVID Regional Water Supply Project

83 Basis of Design 5.0 ELECTRICAL DESIGN CRITERIA The electrical design criteria include all the electrical equipment for the various treatment processes and the general electric requirements for the site. 5.1 POWER SYSTEM SUPPLY Power to the site will be provided from PG&E overhead power supply, coming from the south off of Big Ben Road and then following the WTP access road to the transformer located adjacent to the finished water storage tank, pump station, and UV disinfection facility. From this transformer, all power distributed on the WTP site for the treatment facilities will be buried underground. The WTP will require a new electrical service that is large enough to meet all of plant s power requirements. The following sections will discuss some general power requirements, voltage requirements, and back-up power General Power Requirements The power feed to the WTP is estimated to be 12 kv. The power feed will connect into a transformer that will have the capacity to power the entire treatment plant site. The transformer will step down the power to three phase, 480 volts, which will then be delivered across the WTP site. The process equipment such as the electric motors for the mixers, electric pumps, air blowers, UV lamps will be powered by 480 volt motor control centers (MCCs). Other typical equipment for miscellaneous building loads, lighting, and HVAC will be powered separately through transformers and 480 volt panel boards. Table 27 lists estimated electrical loads for the different WTP components. These electrical loads will be adjusted and confirmed in the next design phase of the Project. Table 27 Preliminary WTP Electrical Loads Component Pre-Treatment Processes Filtration and UV Facility Pump Stations Load (kva) 250 kva 650 kva 850 kva NVID Regional Water Supply Project

84 Basis of Design Voltage Requirements General voltage requirements for components of the treatment plant are shown in Table 28. Table 28 WTP Electrical Loads Component General Service On-site Distribution MCC Motors > 0.5 hp Motors < 0.5 hp Other (Lighting, etc.) Voltage (Phase, Volts) Three-phase, 12,470 V Three-phase, 480 V Three-phase, 480 V Three-phase, 480 V Single-phase, 120 V Single-phase, 120 V Back-up Power Back-up power for the WTP will be supplied by a diesel powered generator that will provide power to the essential system components in the event of a power outage. The generator must be CARB certified and be approved for installation by the Sacramento Air Quality Board. The generator at minimum will supply the power to keep one 10 MGD treatment train fully operational for the initial phases of the Project (up to 20 MGD plant capacity). For the WTP buildout capacity of 40 MGD, a larger single generator will be needed to power the essential systems for the entire treatment process. Essential System components to be powered by the backup generator will include: Traveling screen Rapid mixer Flocculation and sedimentation basins Filtration system, including backwash supply and recycled water pumps Chemical feed and disinfection systems (UV and chlorine) SCADA system Fire suppression and life safety systems. Office and lab building Emergency lighting The size of generator is estimated to be 1,250 kw. The WTP will have the ability to automatically switch between the main power feed and the back-up power supply in the event of a power outage. The generator size will be confirmed during final design of the WTP. NVID Regional Water Supply Project

85 Basis of Design 5.2 ELECTRICAL POWER EQUIPMENT The electrical equipment for the WTP will be required to be designed according to the codes and references in the Section 5.3. The electrical equipment for the WTP will meet the general guidelines below: Fire and life safety systems will be installed where required by national and local codes. It is anticipated that only the chemical building and administration/operations building will require fire and life safety systems. The large quantity of stored chemicals will require a fire and life safety system in the chemical building, and the continuous personnel occupation of the administration/operations building will also require a fire and life safety system. Power transformers will be provided where necessary and be designed to industry standards. Outdoor transformers will be weatherproof and fully enclosed. Lighting for the buildings and for the general WTP site will conform to the requirements set by the Illumination Engineering Society handbook and the State of California Title 24 requirements. A security system will be provided for the entire WTP. The security system will likely include cameras, door and hatch alarms, security fences, and key card entry pads. A plant wide telephone system will be provided. The system will connect to all the buildings located at the WTP through underground conduit. All electric equipment including process devices, transformers, MCCs, switch gear, and panel boards will be properly grounded according to the NEC. Lightning protection will be provided where necessary for all buildings and structures. Raceways will be selected based on their specific location, exposure to moisture, corrosion, temperature, and voltage rating. Duct banks will be separated when power wiring is below 600 volts and also from the instrumentation and communication wiring. Motors for the mixers, the screening equipment, the pumps, and other various mechanical operations will be designed for high efficiency ratings. Variable frequency drives (VFD) will be required for such processes as the rapid mixing motors and will be rated and designed for each individual application. Motors will be powered from the MCCs. Motors that are larger than 100 horsepower typically will require a solid-state reduced voltage starter. In place of MCCs 480 volt power centers may be provided for locations with only a few to no motors. A three phase 480 volt power center will be designed and rated to provide the power for UV system. NVID Regional Water Supply Project

86 Basis of Design 5.3 DESIGN CODES AND REFERENCES The electrical design will comply with the latest editions of the design codes and references. The current codes are listed below Design Codes National Electrical Code (NEC), 2008 edition. National Electrical Safety Code (NESC), 2007 edition Design References Diesel-Gas generator shall meet the current emissions requirements as mandated by the Sacramento Metropolitan Air Quality Management District for Standby applications. CARB (California Air Resources Board) Certified. IEEE446 (Institute of Electrical and Electronics Engineers ) Recommended Practice for Emergency and Standby Power Systems for Commercial and Industrial Applications NFPA70 (National Fire Protection Agency) - Equipment shall be suitable for use in systems in compliance to Article 700, 701, and 702. NFPA110 (National Fire Protection Agency) Emergency and Standby Power Systems. The generator set shall meet all requirements for Level 1 systems. Level 1prototype tests required by this standard shall have been performed on a complete and functional unit, component level type tests will not substitute for this requirement. ISO (International Organization for Standardization) BS5514 (British Standard) SAE J1349 (Society of Automotive Engineers) ISO3046 (International Organization for Standardization) DIN6271 (Deutsches Institut für Normung) NEMA MG part 32 (National Electrical Manufacturers Association). Alternator shall comply with the requirements of this standard. UL2200. (Underwriters Laboratories ) The generator set shall be listed to UL2200 or submit to an independent third party certification process to verify compliance as installed. International Fire Code. NFPA 30 (National Fire Protection Agency) - Flammable and Combustible Liquids Code. NFPA 37 (National Fire Protection Agency) -Standard for Installation and Use of Stationary Combustion Engines and Gas Turbines. NVID Regional Water Supply Project

87 Basis of Design The generator set and supplied accessories shall meet the requirements of all applicable state and local codes. Occupation Safety and Health Act (OSHA) standards. Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems, International Electrical Testing Association (NETA), 2009 edition. Instrument Society of America (ISA) Occupational Safety and Health Administration (OSHA) Institute of Electrical and Electronics Engineers (IEEE) Illuminating Engineers Society (IES) National Electrical Manufacturers Association (NEMA) All electrical design will also conform to the requirements as set forth in the local codes. 6.0 INSTRUMENTATION AND SCADA The instrumentation and Supervisory Control and Data Acquisition (SCADA) system will be designed per industry and NID standards and to match other equipment in NID's existing system. The instrumentation and control system will include a plant wide SCADA system using Programmable Logic Controllers (PLC), control panels, motor control centers (MCC), field equipment, personal computer workstations, portable laptop workstations, and communication instrumentation. 6.1 SCADA SYSTEM OVERVIEW The treatment plant will be monitored and controlled through an automated SCADA system. The SCADA system will allow the water treatment processes and equipment to be effectively monitored and allow for automatic or manual operation of the plant. The plant wide SCADA system will interface with the monitoring equipment, transmitters, PLCs, computers, and associated software. The SCADA system will provide key indication and alarms (at a minimum) to the NID and City of Lincoln s SCADA systems. 6.2 SYSTEM RELIABILITY Continuous operation of a WTP is dependant on the overall SCADA system. Below is a list of measures that will be used to ensure system reliability. Multiple workstations for operators and back-up databases. The PLCs will control and monitor the plant, while personal computers will be supplied as the Human Machine Interfaces (HMIs). Therefore in the event of a personal computer failure, the WTP s performance will not be affected. NVID Regional Water Supply Project

88 Basis of Design Uninterruptible power supplies (UPS) will be provided for PLCs and personal computers. The system will have the capability for expansions of the PLC and input/output (I/O). This will ensure capacity through all the future plant phases up to 40 MGD for the SCADA system. When equipment fails or communications links fail, an alarm will be activated. Major process equipment will be equipped with hand controls at the MCC or in the field as desired. The WTP can be operated locally with a PLC or in automatic mode or manual mode with a PLC. If communication is lost for a certain period of time to a PLC, the PLC will go into a fail safe mode. 6.3 INSTRUMENTATION Instrumentation will be used to monitor and control all the WTP processes. The instrumentation will also include alarms for treatment problems, system malfunctions, and safety violations. Instrumentation will include the following components: Monitoring treated water tank levels Monitoring water levels in the gravity thickening clarifiers Monitoring chemical storage levels Magnetic flow meter instrumentation Monitoring flows and levels for pump controls Streaming current monitor instrumentation Raw water turbidity, ph, temperature, and conductivity monitoring equipment Treated water turbidity, ph, temperature, and particle count monitoring equipment Flow control equipment Pipeline Pressure Hydroelectric Generation status and performance parameters City Metering Station parameters including flow, pressures, tank levels and pump status City of Lincoln treated water system parameters including tank levels, system flows, and pressures NVID Regional Water Supply Project

89 Basis of Design 6.4 MODES OF OPERATION The equipment at the WTP will have the ability to be operated in three different modes. Those modes include hand, automatic, and SCADA manual and are defined as follows: The hand mode allows a piece of equipment to be operated locally and manually from the MCC. The automatic mode allows equipment to be operated automatically by the PLC or work station. A PLC will automatically make adjustments to the equipment to operate per the operator s set points. The SCADA Manual mode allows equipment to be operated from an operator workstation such as an operator laptop or SCADA workstation. An example of this is shown in Figure MONITORING AND CONTROL INSTRUMENTATION The instrumentation for the various major water treatment processes is discussed below. All monitored data will be stored and available for historical analysis Raw Water and Rapid Mixing System Raw water will enter the plant through the pressure reducing and/or the hydroelectric generation facilities that will reduce the pressure. A raw water sample pump will deliver water continuously to the laboratory and to a water quality monitoring station which will monitor the turbidity, temperature, ph, and conductivity. This equipment will provide the necessary raw water quality data for determining the proper chemical dosages. The primary coagulant and ph adjustment chemicals will be fed into the rapid mixing basins. These chemical pumps will be flow controlled and will have the ability to be adjusted based on downstream water quality data. The vertical rapid mixers will be equipped with variable speed drives and will be controlled by a PLC. The operator will have the ability to adjust the speed of the rapid mixers to match the plant influent flows and desired velocity gradients. After chemical injection at the rapid mixing basin, a sample pump will deliver water to the laboratory, to a water quality monitoring station, and to a streaming current monitor (SCM). This equipment will provide the water quality data necessary for any adjustments to chemical dosages. NVID Regional Water Supply Project

90 Basis of Design Flocculation, Sedimentation, and Filtration System The motors for the vertical paddle wheel flocculators will be controlled by a PLC. Chemicals for ph adjustment and filter aid will be fed into the water line after the sedimentation basin. These chemical feeds will be dosed by the water quality monitoring equipment and flow paced under PLC control. A packaged control system for each filter unit will be provided and will connect back into the WTP SCADA system. Flow through each filter is controlled and monitored by a flow meter and flow control valve. Each filter will also be equipped with a turbidity meter and particle counter to monitor its performance. Compressed air systems will be required for pneumatically-operated valves, the air scouring system for the filters, for storing dry chemicals, and for any instrumentation that requires compressed air Gravity Thickening Clarifiers and Recycle Pump Station The gravity thickening clarifiers will receive flows from the sedimentation basins, filter backwash cycles, filter to waste cycles, sampling equipment, and decanted water from the drying beds. The water levels in the gravity thickening clarifiers will be monitored by level transducers. The water levels will be maintained by the recycle pumps. Two gravity thickening clarifiers will act as solids removal basins, while the third clarifier will act as an equalization basin allowing for a constant return rate of flow back to the head of the plant. The recycle pumps will be installed with variable speed drives controlled by a PLC. The recycled water will be monitored by a turbidity meter and a flow meter. Pumps that will transfer collected solids from the gravity thickening clarifiers to the drying beds will be controlled through a PLC Treated Water Storage Tanks and Distribution A flow meter and turbidity meter will be installed on the combined filter effluent pipeline to measure the filtered water quality and flow. Chemicals for ph adjustment and disinfection will then be fed into this pipeline. These feeds will be flow paced and PLC controlled. As the water enters the storage tanks a sample pump will deliver water to the laboratory and to a water quality monitoring station to measure the turbidity, temperature, ph, and chlorine residual. These measurements help to determine and adjust chemical dosages. The water levels in the finished storage water tanks will be monitored by level transducers. The levels in the tanks will be controlled by adjusting the flow rate through the filters. The finished water leaving the storage tanks will be sent to the laboratory by a sample pump that will also feed water quality monitoring equipment which will monitor turbidity, ph, and chlorine residual. These measurements will help to make any adjustments to the chemical dosages. NVID Regional Water Supply Project

91 Basis of Design Chemical Feed Systems Metering pumps will feed the chemicals for coagulation, coagulation aid, ph adjustment, filter aid, solids thickening, and disinfection. The levels for the chemical storage tanks will be monitored by high and low level switches. Each chemical system will be equipped with a PLC that will be controlled from the plant wide SCADA system UV Disinfection System The UV disinfection system will be connected to the WTP SCADA system to monitor performance and equipment malfunctions. 6.6 PROVISIONS FOR REMOTE MONITORING AND AUTOMATIC OPERATION As mentioned previously, all the major plant process equipment will have the ability to be operated remotely and automatically. Each of these major systems will be equipped with a PLC that will normally operate automatically based on algorithms that utilize set design points for flow, dosage, water quality, and water levels. An operator will have the ability to make changes or adjustments to the controls via set points. Additionally the operator may take manual control of most PLC controlled equipment and manually override the PLC. A secured virtual private network (VPN) will give an operator the ability to securely log into the SCADA system to monitor and control the system via the internet or a dial up connection. In the event that a piece of equipment fails such as a pump, the system will be programmed to automatically start identical stand-by equipment. In the event the PLC fails, the equipment connected to the PLC will be engineered to go into a fail safe mode. The PLC will also be programmed to retain the previous settings in the event of a power failure. In the event of a power outage, the WTP will be configured for continuous operation. 6.7 SCADA SYSTEM SECURITY The SCADA system will incorporate three separate levels of security. The first security level will include operators which will allow an operator to view and operate the control system. The next security level will include supervisors, which will allow a supervisor to access and change set points in the control system. A potential third level of security, if desired by NID, would include managers and engineers, which would allow the manager or engineer to access and change the P & ID set points. All set points will be visible for all three security levels, however only managers or engineers will have ability to change them. 6.8 COMMUNICATIONS AND SOFTWARE Two SCADA PCs will be located in the administration/operation building. The SCADA machines will continuously collect process monitoring data from the PLCs. The process monitoring data will also be available at the field instrument level in the event of a PLC failure. The field equipment will also have the ability to be controlled manually in the event of a PLC failure. NVID Regional Water Supply Project

