Genesee Advanced Water Treatment Facility

Transcription

1 Genesee Advanced Water Treatment Facility Preliminary Engineering Report November 3, 2014 Hatch Mott MacDonald 143 Union Blvd., Suite 1000 Lakewood, Colorado

2 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District TABLE OF CONTENTS CHAPTER 1 INTRODUCTION PROJECT BACKGROUND AND DESCRIPTION NEED FOR PROJECT PROJECT LOCATION... 2 CHAPTER 2 DESCRIPTION OF WATER SYSTEM PLANNING AREA DESCRIPTION EXISTING WATER SUPPLY AND TREATMENT SYSTEM Raw Water Supply Sources Water Treatment Facilities Distribution System WATER SYSTEM LOSSES AND UNACCOUNTED WATER VULNERABILITY ASSESSMENT... 6 CHAPTER 3 WATER DEMANDS AND PLANT CAPACITY WATER SYSTEM DEMANDS WATER TREATMENT PLANT CAPACITY... 7 CHAPTER 4 RAW WATER QUALITY RAW WATER SOURCE AND CONSIDERATIONS ANTICIPATED RAW WATER QUALITY... 9 CHAPTER 5 PROJECT GOALS AND ALTERNATIVES EVALUATION OVERALL PROJECT GOALS ALTERNATIVE TREATMENT PROCESSES AND PROCESS SELECTION ALTERNATIVE SITE LOCATIONS AND SITE SELECTION CHAPTER 6 WATER TREATMENT PROCESS DESIGN WATER TREATMENT PLANT CAPACITY AND PROCESSES TREATMENT GOALS AND PLANT PERFORMANCE WATER TREATMENT PROCESS FLOW DIAGRAM AND DESIGN CRITERIA TREATMENT FACILITY FLOOR PLAN HYDRAULIC PROFILE WATER TREATMENT PROCESS AND SYSTEMS DESIGN Raw Water Supply and Coagulation Flocculation and Sedimentation Membrane Treatment System Granular Activated Carbon Finished Water Storage and Disinfection Finished Water Pumping Chemical Feed Systems Waste Tanks Plant Water System i November 2014

3 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 6.7 RESIDUALS MANAGEMENT Summary of Waste Streams and Disposal Analysis of Impacts to WWTP LEVEL OF AUTOMATION WATER TREATMENT FACILITY SECURITY UTILITY SYSTEM CONNECTIONS ENERGY EFFICIENCY CHAPTER 7 RELIABILITY AND REDUNDANCY GENERAL CONSIDERATIONS OVERALL SYSTEM RELIABILITY AND REDUNDANCY... Error! Bookmark not defined Water Distribution System Treatment Processes and Systems Electrical Power Supply PROTECTION FROM FLOODING... Error! Bookmark not defined. CHAPTER 8 SITE LAYOUT AND DESIGN TREATMENT PLANT SITE SELECTION SITE LAYOUT AND IMPROVEMENTS SITE CIVIL DESIGN CRITERIA Site Access, Roadway System and Parking Site Lighting Utilities Site Drainage and Grading Fencing CHAPTER 9 ARCHITECTURAL DESIGN SUMMARY OF BUILDING AREAS Process Areas Administrative Areas BUILDING LAYOUT AND APPEARANCE MATERIALS SELECTION Recommended Wall Materials Recommended Roof Materials BUILDING CODE AND REGULATIONS Planning and Zoning Architectural Review Committee Building Permits Fire Protection District Plan Review BUILDING CODE DESIGN CONSIDERATIONS Chemical Storage and Use Building Construction Type and Allowable Area Exiting Fire Suppression and Alarm Systems Plumbing Fixture Counts ADA Accessibility Energy Efficiency ii November 2014