92 Basis of Design The onsite system communication at the WTP will be Ethernet including a combination of CAT5e and fiber optic cabling. For offsite communication, a fiber optic cable or radio telemetry will link the WTP SCADA system to NID s other facilities. The use of fiber optic, telephone (i.e. DSL, T1, Leased Line or other means) or radio will be explored fully during the design process. If the radio telemetry option is used, the remote telemetry unit (RTU) and associated antenna/mast will be constructed at the WTP and City of Lincoln metering station and will communicate with the NID SCADA control and City of Lincoln SCADA control. A radio path survey should be conducted to verify the viability of the communications path. The SCADA system will also be connected to operator work stations that will all be running similar SCADA software and have common access to the databases. All the operator work stations will have the same ability to monitor and control the system. The control of the system may be restricted as required, or desired, by NID using the security schemes discussed in Section 6.7 SCADA System Security. The operator work stations will the have following abilities to monitor and control the system. Real time and historical trending data presented in a graphical form. Real time indications, parameters, alarms and setpoints that are presented in a clear and concise graphical interface. The PLC will interface with the database to present live data monitoring. The ability to graphically display the treatment processes and data of the equipment in the field via the PLCs and SCADA software. Alarm notification and the ability to record alarms and events and display alarms for each piece of equipment. The alarm system will have a software based Autodialer program that will call the selected operators in the order set by the operations staff. The system can be reconfigured by the operations staff as on-call personnel are changed. 7.0 OPINION OF PROBABLE COST Facility costs are included in this section. 7.1 GENERAL DISCUSSION This section presents the opinion of probable construction costs for the 40 MGD treatment facility, cost assumptions, notable cost impacts, the probable construction costs for a 10 MGD initial facility phase, and estimated operations and maintenance costs. It also presents a brief discussion for alternative treated water storage phasing that could be considered if initial capital funds are limited. All costs are planning level, based on the 10 percent facility design. Treatment facility and finished water storage facility costs are separated to demonstrate the cost of treatment versus storage. A 25 percent contingency is included at this planning level estimate and can be reduced after more detailed design allows quantity and unit price estimates are refined. NVID Regional Water Supply Project

93 Basis of Design 7.2 OPINION OF PROBABLE CAPITAL COSTS Buildout 40 MGD Facility Capital Costs The opinion of probable costs for the 40 MGD treatment facility is $79,408,000 including electrical/instrumentation, engineering, legal, administration, construction management, and a 25 percent contingency. Adding the $41,130,000 for 39 million gallons of treated water storage and land acquisition costs of $3,832,000, brings the combined facility cost to $124,370,000. The Mobilization/Demobilization estimate is approximately 5% of the Treatment Facility subtotal plus the Finished Water Storage subtotal, taken before engineering, legal, administration, and CM and contingency. A summary of the individual component costs is presented in Table 29. Table MGD (Buildout) NID WTP Opinion of Probable Capital Costs (a) NID WTP Site Plan Reference 1 Treatment Facility Project Component Opinion of Probable Cost 1.1 Mobilization/Demobilization $4,250, Sitework $3,540, Process Components Site Piping $4,400,000 2 Chemical Building & Systems $3,180,000 3 Administration & Operations Facility $1,140,000 7 Maintenance Building $680, Screening & Washing Facility $860,000 4 Rapid Mix Facility $560,000 4 Flocculation Basin $2,420,000 4 Sedimentation Basin $3,490,000 6 Filtration Facility $7,770, UV Disinfection $5,420,000 8 Gravity Thickener Clarifiers $1,800, Solids Dewatering/Drying Bed Equipment $1,460, Backwash Supply Pump Station $590, Recycle Water Pump Station $380, Solids Pump Station $260,000 9 Decant Pump Station $150,000 Subtotal $42,350,000 Electrical/Instrumentation (25%) $10,588,000 Subtotal $52,938,000 Engineering, legal, administration, and CM (20%) $10,588,000 Subtotal $63,526,000 Contingency (25%) $15,882,000 Treatment Facility Subtotal $79,408,000 NVID Regional Water Supply Project

94 Basis of Design NID WTP Site Plan Reference 2 Finished Water Storage Project Component Opinion of Probable Cost Finished Water Storage Tanks $21,250, Tank Site Work $4,500, Tank Site Piping $1,670,000 Subtotal $27,420,000 Engineering, legal, administration, and CM (20%) $5,484,000 3 Land Acquisition (b) Subtotal $32,904,000 Contingency (25%) $8,226,000 Finished Water Storage Subtotal $41,130, $35,000/acre $2,975,000 Subtotal $2,975,000 Land Acquisition Fee (3%) $90,000 Subtotal $3,065,000 Contingency (25%) $767,000 Land Acquisition Subtotal $3,832,000 FACILITY TOTAL $124,370,000 (a) ENR 20 Cities CCI = 8,800 (July 2010) (b) Land costs presented for planning purposes. Actual costs will be determined based on appraisals during negotiations. NVID Regional Water Supply Project

95 Basis of Design Cost Assumptions It was assumed that all excess excavated material will be used on site to avoid expensive hauling and disposal fees. Unit price assumptions used to arrive at the opinion of capital costs are presented in Table 30. Site Work: Table 30 WTP Unit Price Assumptions Item Units Price/Unit Clearing and Grubbing acre $1,500 Excavate, Load and Haul Soil cubic yard $7 Excavate, Load and Haul Rock cubic yard $15 Place and Compact Native Material cubic yard $3 Place Native Rip-Rap cubic yard $5 Disposal hauling and landfill costs cubic yard $40 Aggregate Base Surfacing square foot $2 Asphalt Paving square foot $5 Concrete Curb & Gutter linear foot $20 Hydroseeding acre $4,000 Fencing linear foot $50 Landscaping acre $110,000 Site Piping: Process Piping $/in-diameter $10 Valves each varies Storm Drain Piping $/in-diameter $5 Process Junction Manholes each $5,000 Flow Meters (large diameter w/vault) each $120,000 Inlet/outlet Structures each $35,000 Storm Drain Manholes each $10,000 Storm Drain Inlets each $5,000 Sand/Oil Interceptors each $7,000 Septic Tank each $10,000 Leach Field each $20,000 Structures and Equipment: Building - slab on grade < 2,000 SF square foot $250 Building - with basement < 2,000 SF square foot $300 Building > 2,000 SF square foot $150 Filter building (excludes concrete) square foot $100 Canopy square foot $15 Individual structure excavation cubic yard $15 NVID Regional Water Supply Project

96 Basis of Design Item Units Price/Unit Structures and Equipment (cont ): Cast-in-Place Structural Concrete cubic yard $1,200 Mechanical Equipment each vendors $ Mechanical Piping lump sum varies Notable Cost Impacts Approximately 400,000 cubic yards of earth will be moved while developing the treatment facility and finished water storage sites, generating more than 200,000 cubic yards of excess material. The majority of excess material will be come from the tank site when the site is expanded from one tank to three tanks. The site work estimates include the cost to haul, place, and compact the excess material on-site. The geotechnical report indicates that a significant amount of rock will be encountered at the tank site. For estimating purposes it was assumed that all rock with seismic velocities greater than 7,000 feet-per-second will be blasted. The geotechnical report provides data from three seismic lines at or near the tank site, and based on the estimated depth to rock approximately 80,000 cubic yards of rock will need to be blasted. Additional site characterization may be warranted at future design phases to further refine costs associated with rock excavation. Land costs included for acquisition of the water treatment plant property have been included for budgeting purposes. Unit land cost estimates is based on recent selling prices of other properties in the area and is presented for budgeting purposed only. During land acquisition negotiations, anticipated sometime after the completion of CEQA, fair market value of land will be determined based on comparable sites in the area. NVID Regional Water Supply Project

97 Basis of Design Initial Facility 10 MGD Capital Costs The initial facility capital costs are based on a 10 MGD treatment capacity, with key components sized to allow prudent expansion to 40 MGD. For example, the 10 MGD site piping is sized for 20 MGD with utility corridors provided for future parallel piping. This approach allows for reasonable initial capital costs while still providing a plan to expand process piping in the future. Plant piping is sized for 40 MGD with the initial pumping capacities reduced, thus allowing expansion to 40 MGD by either changing or adding pumps in the future without replacing the entire pump station piping. Table 31 details the initial system capacities along with proposed adjustments to the 40 MGD facility to establish the scope of the 10 MGD initial facility phase. Project Component Table 31 Initial Facility Scope compared to 40 MGD Facility Initial Capacity Sitework - Site Piping 20 MGD Facility Expansions Required from 10 MGD to the 40 MGD Build Out Two additional water storage tank sites Additional paving for expansion Additional tank piping and some treatment component piping such as individual supply piping to future rapid mix structures. Additional 20 MGD capacity pipe to UV facility Chemical Building and Systems 10 MGD Increase building size from 9,000 SF to 14,000 SF Administration and Operations Building - Maintenance Building - Construct new building Construct new building (Initially combined with chemical facility for cost savings) Screening and Washing Facility 10 MGD Three additional screens Rapid Mix Facility 10 MGD Three additional structures Flocculation Basin 10 MGD Three additional basins Sedimentation Basin 10 MGD Three additional basins Filters 10 MGD Six additional filters enclosed in new building UV Disinfection 10 MGD Increase facility and capacity by 4 times Backwash Supply Pump Station 40 MGD No change Gravity Thickener Clarifiers 20 MGD Two additional clarifiers (60 diameter) Return Water Pump Station 20 MGD One additional pump Thickened Sludge Pump Station 20 MGD One additional pump Solids Dewatering/Drying Beds 20 MGD One additional drying bed with under drains Decant Pump Station 20 MGD Increased size of pumps Finished Water Storage 13 MG Two additional storage tanks (13 MG Each, 278 diameter) NVID Regional Water Supply Project

98 Basis of Design The opinion of probable costs for the 10 MGD treatment facility is $33,825,000, including electrical/instrumentation, engineering, legal, administration, construction management, and a 25 percent contingency. Adding the $14,280,000 for a 13 million gallon treated water storage tank and land acquisition costs of $3,832,000 brings the combined facility cost to $51,937,000. The Mobilization/Demobilization estimate is approximately 5% of the Treatment Facility subtotal plus the Finished Water Storage subtotal, taken before engineering, legal, administration, and CM and contingency. A summary of the 10 MGD facility capital costs are presented in Table 32. Some component costs are higher than typical 10 MGD facility components because they are sized to accommodate the future treatment capacity. NID WTP Site Plan Reference Table MGD WTP Opinion of Probable Capital Costs (a) 1 Treatment Facility Project Component Opinion of Probable Cost 1.1 Mobilization/Demobilization $1,650, Sitework $2,530, Process Components Site Piping $3,660,000 2 Chemical Building & Systems $2,090,000 3 Administration & Operations Facility $140,000 7 Maintenance Building $ - 19 Screening & Washing Facility $490,000 4 Rapid Mix Facility $140,000 4 Flocculation Basin $600,000 4 Sedimentation Basin $870,000 6 Filtration Facility $2,330, UV Disinfection $1,360,000 8 Gravity Thickener Clarifiers $600, Solids Dewatering/Drying Bed Equipment $360, Backwash Supply Pump Station $590, Recycle Water Pump Station $310, Solids Pump Station $210,000 9 Decant Pump Station $110,000 Subtotal $18,040,000 Electrical/Instrumentation (25%) $4,510,000 Subtotal $22,550,000 Engineering, legal, administration, and CM (20%) $4,510,000 Subtotal $27,060,000 Contingency (25%) $6,765,000 Treatment Facility Subtotal $33,825,000 NVID Regional Water Supply Project

99 Basis of Design NID WTP Site Plan Reference 2 Finished Water Storage Project Component Opinion of Probable Cost Finished Water Storage Tanks $7,200, Tank Site Work $1,600, Tank Site Piping $720,000 Subtotal $9,520,000 Engineering, legal, administration, and CM (20%) $1,904,000 3 Land Acquisition (b) Subtotal $11,424,000 Contingency (25%) $2,856,000 Finished Water Storage Subtotal $14,280, $35,000/acre $2,975,000 Subtotal $2,975,000 Land Acquisition Fee (3%) $90,000 Subtotal $3,065,000 Contingency (25%) $767,000 Land Acquisition Subtotal $3,832,000 FACILITY TOTAL $51,937,000 (a) ENR 20 Cities CCI = 8,800 (July 2010) (b) Land costs presented for planning purposes. Actual costs will be determined based on appraisals during negotiations. NVID Regional Water Supply Project

100 Basis of Design Table 33 compares the 10 MGD costs to the 40 MGD costs along with anticipated phasing costs. NID WTP Site Plan Reference Table 33 Probable Cost of Phasing from 10 MGD to 40 MGD (a) 1 Treatment Facility Project Component Probable 10 MGD Costs Probable Phasing Costs Probable 40 MGD Costs 1.1 Mobilization/Demobilization $1,650,000 $2,600,000 $4,250, Sitework $2,530,000 $1,020,000 $3,540, Process Components Site Piping $3,660,000 $740,000 $4,400,000 2 Chemical Building & Systems $2,090,000 $1,090,000 $3,180,000 3 Administration & Operations Facility $140,000 $1,000,000 $1,140,000 7 Maintenance Building $ - $680,000 $680, Screening & Washing Facility $490,000 $370,000 $860,000 4 Rapid Mix Facility $140,000 $420,000 $560,000 4 Flocculation Basin $600,000 $1,820,000 $2,420,000 4 Sedimentation Basin $870,000 $2,620,000 $3,490,000 6 Filtration Facility $2,330,000 $5,440,000 $7,770, UV Disinfection $1,360,000 $4,060,000 $5,420,000 8 Gravity Thickener Clarifiers $600,000 $1,200,000 $1,800, Solids Dewatering/Drying Bed Equipment $360,000 $1,100,000 $1,460, Backwash Supply Pump Station $590,000 $ - $590, Recycle Water Pump Station $310,000 $70,000 $380, Solids Pump Station $210,000 $50,000 $260,000 9 Decant Pump Station $110,000 $40,000 $150,000 Subtotal $18,040,000 $24,310,000 $42,350,000 Electrical/Instrumentation (25%) $4,510,000 $6,078,000 $10,588,000 Subtotal $22,550,000 $30,388,000 $52,938,000 Engineering, legal, administration, and CM (20%) $4,510,000 $6,078,000 $10,588,000 2 Finished Water Storage Subtotal $27,060,000 $36,466,000 $63,526,000 Contingency (25%) $6,765,000 $9,117,000 $15,882,000 Treatment Facility Subtotal $33,825,000 $45,583,000 $79,408, Finished Water Storage Tanks $7,200,000 $14,050,000 $21,250, Tank Site Work $1,600,000 $2,900,000 $4,500, Tank Site Piping $720,000 $950,000 $1,670,000 Subtotal $9,520,000 $17,900,000 $27,420,000 Engineering, legal, administration, and CM (20%) $1,904,000 $3,580,000 $5,484,000 Subtotal $11,424,000 $21,480,000 $32,904,000 Contingency (25%) $2,856,000 $5,370,000 $8,226,000 Finished Water Storage Subtotal $14,280,000 $26,850,000 $41,130,000 NVID Regional Water Supply Project

101 Basis of Design NID WTP Site Plan Reference 3 Land Acquisition (b) Project Component Probable 10 MGD Costs Probable Phasing Costs Probable 40 MGD Costs $35,000/acre $2,975,000 $ - $2,975,000 Subtotal $2,975,000 $ - $2,975,000 Land Acquisition Fee (3%) $90,000 $ - $90,000 Subtotal $3,065,000 $ - $3,065,000 Contingency (25%) $767,000 $ - $767,000 Land Acquisition Subtotal $3,832,000 $ - $3,832,000 FACILITY TOTAL $51,937,000 $72,433,000 $124,370,000 (a) ENR 20 Cities CCI = 8,800 (July 2010) (b) Land costs presented for planning purposes. Actual costs will be determined based on appraisals during negotiations Initial Facility Alternative Storage Phasing The treated water storage facility represents a significant component of the initial facility costs. Reducing the initial storage capacity could be considered as an alternative approach to manage the initial construction costs. It is estimated that a 4 million gallon welded steel storage tank could be built on site for approximately $4 million, reducing the initial facility costs by approximately $9.5 million. The optimum finished water storage volume required to meet all regulatory requirements and system demands will need further investigation and discussions with NID, City of Lincoln, and regulators. The investigation will include an existing system storage volume inventory available to meet the MDD requirement, which could affect the required amount of treated water storage at the site. 7.3 OPINION OF PROBABLE OPERATIONS AND MAINTENANCE COSTS The estimate of probable operations and maintenances costs are $500,000 annually for 10 MGD facility, and $1.9 million annually for the 40 MGD facility. These estimated do not include a depreciation component. NVID Regional Water Supply Project

102 Appendix A Regulatory Overview

103 NID Regional Water Supply Project Technical Memorandum Regulatory Overview Prepared For: Prepared By: Reviewed By: Nevada Irrigation District and City of Lincoln Dave Hunt, P.E. Gerry LaBudde, P.E. 1.0 INTRODUCTION The purpose of this technical memorandum (TM) is to provide an overview of the current and future Federal and State drinking water regulations that will affect the design and operation of the new WTP. The regulations presented include: Surface Water Treatment Rule (SWTR) Interim Enhanced Surface Water Treatment Rule (IESWTR) Long Term 1/2 Enhanced Surface Water Treatment Rule (LT1ESWTR/LT2ESWTR) Stage 1/2 Disinfectants/Disinfection Byproducts Rule (D/DBPR) Filter Backwash Recycling Rule (FBRR) California Code of Regulations, Title 22 California Regulations Related to Drinking Water 2.0 SURFACE WATER TREATMENT RULE The SWTR, promulgated in June 1989, applies to all public water systems using surface water or groundwater under the direct influence (GWUDI) of surface water as water sources. It established maximum contaminant level goals (MCLG) of zero for Giardia, viruses and Legionella. It includes the following treatment technique requirements to reduce exposure to these pathogenic microorganisms: 1. Filtration, unless specific avoidance criteria are met; 2. Maintenance of the disinfectant residual in the distribution system; 3. Removal and/or inactivation of 3-log (99.9%) of Giardia and 4-log (99.99%) of viruses; NVID Appendix A-1 Regional Water Supply Project

104 Regulatory Overview 4. Maximum allowable turbidity in the combined filter effluent of the 5 NTU and 95 th percentile combined filter effluent turbidity of 0.5 NTU or less for plants using conventional treatment or direct filtration; and 5. Watershed protection and source water quality requirements for unfiltered public water systems (PWS). Treatment under the SWTR is required to be accomplished through a combination of filtration and disinfection. The regulation allows a treatment credit of 99.7% (2.5 log) removal of Giardia cysts and a 99% (2 log) removal of enteric viruses, if the filtered water turbidity is equal to or less than 0.5 NTU for 95% of the time. Disinfection is to be used to achieve the remainder of the removal/inactivation requirement, 0.5- log of Giardia and 2-log for viruses. Appropriate disinfection is based upon the product of the disinfectant residual concentration and the effective disinfectant contact time (CT). The CT required is a function of the type of disinfectant, residual concentration, water temperature, and ph. The SWTR also requires that the filtration rates for direct and conventional filtration processes not exceed 6.0 gpm/sf. However, filtration rates of up to 7.5 gpm/sf for deep bed, dual or mixed media filters that operate under gravity flow conditions when performance testing proves such conditions can meet the water quality requirements. Finally, the SWTR also requires that systems demonstrate, by continuous monitoring and recording, that a disinfectant residual of at least 0.2 mg/l is continuously maintained in water delivered to the distribution system. 3.0 INTERIM ENHANCED SURFACE WATER TREATMENT RULE The IESWTR, promulgated in December 1998, applies to PWSs serving at least 10,000 people and using surface water or GWUDI sources. Key provisions established by the IESWTR include the following: 1. An MCLG of zero for Cryptosporidium; 2. Cryptosporidium removal requirements of 2-log (99 percent) for PWSs that filter; 3. More stringent combined filter effluent turbidity performance standards of 1.0 NTU as a maximum and 0.3 NTU or less at the 95th percentile monthly for treatment plants using conventional treatment or direct filtration; 4. Requirements for individual filter turbidity monitoring, including turbidity not to exceed 1.0 NTU based on 2 consecutive measurements (at 15 minute intervals), andless than 0.5 NTU after the first 4 hours of filter operation after a backwash; 5. Disinfection benchmark provisions to assess the level of microbial protection that PWSs provide as they take steps to comply with the new DBP standards; NVID Appendix A-2 Regional Water Supply Project

105 Regulatory Overview 6. Inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered PWSs; 7. Requirements for covers on new finished water storage facilities; and 8. Sanitary surveys for all surface water systems regardless of size. The regulation allows for a 2-log Cryptosporidium removal credit for conventional and direct filtration plants that meet the turbidity performance standards indicated in item 3 above. For PWSs using alternative filtration technologies, such as membranes, no prescribed treatment credit is given because the performance of these processes is specific to individual products. Systems must also develop a disinfection profile unless they can demonstrate that their TTHM and HAA5 levels are less than mg/l and mg/l (80% of the MCL), respectively. The LT1ESTWR has similar requirements for systems serving less than 10,000 people. 4.0 LONG TERM 2 ENHANCED SURFACE WATER TREATMENT RULE The LT2ESTWR, promulgated in January 2006, supplements existing SWTR regulations and targets PWSs with a higher potential risk from Cryptosporidium. The LT2ESWTR was developed in conjunction with the Stage 2 D/DBPR. The LT2SWTR requires the following for systems serving at least 10,000 people: 1. Initial source water monitoring for Cryptosporidium for a duration of two (2) years. The purpose of the monitoring is to determine if additional removal/inactivation requirements will be required to for Cryptosporidium. 2. Additional treatment requirements for filtered public water systems will be based on the Cryptosporidium monitoring results and the resulting Risk Bin classification as shown in Table 1. Systems may substitute previously collected equivalent data (in lieu of new monitoring) that meets the monitoring requirements in the LT2ESWTR. Systems that currently provide the maximum level of treatment required under the Rule (5.5 log removal) are not required to perform any additional monitoring or disinfection profiling. Cryptosporidium Concetration (oocysts/l) Table 1 Bin Classification for Filtered Systems Risk Bin Classification Additional Cryptosporidium Treatment Required Conventional Filtration < Bin 1 No additional treatment required to < 1.0 Bin 2 1 log (total 4-log) 1.0 to < 3.0 Bin 3 2 log (total 5-log) 3.0 Bin log (total 5.5-log) NVID Appendix A-3 Regional Water Supply Project

106 Regulatory Overview 3. A second round of monitoring beginning six years after the initial system classification. 4. If any system plans to make a significant change in its disinfection process, development of disinfection profiles of microbial inactivation levels for Giardia and viruses are required along with calculation of a disinfection benchmark required. Conventional treatment plants in compliance with the IESWTR or LT1ESWTR requirements (i.e. 0.3 NTU in 95% of samples taken) receive a prescribed 3-log Cryptosporidium treatment credit toward the total bin treatment requirements. For PWSs using alternative filtration technologies, such as membranes, no prescribed treatment credit is given because the performance of these processes is specific to individual products. The LT2ESWTR also includes a variety of treatment and control options, the microbial toolbox, that systems can implement to comply with additional treatment requirements. Options include source protection and management programs, prefiltration processes, treatment performance programs, additional filtration components, and disinfection inactivation technologies. PWSs that fall into Bin 3 or Bin 4 classifications must achieve at least 1-log of required treatment using ozone, chlorine dioxide, UV, membranes, bag filtration, cartridge filtration or bank filtration. 5.0 STAGE 1 DISINFECTANTS AND DISINFECTION BYPRODUCTS RULE The Stage 1 D/DBPR, promulgated in December 1998, applies to PWSs that add a disinfectant to any part of the treatment process. The purpose of the Stage 1 D/DBPR is to reduce public exposure to DBPs, specifically four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane, and bromoform), bromate, and chloride and five haloacetic acids (dichloroacetic, trichloroacetic, monochloroacetic, monobromoacetic and dibromoacetic acids). The Stage 1 D/DBPR includes the following requirements: MCLs for some known DBPs to be determined on a system-wide running annual average (RAA): Revised MCL for total trihalomethanes (TTHMs) of 80 μg/l. TTHM is defined as the sum of the concentrations for chloroform, bromodichloromethane, dibromochloromethane and bromoform. New MCL for five of the nine haloacetic acids (HAA5) of 60μg/L. HAA5 is defined as the sum of concentrations for monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid. A maximum residual disinfectant level (MRDL) for chlorine (4.0mg/L). However, the federal regulations indicate that chlorine MRDL may be exceeded in the distribution system for a time necessary to protect public health, to address specific microbiological contamination problems (e.g. cross contamination events or raw water contamination caused by circumstances such as, but not limited to, distribution line breaks, storm runoff events, source water contamination events, or cross-connection events). NVID Appendix A-4 Regional Water Supply Project

107 Regulatory Overview A treatment technique requirement for removal of DBP precursor material to reduce formation of DBPs. Water systems using conventional treatment are required to remove specific percentages of natural organic materials, as measured by total organic carbon (TOC) that may react and form DBPs unless the water system complies by meeting one of six alternative criteria: 1. The system s source water TOC level is less than 2.0 mg/l calculated quarterly as a RAA; 2. The system s treated water TOC is less than 2.0 mg/l calculated quarterly as a RAA; 3. The systems: Source water TOC level is less than 4.0 mg/l, calculated quarterly as a RAA Source water Alkalinity is greater than 60 mg/l (as CaCO 3 ) calculated quarterly as a RAA. Either the TTHM or HAA5 RAAs are no greater than 40 µg/l and 30 µg/l respectively, or prior to the effective date for compliance, the system has made a clear and irrevocable financial commitment to use technologies to limit levels of TTHMs and HAA5 to no more than 40 µg/l and 30 µg/l respectively. 4. The TTHM and HAA5 RAAs are no greater than 40 µg/l and 30 µg/l, respectively, and the system uses only chlorine for primary disinfection and maintenance of a residual in the distribution system. 5. The systems source water Specific Ultraviolet Absorption at 254 nanometers (SUVA) prior to any treatment and measured monthly is less than or equal to 2.0 L/mg-m calculated quarterly as a RAA. 6. The systems finished water SUVA is less than or equal to 2.0 L/mg-m calculated quarterly as a RAA. Monitoring, reporting, and public notification requirements for the constituents subject to the new MCLs and MRDLs. 6.0 STAGE 2 DISINFECTANTS AND DISINFECTION BYPRODUCTS RULE The Stage 2 D/DBPR, promulgated in January 2006 alongside the LT2ESWTR, applies to all systems that add a disinfectant other than UV or deliver water that has been treated with a disinfectant other than UV. The Stage 2 D/DBPR includes a new method of determining compliance with TTHMs and HAA5s. In addition to compliance with the system-wide RAA MCLs in Stage 1 Rule, compliance will also be required at each monitoring location based on locational running annual average (LRAA). Under the Stage 2 Rule, PWSs are required to perform an initial distribution system evaluation (IDSE). An IDSE consists of either a standard monitoring program or a system-specific study. NVID Appendix A-5 Regional Water Supply Project

108 Regulatory Overview The purpose of the IDSE is to determine the compliance monitoring locations that contain high TTHM and HAA5 levels. In addition, the Stage 2 DBP Rule requires that NID comply with: A LRAA MCL for TTHMs of 80 µg/l at each monitoring location identified in the IDSE (in addition to the system-wide RAA MCL of 80 µg/l under the Stage 1 DBP Rule). A LRAA MCL for HAA5 of 60 µg/l at each monitoring location identified in the IDSE (in addition to the system-wide RAA MCL of 60 µg/l under the Stage 1 DBP Rule). 7.0 FILTER BACKWASH RECYCLING RULE (FBRR) The FBRR, promulgated in June 2001, addresses filter backwash water and two additional recycle streams of concern, sludge thickener supernatant and liquids from dewatering processes. The FBRR also establishes reporting and recordkeeping requirements for recycle practices that allow regulators to better evaluate the impact of recycle practices on overall treatment plant performance. The FBRR does not specifically state a maximum return flow based on a percentage of the plants approved operating capacity. The FBRR consist of three distinct components: 1. Requires a water system to notify the State about its recycle practices if it operates a conventional or direct filtration plant to include the following information: A plant schematic showing the origin of all recycle streams, the hydraulic conveyance used to transport the streams, and the location where the recycled streams enter the treatment process; Typical recycle flow, highest observed plant flow experienced the previous year, and design flow for the plant; The State approved operating capacity for the plant, if the State has made such a determination. 2. To obtain the Cryptosporidium removal credit as indicated in the LT1ESWTR and LT2ESWTR, the FBRR requires that spent filter backwash water, thickener supernatant, or liquids from dewatering processes to be returned through all the processes of a system s conventional of direct filtration system. 3. A system must collect and retain the following information for review and evaluation by the State: A copy of the Recycle Notification Form; A list of all recycle flows and the frequency at which they are returned; Average and maximum backwash flow rates through the filters and the average and maximum duration of the filter backwash process; NVID Appendix A-6 Regional Water Supply Project

109 Regulatory Overview Typical filter run length and a written summary of how filter run length is determines (e.g. headloss, turbidity, time, etc.); If applicable, the type of treatment provided for the recycle stream before it reenters the filtration process; and If applicable, data about the physical dimensions of the equalization and/or treatment units, typical and maximum hydraulic loading rates, types of treatment chemicals used, average dose of chemicals, frequency of chemical addition, and frequency of solids removal. 8.0 CALIFORNIA CODE OF REGULATIONS, TITLE 22 CALIFORNIA REGULATIONS RELATED TO DRINKING WATER 8.1. CALIFORNIA SWTR The California SWTR is defined in Title 22, Chapter 17 of the California Code of Regulations (CCR) and requires water suppliers using surface water to provide multi-barrier treatment necessary to protect users from the adverse health effects of microbiological contaminants and to comply with performance standards for filtration and disinfection. The California SWTR contains the similar requirements as the IESWTR for systems serving greater than 10,000 people as presented in Section 3.0 of this TM CALIFORNIA D/DBPR The California D/DBPR is defined in Title 22, Chapter 15.5 of the CCR. California D/DBPR compliance is based on the same criteria as the Stage 1 D/DBPR as presented in Section 5.0 of this TM, including monitoring locations and frequencies, treatment techniques for control of DBP precursors, and reporting and recordkeeping. Monitoring for systems serving greater than 10,000 people requires a minimum of four samples per quarter per treatment plant. The monitoring locations shall provide that at least 25 percent of the samples be taken at points representing maximum residence time in the water distribution system. The remaining samples are taken at locations in the system that represent at least average residence time. Systems may reduce monitoring if one years worth of monitoring results indicate TTHM mg/l and HAA mg/l based on running annual averages CALIFORNIA FILTER BACKWASH RECYCLE REGULATIONS California s regulations regarding filter backwash recycle are included in of the SWTR. The California regulation is similar to the FBRR as presented in Section 7.0 of this TM DESIGN STANDARDS FOR NEW TREATMENT PLANTS The regulatory requirements of the Title 22, Chapter 16 California Waterworks Standards, defines the design standards for a new WTP. The significant components of these requirements are as follows: NVID Appendix A-7 Regional Water Supply Project

110 Regulatory Overview All new filtration facilities be designed and constructed to achieve an average daily effluent turbidity goal of 0.2 NTU when using conventional filtration; Provide filter-to-waste for each filter unit or addition of coagulant chemicals to the water used for backwashing; Provide solids removal treatment for filter backwash water if it is recycled into the treatment process CDPH TREATMENT GUIDELINES AND CRYPTOSPORIDIUM ACTION PLAN CDPH treatment guidelines require additional log removal/inactivation of both Giardia and virus as shown in Table 2 based on raw water total coliform concentrations. Table 2 CDPH Source Water Quality Guidelines for Log Removal/Inactivation Total Coliform Concentration Log Removal Requirements (Median Monthly MPN/100 ml) Giardia Virus <1, >1,000-10, >10, , In 1995, the California Department of Health Services adopted a Cryptosporidium Action Plan intended to facilitate comprehensive compliance with the California SWTR. Some of the information in Action Plan is now only of historical interest. Since 1995, federal rules have been adopted to address Cryptosporidium, including the IESWTR, LT1ESWTR, and LT2ESWTR. Key provisions of the Action Plan as they relate to optimizing treatment at a WTP include: Effluent turbidity goal of 0.1 NTU; Establishing procedures for optimizing the coagulation/flocculation/sedimentation processes to enable maximum turbidity removal with a turbidity goal of 1 to 2 NTU in the effluent of the sedimentation basins at all times; Turbidity monitoring of individual filters; Optimizing the performance of filter backwash recycle and setting an operational gaol of less than 2.0 NTU for the effluent of a plant s reclaimed backwash water and sludge reclamation systems. NVID Appendix A-8 Regional Water Supply Project