4 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 10 STRUCTURAL DESIGN INTRODUCTION STRUCTURE CHAPTER 11 BUILDING MECHANICAL DESIGN INTRODUCTION HVAC SYSTEMS PLUMBING SYSTEMS FIRE PROTECTION SYSTEM CHAPTER 12 ELECTRICAL SYSTEM DESIGN INTRODUCTION AND OVERVIEW POWER SUPPLY AND GEAR Raw Water Intake Station and Base Pump Station for Raw Water Supply Advanced Water Treatment Facility Backup and Emergency Power CHAPTER 13 PLC/SCADA SYSTEM AND CONFIGURATION INTRODUCTION SYSTEM CONFIGURATION Existing Systems Proposed System CHAPTER 14 OPINION OF PROBABLE COST OPINION OF PROBABLE PROJECT COST Clarifications on Approach, Assumptions and Excluded Items Level of Cost Estimate CHAPTER 15 PROJECT SCHEDULE AND IMPLEMENTATION PROJECT SCHEDULE PROJECT IMPLEMENTATION APPENDICES Appendix A Water System Facility Plan Appendix B Water Monitoring Records for Water Draws / Water Returns Appendix C EPA Certification for Vulnerability Assessment and Emergency Response Plan Appendix D Site Selection Memo Appendix E ACEC Cost Information for Opinion of Probable Project Cost iii November 2014

5 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District LIST OF TABLES Table 3-1: Genesee Historical Water Demands... 7 Table 4-1: Summary of Water Quality Table 6-1: Summary of Treatment System Considerations for the Genesee Advanced WTF Table 6-2: Waste Handling Tanks Table 6-3: Liquid and Mixed Liquid-Solids Waste Stream Descriptions Table 7-1: JWPP Reliability and Redundancy for Major Treatment Processes Table 9-1: Summary of Expected Administrative Area Rooms Table 9-2: Summary of Wall Material Recommendations Table 9-3: Summary of Roofing Material Recommendations Table 9-4: Chemical Classification and Storage Table 12-1: Preliminary Specifications of Main Switchgear iv November 2014

6 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District LIST OF FIGURES Following Page Figure 1-1: Genesee Project Location Map...2 Figure 2-1: District Service Area...3 Figure 2-2: Schematic of Genesee Potable Water System...3 Figure 2-3: Existing Water Treatment Plant Process Schematic...4 Figure 2-4: Existing Water Treatment Plant Site...4 Figure 5-1: Relative Locations of the Water and Wastewater Plants...12 Figure 6-1: Treatment Process- Membrane Filtration with GAC Post Treatment...13 Figure 6-2: Process Flow Diagram...14 Figure 6-3: Design Criteria Summary...14 Figure 6-4: Plant Floor Plan...14 Figure 6-5: Hydraulic Profile...14 Figure 6-6: Modifications for Raw Water Supply...15 Figure 6-7: Finished Water Pumping / System Curves...19 Figure 6-8: Facility Water System Schematic...21 Figure 8-1: Site Layout and Improvements...35 Figure 8-2: Site Utilities...36 Figure 9-1: Water Treatment Floor Plan and Wall Types...39 Figure 9-2: Architectural Rendering...39 Figure 9-3: Architectural Wall Material Options Figure 9-4: Architectural Wall Material Options Figure 9-5: Architectural Roof Material Options Figure 9-6: Architectural Roof Material Options Figure 12-1: Base Pump Station Future One-Line Diagram...54 Figure 12-2: Water Treatment Plant One-Line Diagram...54 Figure 12-3: MCC Load Calculations...54 Figure 15-1: Project Implementation Schedule...59 v November 2014

7 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 1 INTRODUCTION 1.1 PROJECT BACKGROUND AND DESCRIPTION The Genesee W&S District (Genesee or District) operates a package conventional water treatment plant which is approximately 32 years old. Genesee initiated a Water System Facilities Plan in October of 2013 to determine the direction of the District s water treatment systems and associated Capital Investment Plan (CIP). The purpose of the project was to evaluate the existing system and develop an overall plan for a new water treatment plant (WTP). The planning included the following major elements: The Genesee Water Treatment Plant Site Determine whether the existing facility is capable of meeting current and future regulations Identify recommended replacement or upgrade facilities for the existing plant and recommended construction schedule for a new facility Evaluate and document recommended treatment processes, including the pretreatment processes, filtration system, taste and odor treatment considerations, disinfection and chemical feed systems Evaluate facilities residuals handling and management Perform a rapid condition based assessment for the existing WTP building and structures to determine their expected life expectancy and capital investment needs over a 20 year period Identify alternative sites and develop preliminary layout configurations of a new or modified treatment facility, and perform a preliminary siting study Identify facility upgrades and develop a Capital Investment Plan for both the existing and/or new plant sites, so that capital investments for facilities can be planned Develop Opinions of Probable Cost for both Capital and O&M costs The approach to completing the Facilities Plan was to conduct a series of workshops involving a Work Group consisting of two members of the Genesee Board of Directors, two members of Genesee management staff, and two members of the engineering firm Hatch Mott MacDonald (HMM). The Work Group reported to the full Genesee Board during the development of the project. The Water System Facilities Plan recommended that Genesee construct a new advanced water treatment facility that provides more rigorous treatment than the District s current plant. Major treatment processes would include coagulation and flocculation for pretreatment, membrane filtration, granular activated carbon (GAC) and disinfection. In addition, the Facilities Plan 1 November 2014

8 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District recommended that the new plant be constructed at the site of the District s wastewater treatment plant (WWTP) and Administration Building. A copy of the Water System Facilities Plan is included in Appendix A. 1.2 NEED FOR PROJECT Genesee s plant was originally designed to meet a less stringent filter performance requirement than the current standard. It has several physical limitations including somewhat shallow media depth of approximately 38-inches as compared to modern standards, and an antiquated filter under drain system. The plant has a hydraulic flocculation system which is not as effective as current standard designs which use mechanical systems. While finished water turbidities have historically met all drinking water standards and generally indicate good filter performance, recent particle count data has indicated that the filters pass more particulate matter than is considered desirable. The District s operators have noted that the plant can be difficult to operate at times, that the plant has issues with achieving filter runs of more than eight hours, and that backwash waste volumes are high. In addition, removal of the regulated amounts of total organic carbon (TOC) in the raw water is difficult. Most package water treatment facilities are expected to have a useful life of approximately 30 years before the condition of tanks and equipment makes the replacement of the treatment facility more feasible and a better investment than upgrading the existing facility. Additionally, the expectation of more stringent future drinking water quality standards and the likelihood of lower quality raw water from the District s reservoir in the future were factors in deciding that a new treatment facility should be constructed. 1.3 PROJECT LOCATION The new Advanced WTF will be located on property already owned by Genesee, located along Bitterroot Lane on the south side of the District. The Genesee Wastewater Treatment Plant (WWTP) and Administration Building are located on the same site. Figure 1-1 shows the overall site plan with the three facilities. The Genesee Water Treatment Plant Site 2 November 2014

9 NTS EX TENNIS COURTS GENESEE ADVANCED WATER TREATMENT FACILITY BITTERROOT LANE DAISY LANE EX ADMIN BLDG EX LAGOON AUGMENTATION/ STORAGE/ FIRE POND EX WWTP BLDG EX WWTP BLDG FIGURE 1-1 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN GENESEE PROJECT LOCATION