111 Appendix B Disinfection Strategies

112 NID Regional Water Supply Project Technical Memorandum Disinfection Strategies Prepared For: Prepared By: Reviewed By: Nevada Irrigation District and City of Lincoln David Hunt, P.E. Gerry LaBudde, P.E. 1.0 INTRODUCTION This section provides information about the overall Project as it relates specifically to the background, purpose, and scope of the disinfection process strategy. 1.1 BACKGROUND To address the projected demand for the treated water in the City of Lincoln (the City) and Nevada Irrigation District (the District), the District and the City joined cooperatively and selected to perform a study to evaluate and select a site for a new regional water treatment plant (WTP) facility. The results were presented in the Lincoln Area Water Treatment Plant Planning and Site Study, (ECO:LOGIC, August 2005 [Siting Study]). Subsequent to the Siting Study, ECO:LOGIC was selected to prepare a planning and predesign study for the NID Regional Water Supply Project (Project). This study was commissioned by the District to further investigate the feasibility of the Project, and to recommend the location, size, and configuration of Project components. The purpose of the Planning and Predesign Study is to recommend feasible alternatives to the Project as a whole, as well as alternatives for individual Project components, and then incorporate these recommendations into a proposed Project description for use in the Draft Environmental Impact Report (DEIR). 1.2 EVALUATION APPROACH This technical memorandum (TM) focuses on the conclusions of an evaluation of the disinfection processes for the new WTP based on the proposed water treatment process; conventional pretreatment followed by mixed media filtration. The following alternatives are evaluated: 1. Primary and secondary chlorination (chlorine gas, liquid sodium hypochlorite, or onsite generation of sodium hypochlorite) 2. Primary/secondary chlorination followed by secondary ultraviolet (UV) disinfection for Cryptosporidium inactivation NVID Appendix B-1 Regional Water Supply Project

113 Disinfection Strategies 3. Primary ozone disinfection for Cryptosporidium inactivation followed by secondary chlorination The alternative disinfection strategies are evaluated based on a non-economic evaluation (regulatory compliance, disinfection effectiveness, operational complexity) and an economic evaluation (capital costs, operation and maintenance costs, and 20-year present worth value). The design criteria presented is based on an initial WTP capacity of 10 million gallons per day (MGD) and a build out capacity of 40 MGD. 2.0 REGULATORY DISINFECTION REQUIREMENTS FOR CONVENTIONAL TREATMENT PROCESS Both state and federal regulations dictate the degree of disinfection requirements that must be met by the new conventional WTP. The section first summarizes the source water quality parameters that are relevant to selection of the disinfection strategy. Also presented is a discussion of state and federal regulations which will affect the disinfection strategy for controlling Giardia, virus, and Cryptosporidium. 2.1 WATER QUALITY Combie Reservoir is the source of water for the primary water supply, although the location of the diversion point(s) will vary depending on Project phasing related to raw water conveyance and water quality. Diversion points under consideration include the Combie Ophir Phase 1 Canal and the Camp Far West Canal. The diversion of the back-up water supply would be from the Whiskey Diggins Canal. Raw water quality data collected since the start of the Project that are relevant to disinfection are presented in Table 1. Limited historical water quality data is available for these sources; however, beginning in February 2008, monthly samples have been taken from each source for evaluation of several key water quality parameters. A full analysis of the complete water quality data set is presented in a separate TM, Water Quality Evaluation. NVID Appendix B-2 Regional Water Supply Project

114 Disinfection Strategies Water Quality Parameter, Unit of Measurement Table 1 Raw Water Source Quality (a) Primary Water Supply Camp Far West Combie Ophir Back-Up Water Supply Whiskey Diggins Turbidity, NTU Avg Total Organic Carbon, mg/l Avg Temperature, o F Avg Alkalinity, mg/l as CaCO 3 Avg ph, ph units Avg Total Coliform, MPN per 100 ml Avg. 1, ,040 Bromide, mg/l (b) Avg. ND ND ND UV Transmittance, % (b) Avg Cryptosporidium, Total/L (c) Min Max Giardia, Total/L (b) Min Max (a) Samples taken monthly between February 2008 and January 2009 (Camp Far West data provided by NID from January 2007 through January 2008) (b) One sample taken March 2009 (c) Samples taken April 2008 and December REGULATORY REQUIREMENTS Pertinent current and future regulations that may be applicable to disinfection design considerations and operation at the WTP are discussed below Surface Water Treatment Rule California Department of Public Health s (CDPH) Surface Water Treatment Rule (SWTR) requires water suppliers using surface water to provide multi-barrier treatment necessary to protect users from the adverse health effects of microbiological contaminants and to comply with performance standards for filtration and disinfection. Compliance with the requirements of the SWTR is based on :(1) A total of 3-log (99.9 %) reduction of Giardia through filtration and disinfection; and (2) A total of 4-log (99.99 %) reduction of viruses through filtration and disinfection. These requirements are equivalent to the federal SWTR. Also, because the proposed raw water supplies have shown total coliform concentrations exceeding 1,000 MPN/100 ml (Table 1), CDPH treatment guidelines require and additional 1- log removal/inactivation of both Giardia and virus as shown in Table 2. NVID Appendix B-3 Regional Water Supply Project

115 Disinfection Strategies Table 2 CDPH Source Water Quality Guidelines for Log Removal/Inactivation Total Coliform Concentration Log Removal Requirements (Median Monthly MPN/100 ml) Giardia Virus <1, >1,000-10, >10, , Based on CDPH regulation and guidelines, the total removal/inactivation requirements for Giardia and virus are 4.0-log and 5.0-log, respectively. The federal SWTR had been developed in multiple components over the years with the latest regulations adding the removal/inactivation requirements for Cryptosporidium. The Long Term 2 Enhanced SWTR (LT2ESWTR) requires a minimum of 3-log removal/inactivation of Cryptosporidium, with additional treatment required based on raw water quality determined by raw water testing. The treatment requirements under the LT2ESWTR are broken down into bin classifications with treatment of up to 5.5 log reduction required for the poorest source water quality. The bin classification is currently based on intensive source water testing for E. coli, and possibly Cryptosporidium. That testing is anticipated to take place after completion of the predesign. To ensure that the new WTP will meet future regulations, The Project team has decided that the disinfection processes identified in the predesign would be based on a worst case classification of Bin 4. Table 3 provides the bin classifications for conventional treatment as written in the LT2ESWTR. Cryptosporidium Concetration (oocysts/l) Table 3 Treatment Requirements for LT2ESWTR Risk Bin Classification Additional Cryptosporidium Treatment Required Conventional Filtration < Bin 1 No additional treatment required to < 1.0 Bin 2 1 log 1.0 to < 3.0 Bin 3 2 log 3.0 Bin log To satisfy these requirements, a conventional treatment plant receives a 3-log removal credit for Cryptosporidium by meeting turbidity standards. Therefore, up to an additional 2.5-log inactivation by disinfection is required for the NID WTP to meet the Bin 4 requirements. NVID Appendix B-4 Regional Water Supply Project

116 Disinfection Strategies Disinfection Removal/Inactivation Requirements and Credits for the NID WTP Based on the criteria discussed above, Table 4 provides a summary of the removal/inactivation requirements for the NID WTP. Table 4 Regulatory Requirements and Treatment Credit Log Removal/Inactivation Regulatory Requirements Giardia Virus Cryptosporidium SWTR N/A CDPH Source Water Quality Guidelines (based on >1,000 MPN/100 ml total coliform) LT2ESWTR Process Credits N/A N/A N/A Up to 5.5-log (see Table 6) Conventional Filtration Process NID WTP Disinfection Inactivation Requirements Disinfectants/Disinfection Byproducts Rule (D/DBPR) Total organic carbon (TOC) is a measure of organic carbon in water and is recognized as a general indicator of the occurrence of disinfection by-product precursors. Disinfection byproducts are produced when disinfectants like chlorine and ozone react with organic matter in the water. The Stage 1 and Stage 2 D/DBPR are aimed at reducing TOC concentrations in the raw and finished water through treatment, thus reducing the DPB concentrations in the water supplied to customers. The Stage 1 D/DBPR requires systems using surface water and conventional filtration treatment to remove specific amounts of TOC during the treatment process by implementing a treatment technique; enhanced coagulation in this case. TOC removal requirements are based on raw water TOC and total alkalinity as indicated in Table 5. TOC and alkalinity compliance data is based on monthly monitoring, and is calculated based on a running annual average (RAA) of the quarterly averages. Based on the compliance monitoring requirements, the water quality sampling program showed quarterly RAA s for TOC and total alkalinity for the potential raw water sources to be as follows: Camp Far West TOC = 3.65 mg/l, alkalinity = 43 mg/l as CaCO3 Combie Ophir Phase 1 TOC = 1.82 mg/l, alkalinity = 19 mg/l as CaCO3 Whiskey Diggins (backup supply) TOC = 2.23 mg/l, alkalinity = 30 mg/l as CaCO3) NVID Appendix B-5 Regional Water Supply Project

117 Disinfection Strategies Table5 Required Percent Removal of TOC by Enhanced Coagulation using Conventional Filtration Treatment Source Water TOC (mg C/L) % TOC Reduction Requirement w/ Various Source Water Alkalinity (mg CaCO 3 /L) 0-60 > >120 > % 25.0% 15.0% > % 35.0% 25.0% > % 40.0% 30.0% The Stage 1 rule also provides alternative compliance criteria that could be met in lieu of the treatment technique. Two of those criteria are relevant to the NID WTP: Source water TOC is less than 2.0 mg/l Treated water TOC is less than 2.0 mg/l Based on the water quality, the NID WTP would be required to remove 35% of the raw water TOC by enhanced coagulation for the Camp Far West and Whiskey Diggins water supplies. The Combie Ophir Phase 1 supply would require no further TOC reduction. 3.0 DISINFECTION STRATEGIES AND DESIGN CRITERIA At the new WTP, the primary disinfectant(s) that may be used to satisfy current regulatory requirements are free chlorine (in the form of liquid chlorine, gas chlorine, or on-site generated liquid chorine) or ozone. As the LT2ESWTR requirements for Cryptosporidium removal/inactivation are imposed on the WTP, free chlorine alone will not be able to meet the inactivation criteria of up to 2.5-Log Cryptosporidium inactivation. Currently available best alternative disinfectants that are evaluated for Cryptosporidium inactivation are ozone and UV disinfection. In the following sub-sections, various disinfectants are compared for the following scenarios: 1. Primary and secondary chlorination (chlorine gas, liquid sodium hypochlorite, or onsite generation of sodium hypochlorite) 2. Primary ozone disinfection for Cryptosporidium inactivation followed by secondary chlorination 3. Primary/secondary chlorination followed by secondary ultraviolet (UV) disinfection for Cryptosporidium inactivation Based on the water quality data for the potential water sources, the following criteria were used for disinfection evaluation: Raw water design temperature: 41 F (5 C) Raw water ph: 8.5 NVID Appendix B-6 Regional Water Supply Project

118 Disinfection Strategies The temperature and ph criteria listed above represent the worst case scenario based on the available water quality data. For free chlorine, the efficacy of disinfection increases with increasing water temperature and decreasing ph, thus higher CT values are required at higher ph, lower temperature conditions (CT is defined in the SWTR as residual disinfectant concentration [C, mg/l] multiplied by contact time [T, min] and provides for minimum disinfectant residual concentrations and contact times to meet inactivation requirements for virus, Giardia, and Cryptosporidium). Ozone is not affected by ph and the SWTR CT tables require higher CT values for reduced temperature conditions. UV disinfection is not dependent on ph or temperature of the water. CT values are represented by UV dose (mj/cm 2 ) as set forth in the LT2ESWTR for the specific pathogen to be inactivated. CT values are presented for each disinfection strategy. The CT requirements are used to provide minimum clearwell sizing to meet the specific inactivation requirements for Giardia and virus. Secondary disinfection requirements for Cryptosporidium are provided by contactors required for ozone or UV disinfection. It should be noted that treated water storage facilities will be large enough to meet all CT requirements defined herein. 3.1 PRIMARY AND SECONDARY CHLORINATION DISINFECTION Free chlorine can satisfy the disinfection requirements for Giardia and virus, but not Cryptosporidium. According to the regulatory requirements presented in Table 4, 1.5-log Giardia and 3.0-log virus inactivation would be required by disinfection. Disinfection by free chlorine can be achieved using either gaseous chlorine or liquid sodium hypochlorite. A brief discussion of these chlorination methods are presented below Chlorine Gas The chlorination facility for water treatment consists of chlorine supply and chlorine gas feed systems. Chlorine is packaged in special steel containers, usually 150 pound or 1 ton cylinders and is generally stored in a separate room from the feed equipment. The Uniform Fire Code contains detailed requirements for chlorine gas storage. The major requirement under this rule is for a treatment system that can either neutralize or contain the contents of a release of one cylinder (scrubber system). The treatment system must also process all ventilation exhaust from the gas storage area. Equipment to feed chlorine gas is designed to work either under pressure or under vacuum, with vacuum systems by far the most common in water treatment. The vacuum operated systems offer greater safety in the operation of the equipment and handling of chlorine gas, and also provide for greater versatility in the application and control of chlorine dosage. NVID Appendix B-7 Regional Water Supply Project

119 Disinfection Strategies Liquid Sodium Hypochlorite Liquid sodium hypochlorite is delivered commercially at 12.5% strength (household bleach is 5.25%), with approximately 1 pound of available chlorine per gallon of solution. Hypochlorite is classified as a corrosive liquid and is most often stored in polyethylene tanks. At the quantities used for the new WTP, hypochlorite would be delivered by bulk tanker trucks which carry as much as 4,000 gallons of solution. The stability of hypochlorite solutions are greatly affected by heat and light. For this reason, it is necessary to store solutions in a climate controlled environment. The storage facility must be capable of containing hypochlorite spills for the entire tank contents. Sodium hypochlorite systems are simple to operate, using liquid chemical feed pumps that can be controlled to provide the required chlorine dosage. However, concentrated hypochlorite has the disadvantage that operators must handle a corrosive and potentially dangerous chemical, requiring the use of gloves, apron, and face shield during handling On-Site Generation of Sodium Hypochlorite Sodium hypochlorite can also be generated on-site using electricity and salt to produce a 0.8% chlorine solution. On-site generation has the principle advantage of eliminating the hazardous materials handling requirements. Also, a 0.8% hypochlorite solution is much more stable than a 12.5% solution. Equipment used in on-site generation includes a water softener, storage tanks for the sodium hypochlorite produced, and salt storage and saturator equipment. Chemical feed pumps are used to feed the liquid sodium hypochlorite solution. The major disadvantages of on-site generation are the large salt and electricity requirements. Generally, the electricity requirement is 2 kilowatt-hours (kwh) for each pound of available chlorine produced. The salt requirement is about 3 pounds of high quality salt per pound of available chlorine produced. For a system of the size necessary for the NID WTP, at buildout capacity of 40 MGD, salt requirements amount to between 3,000-6,000 pounds per day, depending on chlorine dose required Design Criteria In this option, free chlorine in the form of chlorine gas or liquid sodium hypochlorite would be used throughout the treatment process. Use of free chlorine by itself will not satisfy the Cryptosporidium inactivation requirements of the LT2ESWTR, but it will satisfy all other SWTR requirements for Giardia and virus. Chlorination would occur at the following locations (chlorine dosages are assumed maximums and are used for facility sizing): Prechlorination (headworks) : 1.0 mg/l, maximum Pretreatment: 1.0 mg/l, maximum NVID Appendix B-8 Regional Water Supply Project

120 Disinfection Strategies After filter and before clearwell: 2.0 mg/l, maximum Before distribution: as needed to maintain minimum free residual of 0.2 mg/l in distribution system, estimated at 1.0 mg/l, maximum). The total plant chlorine dose in this case is 5 mg/l, which amounts to a daily chlorine demand of approximately 500 lbs/day at an initial plant capacity of 10 MGD. Based on a water temperature of 5 C and a ph of 8.5, the CT requirements are shown in Table 6. Log Inactivation Required Table 6 CT Requirements for Free Chlorine Virus 3-log Free Chlorine CT Values Giardia 1.5-Log CT, mg-min/l As shown in Table 6, the CT value for Giardia inactivation is orders of magnitude higher than the virus value. Thus, clearwell volume for contact time would be based on Giardia inactivation. In Table 7, a summary of the clearwell volumes are estimated for the WTP capacities shown, and are based on a baffle factor (T 10 /T) of 0.5 and a chlorine residual leaving the clearwell of 0.75 mg/l. The baffle factor defines how well water is mixed within a tank, thus increasing the amount of contact time the chlorine has with the water. A baffle factor of 0.5 represents an average condition. Table 7 Clearwell Size for Free Chlorine Contact Disinfection (1.5-Log Giardia inactivation) Design Capacity (Million Gallons per Day) Required Clearwell Volume (Million Gallons) PRIMARY OZONE/SECONDARY CHLORINATION Ozonation in drinking water treatment is used to satisfy a number or treatment goals, including: Disinfection and algae control Oxidation of inorganic pollutants Oxidation of organic micropollutants Improvement of coagulation NVID Appendix B-9 Regional Water Supply Project

121 Disinfection Strategies The application of ozone for primary disinfection is most common at the head of the plant, before coagulation/flocculation. For this evaluation, ozone would used as a primary disinfectant to satisfy Cryptosporidium inactivation requirements followed by free chlorine to meet distribution system residual chlorine requirements. Using ozone as the primary disinfectant would greatly reduce the chlorine requirements for the WTP. A reduction in chlorine usage would result in reduced formation potential for TTHM and HAA5 DBP s. The regulated DBP formed by using ozone is bromate, which is produced by the reaction of ozone and bromide in the raw water source. Water quality sampling performed on the potential sources indicated non-detect levels of bromide, therefore greatly reducing the potential for the formation of bromate in the treated water Design Criteria In this disinfection strategy, ozone would be used for the additional 2.5-Log Cryptosporidium inactivation requirement should the source water be classified as Bin 4 under the LT2ESWTR. When ozone is used for disinfection, all log inactivation requirements for virus, Giardia, and Cryptosporidium would be achieved with ozone alone. The role of free chlorine would be limited to maintaining disinfectant residual entering the distribution system as required by the SWTR. Ozone would be used as the primary disinfectant and chlorine would be added after filtration at an approximate maximum dose of 1.5 mg/l, which amounts to a daily chlorine demand of approximately 125 lbs/day at 10 MGD plant capacity. Ozonation would be performed prior to coagulation/flocculation at an estimated maximum dose of 5 mg/l. This equates to an ozone demand of approximately 500 lbs O 3 /day at 10 MGD plant capacity. Based on a water temperature of 5 C, the CT requirements are shown in Table 8. Log Inactivation Required Table 8 CT Requirements for Ozone Ozone CT Values Virus Giardia Cryptosporidium 3-log 1.5-log 2.5-log CT, mg-min/l As shown in Table 6, the CT value for Cryptosporidium inactivation is orders of magnitude higher than for virus and Giardia. Thus, contactor basin volume would be based on Cryptosporidium inactivation. It will necessary to conduct bench and pilot scale studies to determine specific ozone dose and contactor requirements. Bench and pilot scale studies would be necessary to determine ozone demand and ozone decay rates. This data would provide an ozone residual profile for which to NVID Appendix B-10 Regional Water Supply Project

122 Disinfection Strategies size the contactor to meet CT requirements. Estimated contactor basin size and geometry is estimated based on the following criteria: CT = 40 mg-min/l for Cryptosporidium inactivation Baffle factor T 10 /T = 0.6 T 10 = 20 min. (basin hydraulic retention time = 33 min.) Ozone initial dose = 3 mg/l Based on these criteria, an approximate basin size would be 200,000 gallons at 10 MGD WTP capacity. Approximate dimensions of the contactor basin are 50 feet long by 30 feet wide with a water depth of 20. Subsequent WTP expansions would increase the basin size accordingly (e.g. 20 MGD would require 400,000 gallon contactor). A building is also required to house the ozone generation equipment. The approximate ozone equipment building size for the initial 10 MGD plant capacity is 2,500 ft SECONDARY ULTRAVIOLET DISINFECTION WITH PRIMARY/SECONDARY CHLORINATION UV disinfection is an emerging disinfection technology in the drinking water industry and is expected to increase in use with the requirements set forth in the LT2ESWTR. UV disinfection is known to be very effective for inactivation of Giardia and Cryptosporidium and would be used as a secondary disinfectant in this case. To meet the virus inactivation requirement, free chlorine would be used with the CT being met in the treated water storage tank(s). UV is a chemical free disinfectant. With the use of UV for secondary disinfection of Giardia and Cryptosporidium, a reduction in the amount of chlorine used for disinfection would be seen. With this reduction also comes a reduction in the formation of DBP s. This, along with the inactivation of Cryptosporidium, is a major advantage to using this disinfection strategy Design Criteria UV disinfection would be used to meet Giardia and Cryptosporidium inactivation requirements. Virus inactivation would be accomplished with free chlorine in the treated water storage tank(s). The UV disinfection would be performed immediately after filtration. Chlorination will occur at the following locations (chlorine dosages are assumed maximums and are used for facility sizing): Pretreatment: 1.0 mg/l, maximum After filter and before clearwell (to meet virus inactivation and distribution system chlorination requirements): 1.5 mg/l, maximum The total plant chlorine dose in this case is 2.5 mg/l, which amounts to a daily chlorine demand of approximately 200 lbs/day at 10 MGD plant capacity. Minimum UV dose requirements required by the LT2ESWTR are summarized in Table 9. As shown, Giardia and Cryptosporidium inactivation with UV can be accomplished with a low UV NVID Appendix B-11 Regional Water Supply Project

123 Disinfection Strategies dose. On the other hand, the UV dose required for virus is close to 19 times that of Cryptosporidium. Actual UV doses would be developed during reactor validation testing as required by the LT2ESWTR. Reactor validation testing establishes the operating conditions under which a reactor can deliver the required UV dose under the range of operating conditions experienced at the WTP. Log Inactivation Required Table 9 UV Dose Requirements UV CT Values Virus Giardia Cryptosporidium 3-Log 1.5-Log 2.5-Log UV Dose, mj/cm The UV irradiation disinfection would be performed in pressurized prefabricated UV reactors with baffles. The UV equipment would be housed in a building downstream of filtration. The estimated footprint for the initial 10 MGD plant capacity is approximately 1,600 ft EVALUATION OF DISINFECTION STRATEGIES This section provides an economic and non-economic evaluation of the disinfection strategies. 4.1 ECONOMIC EVALUATION The economic evaluation compares capital and O&M costs, along with the 20-year present worth associated with the evaluated disinfection strategies for the initial 10 MGD plant capacity. Capital costs include facility, equipment, sitework, and electrical/controls costs. O&M costs include power, chemical, and estimated labor requirements. Detailed costs estimates are provided in Attachment A of the TM. Unit costs for the estimation of power and labor are as follows: Power - $0.10/kwh Labor - $65/hour (all alternatives are estimated based on 400 hours per year operator attention) Clearwell costs are not estimated since more than ample clearwell volume would be provided within the treated water storage tanks(s) to satisfy CT requirements. CT requirements for ozonation and UV disinfection would be satisfied in their respective contactors. Present worth values for the alternatives are also provided and are based on a 20 year time frame at an interest rate of 5.0%. A detailed summary of present worth values is presented in Attachment B of this TM. NVID Appendix B-12 Regional Water Supply Project

124 Disinfection Strategies PRIMARY AND SECONDARY CHLORINATION The estimated capital and O&M costs for gaseous chlorination, liquid chlorine, and on-site generation are presented in Table 10. The estimated capital and O&M costs are based on a total plant chlorine dosage of 5 mg/l (approximately 500 lb/day at 10 MGD, etc.). Criteria used in estimating the costs for each chlorination alternative are as follows: Gas Chlorination - The estimated building footprint for the chlorination equipment and cylinder storage area is750 ft 2 at 10 MGD plant capacity. Chlorine ton cylinder storage is based on a 30 day supply (eight 1 ton cylinders at 10 MGD plant capacity). The chlorine gas scrubber system would be placed outside. Liquid Chlorine - The estimated building footprint for the chemical metering pumps and hypochlorite storage tanks 7,500 gallons each for 30 days storage) is based on 1,500 ft 2 at 10 MGD plant capacity. On-site Generation - The estimated building footprint for the hypochlorite generation equipment and chemical metering pumps is based on 1,000 ft 2 at 10 MGD plant capacity. The bulk salt storage tank(s) would be placed outside and would be sized based on 30 days of storage. The capital costs included items such as equipment, chemical storage tanks, feed pumps, etc. The O&M costs included items such as labor, chemicals, power, maintenance, and electrical power use. Table 10 Capital, O&M, and 20-Year Present Worth Costs for Chlorination Alternatives Description of Alternative Capital O&M ($/yr) Present Worth Gaseous Chlorine $562,500 $75,500 $1.5 million Liquid Chlorine (@12.5% sodium hypochlorite) On-Site Chlorine Generation (@0.8% hypochlorite) $412,500 $149,500 $2.3 million $850,000 $90,000 $2.0 million PRIMARY OZONE/SECONDARY CHLORINATION Table 11 provides the cost estimate for the ozone/chlorination disinfection alternative and is based on utilizing ozone as the primary disinfectant followed by chlorination to meet the distribution system chlorine residual requirements of the SWTR. The estimated ozone dose is 5 mg/l and the estimate chlorine requirement is approximately 150 lbs/day (2 mg/l) at a plant capacity of 10 MGD. Estimated capital and O&M costs are based on the Mitsubishi Electric Power Products ozone system. Costs are provided for the ozone system alone, along with the complete disinfection system of ozone with chlorination. Criteria used in estimating the costs for each alternative are as follows: NVID Appendix B-13 Regional Water Supply Project

125 Disinfection Strategies Ozone The estimated building footprint for the ozone generation equipment is based on 2,500 ft 2 at 10 MGD plant capacity. The liquid oxygen storage tank would be placed outside. The ozone contactor footprint is 200,000 gallons at 30 minutes hydraulic retention time. Gas Chlorination - The estimated building footprint for the chlorination equipment and cylinder storage area is based on 350 ft 2 at 10 MGD plant capacity. Chlorine ton cylinder storage is based on a 30 day supply (three 1 ton cylinders at 10 MGD plant capacity). The chlorine gas scrubber system would be placed outside. Liquid Chlorine - The estimated building footprint for the chemical metering pumps and hypochlorite storage tanks 2,300 gallons each for 30 days storage) is based on 500 ft 2 at 10 MGD plant capacity. On-site Generation - The estimated building footprint for the hypochlorite generation equipment and chemical metering pumps is based on 500 ft 2 at 10 MGD plant capacity. The bulk salt storage tank(s) would be placed outside. Table 11 Capital, O&M, and 20-Year Present Worth Costs for Primary Ozone/Secondary Chlorination Capital Cost($) O&M ($/yr) Present Worth Present Worth, Ozone + Chlorination (a) Ozone $3,650,000 $300,000 $7.4 million Chlorination Gaseous Chlorine $415,000 $41,500 $930,000 $8.3 million Liquid Chlorine (@12.5% sodium hypochlorite) On-Site Chlorine Generation (@0.8% hypochlorite) $141,250 $64,000 $940,000 $8.3 million $415,000 $45,000 $980,000 $8.4 million (a) Calculation is based on present worth cost for ozone plus the respective chlorination alternative SECONDARY ULTRAVIOLET DISINFECTION WITH PRIMARY/SECONDARY CHLORINATION Table 12 provides the cost estimate for the UV/chlorination disinfection alternative and is based on using UV disinfection for the additional 2.5-Log Cryptosporidium inactivation requirements of LT2ESWTR. Virus inactivation would be accomplished with free chlorine in the treated water storage tank(s). The estimated chlorine dose for virus inactivation and distribution system residual is approximately 200 lbs/day (2.5 mg/l). Costs are provided for the UV system alone, along with the complete disinfection system of UV with chlorination. Criteria used in estimating the costs for each alternative are as follows: UV The estimated building footprint for the UV contactors and equipment is based on 1,600 ft 2 at 10 MGD plant capacity. NVID Appendix B-14 Regional Water Supply Project

126 Disinfection Strategies Gas Chlorination - The estimated building footprint for the chlorination equipment and cylinder storage area is based on 400 ft 2 at 10 MGD plant capacity. Chlorine ton cylinder storage is based on a 30 day supply (three 1 ton cylinders at 10 MGD plant capacity). The chlorine gas scrubber system would be placed outside. Liquid Chlorine - The estimated building footprint for the chemical metering pumps and hypochlorite storage tanks 3,750 gallons each for 30 days storage) is based on 750 ft 2 at 10 MGD plant capacity. On-site Generation - The estimated building footprint for the hypochlorite generation equipment and chemical metering pumps is based on 650 ft 2 at 10 MGD plant capacity. The bulk salt storage tank(s) would be placed outside. Table 12 Capital, O&M, and 20-Year Present Worth Costs for Secondary UV with Primary/Secondary Chlorination Capital Cost($) O&M ($/yr) Present Worth Present Worth, UV + Chlorination UV System $1,350,000 $51,000 $2.0 million Chlorination Gaseous Chlorine $440,000 $51,500 $1.1 million $2.9 million Liquid Chlorine (@12.5% sodium hypochlorite) On-Site Chlorine Generation (@0.8% hypochlorite) $212,500 $88,000 $1.3 million $3.3 million $530,000 $58,000 $1.2 million $3.2 million (a) Calculation is based on present worth cost for ozone plus the respective chlorination alternative 4.2 NON-ECONOMIC EVALUATION The non-economic evaluation presents key advantages/disadvantages for each of the disinfection strategies PRIMARY AND SECONDARY CHLORINATION Free chlorine is a potent disinfection agent with a long history of use in potable water treatment, especially effective in inactivation of Giardia and virus. Table 13 summarizes the key issues associated with the use of free chlorine as the disinfection strategy. NVID Appendix B-15 Regional Water Supply Project

127 Disinfection Strategies Table 13 Non-Economic Evaluation of Chlorination Alternatives Gas Chlorine Sodium Hypochlorite On-Site Generation Advantages Disadvantages Advantages Disadvantages Advantages Disadvantages Simple to operate and maintain Excellent for virus and Giardia NID existing WTP s utilize gas chlorination with scrubber system Smallest footprint of chlorination options Least cost of chlorination options Not effective for Cryptosporidium, secondary disinfectant required Gas chlorination system requires chlorine scrubber system Compliance with UFC Risk Management Prevention Program Higher potential for formation of elevated levels of DBP/s Simple to operate and maintain Excellent for virus and Giardia NID existing WTP s utilize liquid chlorine Not effective for Cryptosporidium, secondary disinfectant required Higher potential for formation of elevated levels of DBP/s High O&M due to sodium hypochlorite costs Excellent for virus and Giardia NID existing WTP s utilize liquid, gas, or on-site generation NID existing WTP s utilize on-site generation, although on a much smaller scale Non-hazardous material at hypochlorite concentration of 0.8% Not effective for Cryptosporidium, secondary disinfectant required On-site generation system requires significant quantities of power and salt Higher potential for formation of elevated levels of DBP/s Largest footprint of chlorination options NVID Appendix B-16 Regional Water Supply Project

128 Disinfection Strategies PRIMARY OZONE/SECONDARY CHLORINATION Ozone is a very strong oxidant and powerful disinfectant with the ability to meet the inactivation requirements for Giardia, Cryptosporidium and virus. Table 14 summarizes the key issues associated with the use of primary ozone/secondary chlorination as the disinfection strategy. Table 14 Non-Economic Evaluation for Primary Ozone/Secondary Chlorination Advantages Ozone excellent for Giardia, Cryptosporidium, and virus Brominated DBP s not expected based on nondetect bromide water quality result Reduced chlorinated DBP s based on reduced chlorine use Effective at potential taste and odor control as well as enhanced coagulation properties Disadvantages Operationally complex compared to chlorination High power requirement for ozone generation NID has no operating experience using ozone Large footprint requires ozone contactor SECONDARY ULTRAVIOLET DISINFECTION WITH PRIMARY/SECONDARY CHLORINATION UV is a very powerful disinfectant with the ability to meet the inactivation requirements for Giardia and Cryptosporidium. Virus inactivation requirements would be met by secondary free chlorine disinfection and CT in the finished water storage tank(s). Table 15 summarizes the key issues associated with the use of primary UV as the disinfection strategy. Table 15 Non-Economic Evaluation for Secondary UV with Primary/Secondary Chlorination Advantages Operationally simple but more maintenance required than chlorination in the form of lamp cleaning/replacement Chemical free disinfectant Excellent for Giardia, Cryptosporidium UV disinfection does not form DBPs Reduced chlorinated DBP s based on reduced chlorine use Small footprint compared to ozone Disadvantages High power requirement NID has no operating experience using UV Free chlorine disinfection required for virus inactivation High power requirement 5.0 SUMMARY AND RECOMMENDATIONS The NID WTP predesign disinfection strategy will not only meet the requirements of the current SWTR, but also the anticipated Cryptosporidium inactivation requirements of the LT2ESWTR. For the purpose of developing the maximum footprint for the new WTP, the disinfection system predesign includes provisions to meet all current and future regulations. This means predesign of a system that will meet the Bin 4 classification for Cryptosporidium removal/inactivation pursuant to the LT2ESWTR. Chlorination alone will not satisfy the log inactivation NVID Appendix B-17 Regional Water Supply Project