10 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 2.1 PLANNING AREA DESCRIPTION CHAPTER 2 DESCRIPTION OF WATER SYSTEM Genesee is located in the foothills west of Denver, and southwest of Golden. Primary water uses include residential and commercial water use, as well as landscape irrigation. The Genesee water system serves a residential population of approximately 3,700 customers and approximately 30 commercial users. The Genesee service area stretches slightly north of the Interstate Highway 70 to Bear Creek on the south, and contains approximately 2,870 acres. Figure 2-1 shows the Genesee service area. Genesee s current service obligation is at over 98% build-out based on lot development. Using the Genesee Service Plan as a guide, 4,500 people are the expected maximum population served by the District. According to the Service Plan, Genesee is allowed to serve 1,542 residential units, 173 commercial units, and 33 other allocations. Actual development has varied somewhat from the original plan. As a result of Genesee s fast approach to buildout, water demands are not anticipated to increase in the future. The Genesee service area is at 98% of buildout 2.2 EXISTING WATER SUPPLY AND TREATMENT SYSTEM Genesee s existing potable water supply system includes raw water conveyance and storage, treatment, and finished water transmission and distribution facilities. A schematic of the Genesee water system is shown in Figure Raw Water Supply Sources The raw water supply source for Genesee consists of Bear Creek with a reservoir used to store water from Bear Creek. A water intake and pumping structure is located along Bear Creek and is used to pump water to the District s water treatment plant or to the District s 101 acre-foot reservoir that was constructed and placed in service approximately six years ago. Water can be supplied to the District s water treatment plant either from Bear Creek directly or from the reservoir. According to the District operators, the reservoir has served as the primary source of raw water supply since the time it was placed in service Water Treatment Facilities Inlet and Raw Water Pumping facilities located along Bear Creek The Genesee water treatment facility is located along Highway 74 in the vicinity of Lair O the Bear open space, a few miles west of Idledale. The plant is a conventional water treatment 3 November 2014

11 15 MILES TO DOWNTOWN DENVER EXISTING WWTP (NEW WWTP) SITE EXISTING WTP SCALE: 1"=4,000' FIGURE 2-1 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN DISTRICT SERVICE AREA

12 FIGURE 2-2 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN SCHEMATIC OF GENESEE POTABLE WATER SYSTEM

13 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District facility that uses chemical addition, coagulation and flocculation, sedimentation, and filtration followed by chlorine disinfection. Figure 2-3 shows a schematic of the water treatment facilities, and Figure 2-4 shows the overall site. The water treatment processes consisting of the flocculation chambers, sedimentation basins and filters is a combined package system that was constructed during the early 1980s and is over 30 years in age. The treatment processes are discussed in further detail below. Coagulation and Flocculation. Most colloidal material in water (suspended solids that are small enough to pass through a conventional sand filter) has a negative surface electrochemical charge which prevents agglomeration of the particles and thus makes their removal from water difficult. Most pathogenic materials in water demonstrate similar negative surface charges. These materials are removed from water by adding a coagulant such as alum that acts to destabilize the negative surface charge of the particle thereby causing the colloidal material to become charge neutral. This allows the colloidal and pathogenic materials to agglomerate into larger particles. The water containing the charge neutral particles is then passed through a flocculation process which consists of multiple stages of gentle stirring causing these particles to collide and form larger solids. These solids become large enough to either be settled or filtered out of the water. Sedimentation. Sedimentation is used to remove a large percentage of the solids from the water, thereby improving subsequent filter performance and extending the filter run time before backwashing. The water treatment plant uses tube settlers to enhance the natural settling process. The removed solids are washed from the sedimentation basin and discharged to the backwash pond. Filtration. Filtration provides a positive barrier for pathogenic organisms and other suspended solids remaining in the water following settling. Flocculated particles that do not settle out in the sedimentation process are strained out of the water in the filter. The filters have a media depth of approximately 38-inches (not including the underlying support layers), including a 26-inch thick layer of anthracite, and a 12-inch thick layer of sand. The 38 inches of media depth is within a typical range of filter media depths, but may be considered slightly shallow based on current requirements for performance. Disinfection and Finished Water Pumping. Following filtration water flows into the clearwell tank. The clearwell volume provides contact time for disinfection of the water. Gaseous chlorine is fed to disinfect the water and maintain a residual chlorine concentration in the distribution system in order to provide protection from pathogenic organisms. Following disinfection in the clearwell, water is pumped by a high-pressure pump station into the distribution system. Another important aspect of the facility is solids management. Solid materials from the sedimentation basin and backwash waste from the filters are discharged to the Package Filter Unit The Backwash Pond at the Genesee Water Treatment Plant site presents challenges for residuals management 4 November 2014