129 Disinfection Strategies requirements for Cryptosporidium. Based on the detailed evaluation of disinfection strategies presented in the TM, the recommended disinfection strategy is secondary UV disinfection with primary/secondary chlorination. UV is recommended for the following reasons: Very effective in meeting Giardia and Cryptosporidium inactivation requirements Much lower capital, O&M, and 20-year present worth costs than ozone Much smaller footprint than ozone UV does not form DBP s For primary/secondary chlorination, sodium hypochlorite is the recommended disinfectant for the following reasons: Reduced potential safety hazards with the delivery, handling, and storage than chlorine gas 20-year present worth values comparable to chlorine gas and on-site generation Lowest capital cost of chlorination options No chlorine gas scrubber system and compliance with UFC RMPP National trend for chlorination practice Design criteria for the recommended disinfection strategy are presented in Table 16. Table 16 Design Criteria for Secondary UV with Primary/Secondary 10 MGD Plant Capacity UV Design Criteria Target log inactivation for Giardia Target log inactivation for Cryptosporidium UV dose required for Cryptosporidium inactivation, mj/cm 2 (a) Chlorination Design Criteria Target log inactivation for virus CT required (ph=8.5, Temp.=5ºC), mg-min/l Baffling factor in finished water storage tank T 0.75 mg/l residual, min. Hydraulic detention time T, min Volume required for CT, gallons Chlorine Dose, mg/l, maximum o Pretreatment o Post Filtration Chlorine Dose, 10 MGD , (a) Actual applied UV dose will be based on validation testing as required by the LT2ESWTR NVID Appendix B-18 Regional Water Supply Project

130 Attachment A Cost Estimate Details

131 Gaseous Chlorine Summarized Project Cost Quantity Unit Price per Unit Total Cost Gas Chlorine Feed Equipment (10 MGD) 1 LS $ 75,000 $ 75,000 Chlorine Gas Scrubber System for Ton Cylinder 1 LS $ 200,000 $ 200,000 Storage and Equipment Building (750 sq. ft.) 1 LS $ 150,000 $ 150,000 Mechanical/Electrical Installation 1 LS $ 137,500 $ 137,500 - $ - Total Capital Cost $ 562,500 Annual Operating Costs Gaseous Chlorine 500 lb/day $ 0.25 $ 45,000 Parts/Reagents 1 LS $ 4, $ 4,500 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 75,500

132 Sodium Hypochlorite 12.5% Summarized Project Cost Quantity Unit Price per Unit Total Cost Chemical Feed Pumps, 6 total (2 for each feed location - headworks, pre-coagulation, post filtration) 1 LS $ 50,000 $ 50,000 Hypochlorite Storage Tanks 7,500 gallons) 2 EA $ 15,000 $ 30,000 Equipment Building (1,500 sq. ft.) 1 LS $ 300,000 $ 300,000 Mechanical/Electrical Installatoin 1 LS $ 32,500 $ 32,500 Total Capital Cost $ 412,500 Annual Operating Costs Sodium Hypochlorite 12.5% 500 gal/day $ 0.65 $ 118,625 Power (Chemical feed pumps, etc) 1 LS $ 5,000.0 $ 5,000 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 149,625

133 On-Site Hypochlorite Summarized Project Cost Quantity Unit Price per Unit Total Cost MIOX 500 ppd System 1 LS $ 400,000 $ 400,000 Equipment Building (1,000 sq. ft.) 1 l.s. $ 200,000 $ 200,000 Chemical Feed Pumps, 6 total (2 for each feed location - headworks, pre-coagulation, post filtration) 1 LS $ 50,000 $ 50,000 Mechanical/Electrical Installation 1 LS $ 200,000 $ 200,000 Total Capital Cost $ 850,000 Annual Operating Costs Power (500lb/day x 2KWh) 1,000 kw-hr. $ 0.10 $ 36,500 Salt (3 lbs/lb chlorine x 500 lb/day) 1,500 lbs/day $ 0.05 $ 27,375 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 89,875

134 Primary Ozone/Secondary Chlorination Ozone Quantity Unit Price per Unit Total Cost SMO 700 (1+1, Duty+Standby) for 10 MGD 1 LS $ 1,100,000 $ 1,100,000 Equipment Room (2,500 sq. ft.) 1 LS $ 500,000 $ 500,000 Ozone Contactor 1 LS $ 1,500,000 $ 1,500,000 Mechanical/Electrical Install 1 LS $ 550,000 $ 550,000 Total Capital Cost $ 3,650,000 Annual Operating Costs Power 1 yr $ 104, $ 104,000 Oxygen 1 yr $ 170, $ 170,000 Manpower 400 hr. $ $ 26,000 Total Annual Operating Costs $ 300,000 Secondary Chlorination - Gas Chlorine Quantity Unit Price per Unit Total Cost Gas Chlorine Feed Equipment (10 MGD, 2 mg/l post filtration, 150 ppd) 1 LS $ 30,000 $ 30,000 Chlorine Gas Scrubber System for Ton Cylinder 1 LS $ 200,000 $ 200,000 Storage and Equipment Building (350 sq. ft.) 1 LS $ 70,000 $ 70,000 Mechanical/Electrical Installation 1 LS $ 115,000 $ 115,000 Total Capital Cost $ 415,000 Annual Operating Costs Gaseous Chlorine 150 lb/day $ 0.25 $ 13,500 Parts/Reagents 1 LS $ 2, $ 2,000 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 41,500 Secondary Chlorination - Sodium Hypochlorite Quantity Unit Price per Unit Total Cost Chemical Feed Pumps, 2 total for post filtration) 1 LS $ 15,000 $ 15,000 Hypochlorite Storage Tanks 2,300 gallons) 2 EA $ 7,500 $ 15,000 Equipment Building (500 sq. ft.) 1 LS $ 100,000 $ 100,000 Mechanical/Electrical Installatoin 1 LS $ 11,250 $ 11,250 Total Capital Cost $ 141,250 Annual Operating Costs Sodium Hypochlorite 12.5% 150 gal/day $ 0.65 $ 35,588 Power (Chemical feed pumps, etc) 1 LS $ 2,500.0 $ 2,500 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 64,088 Secondary Chlorination - On-Site Generation Quantity Unit Price per Unit Total Cost MIOX 150 ppd System 1 LS $ 200,000 $ 200,000 Equipment Building (500 sq. ft.) 1 LS $ 100,000 $ 100,000 Chemical Feed Pumps, 2 total for post filtration) 1 LS $ 15,000 $ 15,000 Mechanical/Electrical Installation 1 LS $ 100,000 $ 100,000 Total Capital Cost $ 415,000 Annual Operating Costs Power (150lb/day x 2KWh) 300 kw-hr. $ 0.10 $ 10,950 Salt (3 lbs/lb chlorine x 150 lb/day) 450 lbs/day $ 0.05 $ 8,213 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 45,163

135 Secondary UV Disinfection/ Primary-Secondary Chlorination Secondary UV Quantity Unit Price per Unit Total Cost ITT/Wedeco K143 Series (1 duty+1 80% UVT for 10 MGD 1 LS $ 690,000 $ 690,000 Equipment Building (1,600 sq. ft.) 1 LS $ 320,000 $ 320,000 Mechnical/Electrical Install 1 LS $ 345,000 $ 345,000 Total Capital Cost $ 1,355,000 Annual Operating Costs Power 1 LS $ 17, $ 17,000 Annual lamp replacement 1 LS $ 7, $ 7,200 Annual Ballast Replacement 1 LS $ $ 350 Cleaning Chemical 1 LS $ $ 300 Manpower 400 hr. $ $ 26,000 Total Annual Operating Costs $ 50,850 Primary/Secondary Chlorination - Gas Chlorine Quantity Unit Price per Unit Total Cost Gas Chlorine Feed Equipment (10 MGD, 1 mg/l pretreatement, 2 mg/l post filtration, 250 ppd) 1 LS $ 40,000 $ 40,000 Chlorine Gas Scrubber System for Ton Cylinder 1 LS $ 200,000 $ 200,000 Storage and Equipment Building (400 sq. ft.) 1 LS $ 80,000 $ 80,000 Mechanical/Electrical Installation 1 LS $ 120,000 $ 120,000 Total Capital Cost $ 440,000 Annual Operating Costs Gaseous Chlorine 250 lb/day $ 0.25 $ 22,500 Parts/Reagents 1 LS $ 3, $ 3,000 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 51,500 Primary/Secondary Chlorination - Sodium Hypochlorite Quantity Unit Price per Unit Total Cost Chemical Feed Pumps, 4 total (2 for pretreatment, 2 for post filtration) 1 LS $ 25,000 $ 25,000 Hypochlorite Storage Tanks 3,750 gallons) 2 EA $ 10,000 $ 20,000 Equipment Building (750 sq. ft.) 1 LS $ 150,000 $ 150,000 Mechanical/Electrical Installatoin 1 LS $ 17,500 $ 17,500 Total Capital Cost $ 212,500 Annual Operating Costs Sodium Hypochlorite 12.5% 250 gal/day $ 0.65 $ 59,313 Power (Chemical feed pumps, etc) 1 LS $ 3,000.0 $ 3,000 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 88,313 Primary/Secondary Chlorination - On-Site Generation Quantity Unit Price per Unit Total Cost MIOX 250 ppd System 1 LS $ 250,000 $ 250,000 Equipment Building (650 sq. ft.) 1 LS $ 130,000 $ 130,000 Chemical Feed Pumps, 4 total (2 for pretreatment, 2 for post filtration) 1 LS $ 25,000 $ 25,000 Mechanical/Electrical Installation 1 LS $ 125,000 $ 125,000 Total Capital Cost $ 530,000 Annual Operating Costs Power (250lb/day x 2KWh) 500 kw-hr. $ 0.10 $ 18,250 Salt (3 lbs/lb chlorine x 250 lb/day) 750 lbs/day $ 0.05 $ 13,688 Manpower (hr/yr) 400 hr. $ $ 26,000 Total Annual Operating Costs $ 57,938

136 Attachment B 20- Year Present Worth Summary

137 20-Year Present Worth for Disinfection Strategies Description of Alternative Capital Cost Annual O&M Present Worth of O&M 20 Year Present Worth 20 Year Present Worth, Total ($) ($/Year) ($) ($) ($) Chlorination Only Alternatives ( MGD) Gas Chlorine $ 562,500 $ 75,500 $ 940,897 $ 1,503,397 $ 1,503,397 Sodium Hypochlorite $ 412,500 $ 149,625 $ 1,864,658 $ 2,277,158 $ 2,277,158 On-Site Generation $ 850,000 $ 89,875 $ 1,120,041 $ 1,970,041 $ 1,970,041 Primary Ozone/Secondary Chlorination ( MGD) $ 3,650,000 $ 300,000 $ 3,738,663 $ 7,388,663 Gas Chlorine $ 415,000 $ 41,500 $ 517,182 $ 932,182 $ 8,320,845 Sodium Hypochlorite $ 141,250 $ 64,088 $ 798,678 $ 939,928 $ 8,328,591 On-Site Generation $ 415,000 $ 45,163 $ 562,831 $ 977,831 $ 8,366,494 Primary Chlorination/Secondary UV ( MGD) $ 1,355,000 $ 50,850 $ 633,703 $ 1,988,703 Gas Chlorine $ 440,000 $ 51,500 $ 641,804 $ 1,081,804 $ 3,070,507 Sodium Hypochlorite $ 212,500 $ 88,313 $ 1,100,575 $ 1,313,075 $ 3,301,779 On-Site Generation $ 530,000 $ 57,938 $ 722,036 $ 1,252,036 $ 3,240,739

138 Appendix C Treatment Residuals and Solids Handling Alternatives

139 NID Regional Water Supply Project Technical Memorandum Treatment Residuals and Solids Handling Alternatives Prepared For: Prepared By: Reviewed By: Nevada Irrigation District and City of Lincoln David Hunt, P.E. Gerry LaBudde, P.E. 1.0 INTRODUCTION This section provides information about the overall NID Regional Water Supply Project as it relates specifically to the background, purpose, and scope of the treatment residuals and solids processing strategy. 1.1 BACKGROUND To address the projected demand for the treated water in the City of Lincoln (the City) and Nevada Irrigation District (the District), the District and the City joined cooperatively and selected to perform a study to evaluate and select a site for a new regional water treatment plant (WTP) facility. The results were presented in the Lincoln Area Water Treatment Plant Planning and Site Study, (ECO:LOGIC, August 2005 [Siting Study]). Subsequent to the Siting Study, ECO:LOGIC was selected to prepare a planning and predesign study for the NID Regional Water Supply Project (Project). This study was commissioned by the District to investigate the feasibility of the Project, and to recommend the location, size, and configuration of Project components. The purpose of the Planning and Predesign Study is to recommend feasible alternatives to the Project as a whole, as well as alternatives for individual Project components, and then incorporate these recommendations into a proposed Project description for use in the Draft Environmental Impact Report (DEIR). 1.2 EVALUATION APPROACH The NID Water Treatment Plant (WTP) is expected to expand in three phases, 10 million gallons per day (MGD), 20 MGD and 40 MGD, utilizing conventional water treatment processes incorporating flocculation, sedimentation, and granular media filtration, as established in the Water Treatment Process Screening Technical Memorandum (TM). All treatment residuals and solids handling processes discussed are sized for the 40 MGD capacity. NVID Appendix C-1 Regional Water Supply Project

140 Solids Handling Alternatives 1.3 WATER SUPPLY The proposed raw water sources include the Combie Ophir Phase 1 and the Camp Far West Canals as the primary water supply, and the Whiskey Diggins Canal as a backup water supply. Coon Creek at Garden Bar Road is another potential raw water turnout. Combie Reservoir is the source of water for the primary water supply. Initially, the water will be conveyed through a combination of existing canals (with appropriate modifications), natural drainage courses currently used to convey District water, and new pipelines. Eventually the raw water pipeline will likely extend from Combie Reservoir to the treatment plant site. The Combie Ophir water quality data was used in this study in order to estimate solids generated at the proposed water treatment plant. 1.4 TREATMENT PROCESS The proposed treatment processes for the NID WTP are traditional coagulation with rapid mixing, flocculation, and sedimentation basins incorporating plate settlers followed by granular media filters. These solids producing treatment processes are used as the basis of design to evaluate the alternatives for the treatment residuals and solids handling processes. 1.5 RECYCLED WATER Each of the treatment and monitoring processes throughout the treatment plant create a process waste stream to carry the process waste to the solids collection and process facilities. These include sludge from the bottom of the plate settlers, backwash (BW) water from the filters, filter to waste water (FTW), decant water from the sludge drying ponds, and the drains from the various monitoring and sampling stations. The solids handling process streams will be clarified to remove suspended solids, the thickened solids will be sent to solids drying facilities, and the clarified process water will be returned to the head of the treatment plant for retreatment. The California Cryptosporidium Action Plan (CAP) requires an operational goal for all clarified solids process stream effluent to try and achieve 2 NTU or less, and the recycled water should be less than ten percent of the raw water flow. The FTW and process monitoring streams will be handled separately from the solids process stream due to their already low turbidity and differing treatment requirements before recycling. 1.6 SOLIDS PRODUCTION Although the plant is expected to expand in phases, with initial construction expected to be at 10 MGD, the site plan and treatment residuals planning study needs to account for the full 40 MGD capacity. Table 1 presents the estimated solids quantities to be produced for the 40 MGD treatment plant capacity based on projected seasonal demand curves. Two coagulants, aluminum sulfate hydrate (Alum) and poly-aluminum chloride (PACl) are being considered for the water treatment process. Currently NID uses alum as the primary coagulant and uses lime to adjust the ph and alkalinity of the water in the existing water treatment plants. Discussions with NID have indicated that they would like to search for an alternative to the lime process for future alkalinity adjustment during the coagulation process. For quantifying the NVID Appendix C-2 Regional Water Supply Project

141 Solids Handling Alternatives amount of solids produced, alum for coagulation and soda ash for alkalinity adjustment were used. Both the alum and soda ash will produce conservative numbers for estimating the quantities of solids that may be produced prior to actual jar testing the source water and selecting the chemicals to be used at the treatment plant. Table 1 Estimated Solids Production (a) Month Estimated Average Monthly Production Combie Ophir Turbidity Alum Dose Polymer Dose Alkalinity Adj. Dose Dry Solids (MGD) (NTU) (mg/l) (mg/l) (mg/l) (PPD) January ,572 February ,412 March ,887 April ,041 May ,381 June ,994 July ,233 August ,206 September ,749 October ,963 November ,770 December ,388 Monthly Avg Average Monthly Dry Solids Production (PPD) 2,466 Average Dry Solids Production (lbs/mg) 95 (a) Based on projected seasonal demand curves The solids were calculated using the following equation: Where: S=8.34 (Q) (0.44 Al + bt+ P+4*) S= Solids production (lb/day) Q= Plant Flow (mgd) Al= Alum dose (mg/l) b= Correlation coefficient between turbidity and suspended solids T= Raw water turbidity (NTU) P= Polymer dose (mg/l) *=15 mg/l Alkalinity adjustment dose is expected to add approximately 4 mg/l to the solids production NVID Appendix C-3 Regional Water Supply Project

142 Solids Handling Alternatives Typical b values range from 0.5 to 2.0 for surface water. A value of 1.2 was used in this evaluation since no correlation data was available for the proposed raw water sources. As shown in Table 1, the estimated average plant solids production is approximately 2,466 pounds per day (PPD) of dry solids, and an estimated peak month (July), maximum day value of 4,233 pounds. The average flow rate is 25.9 MGD, which equates to an average day dry solids production rate of 95 pounds per million gallons (lbs/mg). This analysis is based on the estimated average monthly dry solids production of 2,466 PPD for the passive solids handling systems considered as those systems have a greater holding or averaging capacity. The maximum monthly solids production rate of 4,233 PPD is used for the mechanical dewatering systems considered, as they need to be sized to handle the peak solids production rate, or be combined with solids storage areas to effect an averaging solids flow rate for the system. 2.0 SOLIDS HANDLING PROCESSES The solids dewatering processes are arranged into three general categories dependent on their efficiencies: solids thickening, dewatering, and drying, as shown in Table 2. Typically treatment plants will employ solids thickening followed by dewatering and or a drying process to achieve the solids concentration necessary for disposal. Table 2 Solids Concentration by Dewatering Process Process Solids Concentration Thickening 8% Dewatering 8% to 35% Drying >35% The disposal method and location chosen will be a crucial factor in determining the solids handling method best suitable for the WTP. 2.1 SOLIDS THICKENING Solids thickening is usually one of the primary steps utilized by a WTP to increase the efficiency of a water treatment plant and reduce the size of the dewatering facilities footprint. The recovered water is recycled to the head of treatment process, and the thickened sludge is sent to the dewatering facilities. Thickeners usually receive flows with solids in the 0.5 to 1.0 percent range, and thicken it to about 2 percent prior to the dewatering process, except for specific technologies such as the drying filter bed systems. The most common options utilized include solids thickening with settling lagoons, gravity thickeners (clarifiers), or combination mechanical thickeners/drying beds being seen more recently in some parts of the country. NVID Appendix C-4 Regional Water Supply Project

143 Solids Handling Alternatives UP FLOW CLARIFIERS Gravity thickening up flow clarifiers are commonly used in water treatment plants for thickening solids from the solids handling process. The process is simple and requires little operator attention other than chemical feed and turbidity monitoring. Clarifiers are usually circular concrete basins with solids scraping removal system and v-notch overflow weirs. Effluent solids concentrations from the gravity thickener range from 2 to 4 percent. Up flow clarifiers provide proven technology in a small footprint that will allow for redundancy at build out with low O&M costs PLATE SETTLING CLARIFIERS Plate settling clarifiers are very similar to gravity thickening with up flow clarifiers. The plate settlers are placed at an angle to increase solids settling area. The use of settling plates reduces the footprint compared to a conventional up flow gravity clarifier. A polymer may be required to aid in thickening and settling. When used for sludge thickening, plate settlers require higher maintenance than up flow clarifiers, as the plates will need to be drained and cleaned on an occasional basis to maintain efficiency and to prevent short circuiting. Plate thickeners provide proven technology in a small footprint that will allow for redundancy at build out SLUDGE LAGOONS The selected WTP site topography and hydraulic profile for the WTP does not lend itself to the use of large sludge lagoons for use as solids thickeners, as they would require inordinately expensive amounts of cut and fill and mass grading given the slopes at the site. 2.2 SOLIDS DEWATERING AND DRYING The following section discusses passive and mechanical methods of dewatering WTP sludges. Evaporative dewatering is less energy intensive than mechanical methods, but requires a larger site footprint EVAPORATIVE DEWATERING Dewatering with drying beds is the primary option for evaporative dewatering with alum sludges. The climate data used to analyze the evaporation potential for the site was from Auburn and the Auburn Dam project ( ). The area climate is considered moderate with wet winters and hot summers. The average precipitation is approximately 36 inches per year, and will mainly affect the performance of the drying beds during the winter months. By design, excess water will be decanted from the drying beds, and therefore they will not be excessively affected by precipitation other than the reduction of drying potential during those months. The average monthly evaporation rates are shown in Figure 1. NVID Appendix C-5 Regional Water Supply Project

144 Solids Handling Alternatives Evaporation Precipitation Evaporation, in/mo Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec. Months Figure 1 Average Evaporation - Precipitation Rates near Auburn, CA DRYING BEDS Drying beds or mixed drying beds are typically shallow holding structures with under drains (mixed beds) and decant systems, or they may have paved surfaces with decant systems and rely on occasional mechanical mixing and evaporation for the dewatering process. They are designed to retain solids 1 to 3 feet deep and with proper mixing equipment can dry solids up to 50 percent dry weight. Typical loading rates are approximately 10 to 20 lbs/sf/yr. However, during the months of low evaporation (from November to April) the solids applied will require a longer drying period to reach the 50 percent dry solids range. Since drying beds typically receive sludge with only 2 percent solids, the mixed drying beds are equipped with under drains and decant pump stations to return the supernatant liquid from the retained settled solids back to the solids clarifiers for ultimate return to the head of the treatment process DESKINS DRYING BED FILTER SYSTEMS Deskins drying bed filter systems are very similar to typical drying beds; however, they incorporate a filtration bed to maximize drying potential. Filter plates are usually made of high strength plastics and installed in the drying bed to capture the solids and allow the filtrate to drain through and discharge through an under drain system. This allows for significantly faster drying times and reduces the footprint of the drying beds. A polymer is typically added to aid in the solids concentration process. The beds are typically 1 to 2 feet deep and can achieve dry solids NVID Appendix C-6 Regional Water Supply Project

145 Solids Handling Alternatives contents of 50 percent or better. These systems also eliminate the need for a gravity thickener as they can accept solids directly from the sedimentation basin at 0.5 to 1 percent solids. Alum sludges have not historically performed well with under drain systems without constant operator attention mechanical aeration or mixing to break up the crust. These are operator intensive and require specially made mixing front end loaders so to not break up the plastic under drains. 2.3 MECHANICAL DEWATERING An alternative to using drying beds for dewatering is mechanical dewatering. The various options for mechanical dewatering are discussed in the following sections CENTRIFUGE Dewatering by centrifuge is achieved through the process of applying a centrifugal force through rapid rotation of a cylindrical bowl to separate the solids from the water. The performance of the centrifuge is dependent on the characteristics of the added coagulants and the source water. A polymer is typically added to aid in the dewatering process in the centrifuge. The total solids concentration that a centrifuge will produce can range from 16 to 25 percent. The average solids recovery is generally estimated to be around 95 percent. Centrifuges are most economically operated on a continuous basis; however, they can be operated in shifts. Centrifuges require minimal operator attention when the machines are running properly. However, the cost and downtime can be significant when maintenance is needed to repair a centrifuge. A back-up centrifuge or alternative dewatering process is typical as a backup in the event a centrifuge is down for repairs in order to continue normal plant operations PLATE & FRAME OR BELT FILTER PRESS The plate and frame filter press is used for solids dewatering by pumping the solids into a filter plate where the solids are compressed. A high pressure feed pump forces the solids into chambers where the liquid passes through a cloth medium and out through discharge ports. More and more solids are forced into the chamber building a cake that is removed when the process is complete and the plates are separated. The plate and frame presses typically run in two to three hour cycles. Similar to the centrifuge, a polymer is added to aid in the dewatering process. Filter presses can also utilize a membrane to achieve higher pressures in the filter plate allowing for a higher solids concentration. The membrane filter presses can achieve solids concentrations in the range of 25%. Typically, the membrane filter presses have higher capital and operating costs, but are able to provide a dryer cake in less time than a typical plate and frame press. Filter presses require more operator attention than a centrifuge, and all mechanical dewatering systems are more labor intensive than drying beds. Two filter presses, and a sludge storage area may be required in the event a filter press is down for maintenance. Belt and filter presses are high maintenance and require constant operator attention, and are not recommended for further evaluation. NVID Appendix C-7 Regional Water Supply Project

146 Solids Handling Alternatives 2.4 SOLIDS DRYING AND STORAGE BEDS Incorporation of a separate final solids drying and storage area will be advantageous for the water treatment plant at the 40 MGD capacity. A separate storage area will allow the operators to clean the drying beds at the end of the drying season of all solids in the basins, and give the operators somewhere to store the solids and provide an extra drying area if necessary. This will provide clean dewatering beds ready for a new season, and potentially increase the percent solids for disposal that can be achieved by providing a greater drying area, and higher solids content in the sludge will lower volume and the disposal fees that NID will incur. A separate final drying area will also provide increased flexibility for operational staff if required. It may not become necessary to incorporate this option for further solids drying until the plant reaches the 40 MGD capacity, as there will be excess solids drying potential in the designated drying beds. However, there will be considerable value in having an area designated to store residual solids at the site when it s required. 3.0 SOLIDS DISPOSAL OPTIONS Solids disposal can typically represent a substantial portion of the solids handling operating costs. Water treatment solids are not high in nutrients, unlike biosolids, so are not typically used for land application disposal. The alum salts content may potentially have adverse affects on some plants and water sources. Trucking the solids to a nearby landfill is recommended as the best option for disposing of the dewatered solids. Based on the US EPA 40 Code of Federal Regulations Part 258, the alum cake is required to pass a paint filter liquids test as well as the Toxicity Characteristics Leaching Procedure (TCLP) to be accepted by the landfill. Typically, potable WTP sludges have no problem passing the TCLP analysis, and water treatment solids that have been dewatered in excess of 20 percent dry solids will pass the paint filter test. Landfill disposal is considered the best option for disposing of the treatment plant s dewatered solids, and Table 3 shows a comparison of the disposal costs for the dewatered solids at the two nearest landfill sites. The costs for disposal at the Western Regional Landfill were used for the present worth evaluations. Landfill Table 0 Landfill Hauling and Tipping Costs Round Trip Distance (miles) Minimum Solids Content (%) Tipping Fee (a) ($/ wet ton) Ostrom Rd Sanitary Landfill $33 Western Regional Sanitary (a) Tipping fee does not include hauling fees. NVID Appendix C-8 Regional Water Supply Project

147 Solids Handling Alternatives 4.0 ECONOMIC EVALUATION An economic evaluation was performed on each of the solids handling process presented in section 2.0. The economic evaluations for each alternative included capital costs, labor, power, chemical costs, and solids disposal fees. The capital cost and 20-year present worth for each of the solids handling processes previously discussed are shown in Table 4. These costs represent the costs of the equipment and installation of the major unit processes including gravity thickening, lagoons, drying ponds, filter presses, centrifuges, and drying filter systems for the 40 MGD capacity. The costs presented are based on information provided by equipment vendors and information gathered from actual bid prices from other projects of similar nature. Description of Process 1.0 Thickening Table 4 Solids Process Handling Capital Costs Capital Cost ($M) Annual O&M 20 Year Present Worth ($M) 1.1 Gravity Thickener Clarifier $1.7 $54,208 $ Lagoons $1.3 $103,141 $ Plate Clarifier $1.8 $65,050 $ Solids Dewatering 2.1 Filter Press $2.4 $150,884 $ Centrifuge $2.3 $139,839 $ Dewatering Beds $1.8 $111,722 $ Deskins Filter Beds $2.8 $165,770 $ NON ECONOMIC EVALUATION FACTORS Each of these solids or treatment residuals handling facilities presented have a particular non economic component associated with it that also needs to be complimentary to the treatment plant, the NID staff, and acceptable to other interested parties that may have a concern in the appearance or operation of the treatment plant. Discussions with operations staff have indicated have indicated a preference for traditional solar dewatering beds with under drain systems, and a prejudice against the mechanical dewatering mechanisms such as the filter belt presses as being too labor intensive. The alternatives producing the highest percent solids will also produce the least amount of traffic to remove the solids from the treatment plant. A drying/dewatering system that produces 20 percent solids will produce increased vehicle and incur increased disposal costs over a drying NVID Appendix C-9 Regional Water Supply Project

148 Solids Handling Alternatives method that produces 50 percent solids. The preferred alternative needs to provide operational flexibility, redundancy, ease of operation, and acceptable visual impacts on the surrounding neighborhood as well. 6.0 SUMMARY AND RECOMMENDATIONS Based on the evaluation of the technologies available to best suit the site hydraulics and topography, and based on input received during meetings with NID staff, solids thickening clarifiers with mixed dewatering and drying beds is the recommended alternative for the NID Regional Water Supply Project. It is also recommended that the District incorporate a designated alternate solids drying/storage area at the site for flexibility at build out. This configuration has a compact footprint, fits well on the site, minimizes the amount of required site work, and has a low present worth value. A schematic diagram of the recommended alternative is shown in Figure 2. The recommended alternative s combined solids thickening and dewatering treatment costs are shown in Table 5. The complete cost analysis for the recommended alternative is included in Attachment A. Table 5 Solids Thickening and Dewatering Capital and O&M Costs Preferred Alternative Gravity Clarifier with Mixed Dewatering/Drying Beds Capital Cost ($M) Annual O&M 20 Year Present Worth ($M) $3.5 $168,240 $5.76 The NID Water Treatment Facility is expected to expand in three phases, 10 MGD, 20 MGD, and 40 MGD. However, the solids handling facilities, including the solids clarifier, the FTW equalization basin clarifier that should be operated sequentially with the solids clarifier and the dewatering beds should be initially sized and installed for 40 MGD. This will reduce the need for multiple clarifier and drying bed installations, reduce the overall cost of construction, reduce the size of the WTP footprint, and increase the operational flexibility and plant redundancy until plant build out occurs. NVID Appendix C-10 Regional Water Supply Project

149

150 Attachment A Cost Analysis for Recommended Alternative

151 Gravity Thickener with Drying Beds Summarized Project Cost Total Cost 1.0 Thickening 1.1 Gravity Thickener Clarifiers $ 1,800, Recycle Pump Station $ 359, Sludge Transfer Pump Station $ 125, Polymer storage and feed system $ 30, Electrical $ 72, Drying Beds Dewatering 2.1 Excavation/Grading $ 250, Polymer storage and feed system $ 30, Loader $ 75, Concrete Lining $ 1,657,333 Total Capital Cost $ 5,937, Annual Operating Costs 3.1 Power $ 30, Polymer $ 7, Manpower $ 94, Landfill disposal $ 36,010 Total Annual Operating Costs $ 168,240