14 FIGURE 2-3 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN GENESEE WATER TREATMENT PLANT PROCESS SCHEMATIC

15 RAW WATER RESERVOIR PROPANE GAS WTP BUILDING HILLSIDE COLD SPRINGS GULCH ROAD BASE PUMP STATION BACKWASH POND B E A R C R E E K R D ( HWY 7 4 ) GENESEE WATER TREATMENT PLANT FIGURE 2-4 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN WATER TREATMENT PLANT SITE SCALE: 1"=200'

16 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Backwash Pond, which is an open earthen basin. According to District operators, this Backwash Pond was intended to be a temporary facility at the time of construction but ultimately became the permanent structure. The Backwash Pond is not segmented and therefore a portion of it cannot be used for drying, nor can a segment of the pond be taken out of service for maintenance and cleaning. The Backwash Pond is located within the 100-year floodplain, making it vulnerable to damage and potential discharge to Bear Creek with significant storm events. The plant site has limited space available, making it unlikely that significant improvements to the system can be made. Decant water is pumped from this pond to the reservoir, and solids are removed from this pond by an outside contractor Distribution System The Genesee water distribution system is relatively large with extensive piping, several pump stations, and two 600,000-gallon water storage tanks. Based on the size of the system and the volume of water storage, which is required to meet both operational and fire storage requirements, it is anticipated that water ages (time between treatment and use) in the distribution are relatively high. Treated water is introduced into the south side of the distribution system, and water ages are expected to be highest at the school site that is located north of Interstate I-70. The Crossings Pump Station. A series of pump stations are required to transmit treated water into the distribution system. 2.3 WATER SYSTEM LOSSES AND UNACCOUNTED WATER Genesee monitors their water diversions and treated effluent returns very closely and for several purposes, one of which is to identify potential water system losses. Essentially, there is one pipe withdrawing water from Bear Creek, which supplies potable water to the customers of the District, and one pipe delivering customer return flows, or treated effluent back to Bear Creek. Appropriate metering is in place on both the supply line as well as the return line. Additionally, there are provisions for duplicate or check metering for each at nearby locations to the metering of record. Metering of record is logged daily with check/duplicate metering comparisons performed on a monthly basis. Calibrations and accuracy testing is performed periodically as needed. Relevant to potential water loss within the drinking water transmission and distribution system, water supply metering is constantly compared to effluent metering throughout the year. However, for the particular purpose of determining system water loss, the months of November through February are used for comparison since during this time period there is no outside water use and there is limited potential for collection system inflow/infiltration due to precipitation. Genesee provided monthly metering records and graphs for November through February spanning over six years, included in Appendix B. As indicated in the charts and graphs, return flows are typically greater than 95%, a strong indication that water loss is less than 5%, but most likely on the order of 2-3% considering consumptive use. 5 November 2014

17 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District In addition to water monitoring, isolation tests are periodically performed to determine whether further leak testing is required by an outside contract service. 2.4 VULNERABILITY ASSESSMENT Genesee completed a Vulnerability Assessment in 2004 in accordance with the Bioterrorism Act of 2002, and recently updated the document in The updated document was submitted to the Environmental Protection Agency (EPA) and Genesee received a Certification for the Vulnerability Assessment and the associated Emergency Response Plan. A copy of the Certification is included in Appendix C. Practically all measures identified in the Vulnerability Assessment have been implemented at this time. 6 November 2014

18 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 3 WATER DEMANDS AND PLANT CAPACITY A fundamental element of the preliminary design is establishing system water demands and the recommended water treatment plant capacity. These evaluations were completed as part of the Water System Facilities Master Plan included in Appendix A, and is presented below. 3.1 WATER SYSTEM DEMANDS Customers consist primarily of residential and commercial users, with both indoor and outdoor landscape irrigation uses. The outdoor water demand fluctuates with the irrigation season occurring between May and October. Historically, annual water use has ranged from 439 acrefeet in 2000 (including 40 acre-feet used to fill and refill a reservoir during construction) to 370 acre-feet in Water use in 2012 and 2013 averaged 400 acre-feet, or about 0.36 million gallons per day (mgd). Table 3-1 shows a summary of historical average and peak water demands. Demand Table 3-1: Genesee Historical Water Demands Million Gallons / Day Acre-feet / Month Historical Average Demands Winter Average Historical Peak Month Annual Average Day Historical Peak Demand Peak Day Demand 1.0 N/A 3.2 WATER TREATMENT PLANT CAPACITY The rated treatment capacity of the current water treatment facility is 1,400 gallons per minute (gpm), or 2.0 million gallons per day (mgd). However, the plant has consistently been operated at a maximum water production rate of 1,000 gpm (approximately 1.43 mgd) for many years. At a water production rate of 1,000 gpm, the plant is capable of producing enough water to meet water demands in about 8-10 hours during summer months, and in about 6 hours during winter months. The District s historical Peak Day Demand (PDD) is approximately 700 gpm (1.0 MGD). As previously noted, the District is currently at 98% of buildout, and therefore it is not anticipated that there will be significant increased water demands within the District in the future. 7 November 2014

19 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District The planned water treatment capacity of a treatment system can be impacted by a number of factors: Water demands within the District, with treatment capacity designed to meet at a minimum the PDD Operational considerations, such as whether the plant will produce water over a 24-hr day, or only a portion of the day to match facility staffing times The amount of treated water storage in the system and diurnal water use patterns, in order to keep water storage tanks relatively full The capability of the transmission system (pump stations and pipelines) to move the plant s full production capacity into the distribution system; Genesee s transmission and pumping systems have the ability to move up to 1,500 gpm into the distribution system One significant consideration for the Genesee system is the potential for wild fires in the District, which would have a significant impact on the overall water system. Due to the potential for wild fires which would exert significant water demands on the system, a treatment capacity of 1,000 gpm (or 1.43 mgd) was selected for the future water treatment system, which exceeds the historical PDD. This capacity will basically match the current operating capacity of the existing WTP. The Larkspur Pump Station along the transmission line. The transmission system is capable of moving 1,500 gpm into the Genesee distribution system. 8 November 2014

20 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 4 RAW WATER QUALITY 4.1 RAW WATER SOURCE AND CONSIDERATIONS The raw water source for the water system is Bear Creek, with water being pumped to the Genesee Reservoir for storage prior to being treated at the District s new Advanced WTF. Genesee will be able to supply water either directly pumped from Bear Creek, or from the Genesee Reservoir, for raw water supply. Genesee typically uses water from the reservoir since it has lower turbidity due to natural settling and more stable water temperature and alkalinity, however they switch to direct supply from Bear Creek during times when turbidities or TOC are elevated in the reservoir water. Water quality conditions may deteriorate in the future as the Genesee Reservoir ages. In addition, raw water quality in Bear Creek may deteriorate as further upstream development occurs, or due to potential beetle kill of trees or forest fire. Genesee has not historically seen significant algae growth in the reservoir, however there may be more algae growth in the future. 4.2 ANTICIPATED RAW WATER QUALITY The Genesee Raw Water Reservoir A summary of Genesee s water quality is presented in Table 4-1. Bear Creek s water quality is similar to many mountain water streams in that it has low TDS and alkalinity, highly variable water temperatures with low winter temperatures, and variable ph. 9 November 2014