152 Appendix D Preliminary Chemical Treatment Process Selection

153 NID Regional Water Supply Project Technical Memorandum Preliminary Chemical Treatment Process Selection Prepared For: Prepared By: Reviewed By: Nevada Irrigation District and City of Lincoln Dave Hunt, P.E. Gerry LaBudde, P.E. 1.0 INTRODUCTION The purpose of this report is to present the unit processes for the NID surface water treatment plant (WTP) and discuss and recommended chemical additives, estimated doses, and storage facility footprints for design purposes. Chemical recommendations are based on the results of desktop analyses and typical dose data from other facilities with similar raw water characteristics. 2.0 NID WATER TREATMENT UNIT PROCESSES AND RECOMMENDED CHEMICAL TREATMENT 2.1 PRE-OXIDATION/PRETREATMENT Pre-oxidation/pretreatment is the addition of an oxidant to the raw water at the entrance to the treatment plant. This process is used to disinfect, reduce tastes and odors, inhibit algae growth and improve coagulation and filter performance. Typical oxidants include chlorine, chlorine dioxide and ozone. The pre-oxidation/pretreatment chemical dose will depend on source water quality characteristics and intent of the treatment. Less oxidant is required to improve treatment than to disinfect. Chlorine is the recommended oxidant for NID with the intent of improving the coagulation performance. The estimated chlorine dose for pre-oxidation/pretreatment is 1.0 mg/l, injected at the headworks. These conclusions are discussed further in the Disinfection Strategies discussion (Appendix B of the BDR). 2.2 COAGULATION/FLOCCULATION UNIT PROCESS/ENHANCED COAGULATION Coagulation and Flocculation Coagulation and flocculation are essential for the removal of suspended solids from surface water. While large solids will naturally settle out, chemical coagulants target the difficult-toremove colloidal particles (0.01 to 5 µm) within the water. Coagulants function by neutralizing the negative charge of colloidal particles, resulting in colloidal destabilization and particle NVID Appendix D-1 Regional Water Supply Project

154 Preliminary Chemical Treatment Process Selection aggregation and flocculation. It is important that coagulants are introduced at the point of greatest mixing intensity within the rapid mixing process to maximize particle destabilization at the lowest dose. The coagulation reaction occurs rapidly, typically in the first few seconds after the addition of coagulant during the rapid mix process. Following coagulation, flocculation consists of the aggregation of particles to form floc that can be removed in the sedimentation and filtration processes. To accomplish flocculation, sufficient mixing energy needs to be applied to create particle collisions and develop floc masses. Three or four flocculation stages, of decreasing mixing energy are desirable for floc formation. Plug flow is very important for the development of floc with uniform size and settling characteristics Enhanced Coagulation NID source water TOC levels are close to the 2 mg/l Safe Drinking Water Act limit, triggering TOC removal requirements per the disinfection by-product rule (DBR). If the annual average TOC levels exceed the limits during plant operation, the EPA would likely require NID to remove the TOC using enhanced coagulation. Under the DBR, enhanced coagulation is defined as the addition of excess coagulant for the removal of DBR precursors by conventional filtration systems. It may also be necessary to reduce the coagulation ph to a range between 5.5 and 6.5. Presented in Table 2 are the TOC removal requirements based on the source water TOC concentration. Sources of TOC include naturally occurring organic matter (NOM) that results from the natural decay of organic material such as grasses, roots and wood. TOC in surface waters appear as soluble or colloidal dispersions of semisoluble matter. Enhanced coagulation may be achieved by a single coagulant, but is usually more successful with coagulant and polymer blends. Table 2 TOC Removal Requirements by Enhanced Coagulation for Plants Using Conventional Treatment Source Water TOC Source water alkalinity (mg/l as CaCO3) (mg/l) 0 to 60 >60 to 120 >120 > % 25.0% 15.0% > % 35.0% 25.0% > % 40.0% 30.0% Source: USEPA (1999) NVID Appendix D-2 Regional Water Supply Project

155 Preliminary Chemical Treatment Process Selection Coagulants Typical coagulants include aluminum sulfate (alum), polyaluminum chlorides (PACl), ferric chloride, and ferric sulfate. These typical coagulants, including their pros and cons, are listed in Table 3. Alum is the most widely used coagulant in water treatment in the United States. Table 3 Comparison of Common Coagulants for Water Treatment Chemical Coagulant Advantages Disadvantages Alum (aluminum sulfate) Polyaluminum Chloride (PACl) Ferric chloride and ferric sulfate Low cost Less acidic than the ferric coagulants Less chemical required than alum or ferric Produce less sludge Has less of an impact on ph and alkalinity Residuals are easier to dewater Wide effective dosage range Good removal of organics Low cost More acidic than PaCls Lower Total Organic Carbon removal than ferric coagulants Residuals are difficult to dewater Costly compared to other coagulants Iron residuals High iron residuals can plug filters and stain Acidic Residuals can be very difficult to dewater Coagulant Selection Factors influencing coagulant selection are temperature, the nature of suspended solids and other raw water quality characteristics, treatment performance, cost, operator familiarity/preference, delivery reliability and chemical storage considerations. The inorganic coagulants considered for use at NID include alum and PACl. Iron based inorganic coagulants were not considered for NID due to disadvantages associated with iron residuals (staining) and sludge dewatering. The expected alum dose range for the source water considered is from 10 to 30 mg/l. The expected PACl dose range is from 5 to 20 mg/l. Enhanced coagulation doses are expected to be close to the high end of these dose ranges. Alum was selected over PACL for purposes of sizing the chemical building, as it has the greatest estimated dose and will result in the largest storage and building footprints. Based on data gathered at the Metropolitan Water District of Southern California s 5.5 MGD demonstration plant in 1992 treating Colorado River water with similar TOC levels as NID WTP water, a typical enhanced coagulation dose of 20 mg/l of alum will be used for the purpose of storage/ NVID Appendix D-3 Regional Water Supply Project

156 Preliminary Chemical Treatment Process Selection building sizing. This dose would only be used during the winter months when the TOC levels are historically over the 2 mg/l limit. If a different coagulant or dose is chosen, the sizing of the chemical and dewatering facilities will need to be revised. Optimal coagulant doses for enhanced coagulation must be determined by jar or pilot testing and are beyond the capability of a desktop analysis Coagulation Performance Monitoring A variety of monitoring techniques are used for monitoring the coagulation process. Common techniques and measurements used are jar testing, streaming current instruments, zeta potential, visual observations, UV absorbance, ph and alkalinity. Most utilities use a combination of these techniques to monitor performance. 2.3 SEDIMENTATION/CLARIFICATION UNIT PROCESS The majority of settleable particles formed during the coagulation and flocculation processes will be removed during the sedimentation process thus reducing the particle load on the filters. Sedimentation serves to reduce the potential of cysts passing through the treatment process. The sedimentation capacity is determined by selecting a surface overflow rate (gpm/ft 2 ) that will effectively remove particles in the basin. Important factors affecting the design of the sedimentation process include the nature of the raw water suspended solids, water temperature, plant flow rate and particle settling velocities. It is important to note that basin inlet and outlets should be designed not to disrupt settling conditions or cause short circuiting or floc shear. Sludge removal equipment should be designed to facilitate settled solids removal on a regular basis and not allow sludge build-up. Chemicals that affect the sedimentation process include coagulants and flocculants previously discussed in the coagulation/flocculation section. 2.4 FILTRATION PROCESS The filtration process is considered the most vital component of the treatment process relative to the removal of particulate matter, including microbial contaminants, making a continuous high level filter performance essential. Filter aid chemicals are typically used to maximize particle removal in the filter process. These chemicals are polymers added to the sedimentation effluent. If a filter aid is used, chlorinated backwash water ( 1 mg/l free chlorine) can be used to assist in the removal or prevention of polymer accumulation. Coagulants or polymers added to the backwash water or influent settled water have been used to minimize filter ripening time (time needed to attain normal, low turbidity water following a backwash). NVID Appendix D-4 Regional Water Supply Project

157 Preliminary Chemical Treatment Process Selection Monitoring Filter Performance Both turbidimeters and particle counters are typically used to monitor filter performance and assess when to initiate a backwash process or when to return a filter to service following filter ripening. 2.5 DISINFECTION PROCESS The disinfection process is the final pathogenic barrier of the WTP and functions to inactivate any pathogens that pass through the other treatment processes. Disinfection processes at NID WTP were selected to achieve compliance with California and USEPA regulations. Chlorination with sodium hypochlorite is planned for preoxidation, primary/secondary disinfection and to achieve a chlorine residual in the distribution system. Chlorination is planned at the following locations (chlorine dosages are assumed maximums and are used for facility sizing): Preoxidation (headworks) : 0.5 mg/l, maximum Pretreatment: 0.5 mg/l, maximum Post Filtration: 1.5 mg/l, maximum (minimum free residual of 0.2 mg/l in distribution system) Backwash Water (1.0 mg/l) The maximum expected process water chlorine dose is 2.5 mg/l, which corresponds to a daily chlorine consumption of approximately 1000 gallons at a build out plant capacity of 40 MGD. Chlorinated backwash water ( 1 mg/l free chlorine) can be used to assist in the removal or prevention of polymer accumulation or mudball formation. The hypochlorite storage tanks and chemical feed equipment will be contained in the chemical building. Four polyethylene storage tanks containing a 30 day supply of hypochlorite (29,000 gallons) are planned. Four pairs of chemical metering pumps (duty and standby pumps) are planned to supply chemical to each of the above listed feed locations. 2.6 CORROSION CONTROL Internal corrosion of a water distribution system leads to failure of pipes (leaks or reduced carrying capacity) or unwanted changes in water quality (increased copper and lead concentrations). Increasing the ph is an effective and common practice to reduce the concentration of lead and copper in tap water. The Langlier and Calcium Carbonate Precipitation Potential (CCPP) values for NID source water indicate undersaturation with respect to calcium carbonate with saturation achieved at a ph of 9.1. For predesign purposes, increasing the ph to 8.0, for control of copper and lead corrosion, is recommended. This increased ph will also prevent the precipitation of CaCO 3 within the distribution system. NVID Appendix D-5 Regional Water Supply Project

158 Preliminary Chemical Treatment Process Selection 2.7 POLYMERS USED TO AID PROCESSES Polymers can be used to increase the effectiveness of coagulation and flocculation by increasing floc strength and settleability. Polymers also are used to increase filterability and reduce sludge volume and overall operating costs. In cases where utilities use a polymer as a primary coagulant, significantly less sludge is produced as compared to alum. Polymers available to the water industry are numerous (1000+) and generally proprietary. Polymers are manufactured as both powders and liquids, and their uses include primary coagulants, coagulant aids, flocculant aids, filter aids, backwash water conditioning and solids thickening/dewatering aids. Coagulant aids are added to the rapid mixer, flocculant aids are added immediately following the rapid mixer, filter aids are added to the sedimentation effluent and conditioning aids are added prior to dewatering processes. Polymers consist of long chain molecules made up of repeating monomer units that are linked together in linear or branched configuration with functional groups attached periodically along the chain. The functional groups may be negatively charged (anionic polymers), positively charged (cationic polymers) or possess an overall neutral charge (nonionic polymers). The length of the polymer chain is indicated by its molecular weight. In general, cationic low molecular weight polymers are used as coagulants, and high or very high molecular weight polymers (regardless of charge) are used as flocculants, filter aids and conditioning aids. Since polymers are proprietary, making an accurate estimation for dosing is improbable. Selection processes can be conducted using jar tests, pilot scale tests and full scale tests. Some considerations when using polymers are as follows: Special polymer feed equipment are required. Some challenges associated with polymers include extreme phs (high or low), high viscosity and limited solubility (requiring mixing and sometimes requiring hot water mixing). Chlorine residuals may degrade some polymers. Dilution water free of chlorine would be required for these polymers. Highly viscous polymers are extremely slippery and can be hazardous if spilled. Polymers are vulnerable to aging. Inconsistency between manufactured batches may require QA/QC checks, requiring lab analyses (jar testing or viscosity determinations) with each delivery. Overdosing is possible (i.e. mudballs, poor performance, scum formation) NVID Appendix D-6 Regional Water Supply Project

159 Preliminary Chemical Treatment Process Selection Polymers and their associated facilities are planned for the NID WTP. The polymer types and their probable dose ranges are shown in Table 4. Table 4 Comparison of Common Polymers and Doses for Water Treatment Polymer Probable Polymer Dose Range (mg/l) Coagulant aid (Typically Cationic) Flocculent aid (Typically Anionic) Filter aid (Typically Nonionic) Solids Thickening Cationic or Anionic The scope of this predesign effort only includes planning for polymer addition and estimating the storage footprint. Ultimately, the polymer selection process will include jar testing, pilot scale testing and full scale testing. 2.8 PH ADJUSTMENT The ability to adjust ph prior to coagulation is important as both ph and alkalinity are critical factors in the coagulation process. For effective coagulation, a ph range of should be maintained. For enhanced coagulation, a ph range of is appropriate. Coagulants such as alum or ferric chloride will consume alkalinity and, in cases of low alkalinity raw water (such as NID), both ph and alkalinity may need to be increased following coagulant addition. In addition to coagulation, ph affects disinfection and corrosion of copper and lead. For optimum disinfection a ph range of is desired. Raw water ph may fluctuate dramatically by season or even diurnally due to temperature and biological factors, requiring ph adjustment to maintain the appropriate ph treatment range. Chemicals typically used to raise ph and add alkalinity, include lime, caustic soda or soda ash. Common chemicals used to depress ph are sulfuric acid or carbon dioxide. Unlike sulfuric acid, carbon dioxide addition will reduce ph without affecting alkalinity. Operator safety and system corrosion are critical factors in selecting, storing and handling the various acids and bases. Presented in Table 5 and 6 are a list of ph adjustment chemicals and noteworthy advantages and disadvantages. Chemicals and associated facilities for both increasing and decreasing ph are planned for the NID WTP. NVID Appendix D-7 Regional Water Supply Project

160 Preliminary Chemical Treatment Process Selection Table 5 Comparison of Common Acids for Water Treatment ph Adjustment Chemical Advantages Disadvantages Carbon Dioxide (CO 2 ) Sulfuric Acid (H 2 SO 4 ) Easy delivery and handling Safe to handle and store Environmentally safe Very difficult to overdose Does not add TDS Already in solution Need carrier water supply and mixing pumps Highly corrosive Adds TDS Table 6 Comparison of Common Bases for Water Treatment ph Adjustment Chemical Advantages Disadvantages Lime (Ca(OH) 2 ) Caustic Soda (NaOH) Soda Ash (Na 2 CO 3 ) Not corrosive and familiar to NID operators Adds alkalinity consumed by coagulant Non corrosive Available in solution Not corrosive or hazardous Adds alkalinity consumed by coagulant Non corrosive May cause severe irritation or burns with chemical contact Mixing unit needed to inject chemical as solution Needs to be slaked Cannot be exposed to outside air Corrosive and hazardous upon chemical contact Severe eye irritant Mixing unit needed to inject chemical as solution Cannot be exposed to moisture from outside air Recommendation Carbon dioxide is recommended to reduce ph due to its general acceptance in water treatment, ease of maintenance, outdoor storage, safety and effectiveness. Soda ash is recommended for ph and alkalinity addition based on its general acceptance, safety, footprint (worst case), and widespread use in water treatment. NVID Appendix D-8 Regional Water Supply Project

161 Preliminary Chemical Treatment Process Selection 2.9 PROCESS SUMMARY FOR NID WTP A summary of the preliminary NID WTP unit processes and chemical additives are shown in Table 7. A preliminary process flow diagram for the NID WTP is shown in Figure 1. Table 7 Summary of the Treatment Processes and Chemical Additives Process Preliminary Chemical(s) Chemical Reaction Location Notes Pre-oxidation/ Pretreatment Sodium Hypochlorite Pre-Floc/Sed., Pre/Post-Filtration, Distribution Natural Organic Matter (NOM) reacts with chlorine to form disinfection by-products. ph Adjustment Carbon Dioxide Soda Ash Pre-Floc/Sed. Ability to lower ph to maintain optimal ph treatment ranges. Coagulation Alum and Coagulant Aid (Cationic Polymer) Pre-Floc/Sed. Increased alum dose need for TOC reduction. Flocculation Flocculant Aid (Anionic Polymer) Pre-Floc/Sed. Jar testing needed to determine mixing energy and floc. aid dose. Filtration Filter Aid (Non-Ionic Polymer) Pre-Filtration Jar testing needed to determine accurate filter aid dose. UV Disinfection None Post-Filtration No chemical addition required. Chlorine Residual Sodium Hypochlorite Prior to Treated Water Storage Disinfection requirement. ph Adjustment (Increase) Soda Ash Prior to Treated Water Storage Ability to raise ph to maintain optimal treatment ph ranges. Corrosion control (copper and lead). NVID Appendix D-9 Regional Water Supply Project

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