21 Parameter Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Table 4-1: Summary of Water Quality Regulatory Limit (mg/l) Type Average or Range Maximum Temperature (deg C) None None 2-21 N/A ph (s.u.) (see note 1) SS N/A Alkalinity (mg/l as CaCO3) None None N/A TDS (mg/l) 500 SS TOC (mg/l) None None Calcium (mg/l) None None Magnesium (mg/l) None None Hardness (mg/l as CaCO3) 150 Gen Guideline Sodium (mg/l) None None Chloride (mg/l) 250 SS Sulfate (mg/l) 250 SS Fluoride (mg/l) 2.0 SS Nitrate (mg/l as N) 10 MCL Aluminum (mg/l) 0.2 SS Copper (mg/l) 1.3 AL Iron (mg/l) 0.3 SS Manganese (mg/l) 0.05 SS Silver (mg/l) 0.1 SS Zinc (mg/l) 5 SS Antimony (mg/l) MCL Arsenic (mg/l) 0.01 MCL Barium (mg/l) 2 MCL Berylium (mg/l) MCL Cadmium (mg/l) MCL Chromium (mg/l) 0.1 MCL Mercury (mg/l) MCL Nickel (mg/l) None None Selenium (mg/l) 0.05 MCL Thallium (mg/l) MCL Notes: MCL= Maximum Contaminant Level SS= Secondary Standard AL= Action Level BDL = Below Detection Limit Notes: (1) ph is following pretreatment chemical adjustments prior to filtration 10 November 2014

22 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 5 PROJECT GOALS AND ALTERNATIVES EVALUATION 5.1 OVERALL PROJECT GOALS The Water System Facilities Plan included in Appendix A recommended that Genesee construct a new water treatment plant to replace their approximately 32 year old package conventional treatment plant. The construction of a new water treatment facility presented a better financial investment than upgrades to the existing facility. For further information related to alternatives evaluations and project recommendations summarized in this chapter please see Appendix A. The goal of the project is to provide Genesee with a new and robust water treatment system that has the ability to meet future regulations, as well as address potentially deteriorating water quality over time that may result from upstream development, changes in the water shed due to beetle kill or forest fire, and as the District s reservoir ages. The project will provide Genesee with a robust water treatment system that has the ability to meet future regulations as well as address potentially deteriorating water quality over time 5.2 ALTERNATIVE TREATMENT PROCESSES AND PROCESS SELECTION The performance of the existing treatment plant was analyzed and compared to requirements of both current and potential future drinking water regulations. It was determined that a more robust water treatment process would be required to reliably meet current and future water quality regulations during the 30 year planning horizon for the project. Six alternative treatment processes were identified that are capable of meeting Genesee s water treatment goals, including: 1. Process Train 1 - Microfiltration with Powder Activated Carbon Pretreatment 2. Process Train 2 - Microfiltration with GAC Post Treatment 3. Process Train 3 - Microfiltration with Ozone Pretreatment 4. Process Train 4 Granular Media Filtration with PAC Pretreatment 5. Process Train 5 Granular Media Filtration with GAC Post Treatment 6. Process Train 6 Biological Activated Carbon Filtration with Ozone Pretreatment A total Benefit Score was developed for each of the six treatment processes. The Net Present Value of the six treatment processes was also developed based on capital costs and 20 years of O&M costs. Finally, a Benefit to Cost ratio was developed for each of the alternatives by dividing the Benefit Score by the Net Present Value. 11 November 2014

23 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District The highest ranking alternative is Process Train 2, a treatment process that includes coagulation and flocculation followed by sedimentation, membrane filtration (either microfiltration or ultrafiltration), granular activated carbon (GAC) treatment and disinfection. The recommended treatment process was selected compared to alternatives based on the following factors: Had the highest Benefit score Had the highest Benefit to Cost ratio Was cost competitive compared to other options Positions the District well for potential future raw water quality challenges and changing regulations Is relatively simple and reliable to operate Raw water flows through a coagulation and flocculation process to form flocculated particles from the suspended material in the raw water. The water is then treated through the flocculation process, and then flows through plate settlers to remove particulates and the flocculated materials prior to the membrane system. The water is then filtered through microfiltration to remove remaining suspended material in the water. Following filtration, the water flows through GAC columns to further remove organic materials, taste and odor compounds and some micro-pollutants such as pharmaceuticals. The water is then disinfected with chlorine prior to distribution. The plant layout may include space for a future advanced oxidation process in order to provide higher levels of taste and odor compound and micro-pollutant treatment, or for ultraviolet (UV) disinfection. Microfiltration Skids GAC Columns 5.3 ALTERNATIVE SITE LOCATIONS AND SITE SELECTION Two locations for the new water treatment facilities were considered including the existing Water Treatment Plant site, and the site of District s WWTP and Administration Building. An option that would split the new water treatment facilities between the two sites was also considered. The relative locations of the existing WTP and WWTP/Administration Building sites are shown in Figure 5-1. The three options were evaluated considering cost, operational issues and institutional issues. The preferred alternative is to construct the new water treatment facilities at the site of the District s WWTP and Administration Building. This alternative presented significant advantages in reducing capital costs since the WWTP may be used for residuals management, thereby preventing construction of separate residuals handling facilities, and consolidating all plant operations at a single location. 12 November 2014

24 GENESEE WASTEWATER TREATMENT FACILITY H DIST: 2,400FT (APPROX) Z DIST: 375FT (APPROX) GENESEE WATER TREATMENT FACILITY OVERALL SITE PLAN FIGURE 5-1 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN RELATIVE LOCATIONS OF THE WATER AND WASTEWATER PLANTS SCALE: 1"=600'

25 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 6 WATER TREATMENT PROCESS DESIGN This chapter describes the treatment processes and facilities, and establishes design criteria for the treatment system. 6.1 WATER TREATMENT PLANT CAPACITY AND PROCESSES The water treatment facility will be designed to treat water at a production rate of 1,050 gpm (1.51 mgd), and for a net production rate of 1,000 gpm considering lost waste streams. It is anticipated that backwash wastes will be recovered through backwash recycling. This treatment process is shown in Figure 6-1. Water is first treated through the flocculation process, and then flows to plate settlers to remove particulates and the flocculated materials prior to the membrane system. The water is then filtered through MF/UF to remove remaining suspended materials in the water. Following filtration the water flows through GAC columns to further remove TOC, and to remove taste and odor compounds and micro-pollutants. Water is then disinfected with UV treatment (optional) and chlorine disinfection. The water is then pumped into the distribution. 6.2 TREATMENT GOALS AND PLANT PERFORMANCE The overall goals for the treatment processes are to produce treated water that will meet drinking water regulations and provide an appropriate level of treatment considering the raw water quality. The new treatment system will be designed to provide positive barriers, and in some cases multiple barriers, to various classes of contaminants. In addition to providing finished water that meets all primary standards, the finished water should have an appropriate ph and alkalinity, have an acceptable mineral content, and be stable and non-aggressive. In addition to the treatment considerations, there are a number of other technical and financial considerations that are factored into the developed treatment processes, as summarized in Table 6-1. Table 6-1: Summary of Treatment System Considerations for the Genesee Advanced WTF Treatment Considerations Technical Considerations Financial Considerations Cold water & low Flexible treatment Capital costs alkalinity processes Presence of micropollutants Waste stream generation O&M costs (pharmaceuticals, personal care product, etc.) Relatively high TOC Ease of operation Labor Potential for Taste and Odor to develop Solids handling Solids handling 13 November 2014

26 ph ADJUSTMENT SODA ASH COAGULANT 1st STAGE 2nd STAGE 3rd STAGE INCLINED PLATE SETTLERS CHLORINE SODA ASH RAW WATER SLUDGE COLLECTION UV AOP UV AOP FLOCCULATION PLATE SETTLERS MICROFILTRATION GAC COLUMNS BYPASS UV DISINFECTION OR ADVANCED OXIDATION PROCESS CHLORINE DISINFECTION FLOCCULATION CLARIFICATION PLATE SETTLERS FILTRATION MICROFILTRATION POST TREATMENT GRANULAR ACTIVATED CARBON COLUMNS POST TREATMENT DISINFECTION, T&O AND MICRO POLLUTANT PATHOGENS TURBIDITY / PARTICULATES ORGANICS TASTE & ODOR (FOR AOP) MICRO-POLLUTANTS (FOR AOP) FIGURE 6-1 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN MEMBRANE FILTRATION WITH GAC POST TREATMENT

27 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District There are several regulations that are important in the design of the Genesee Advanced WTF. These regulations include: Safe Drinking Water Act (SDWA) Surface Water Treatment Rule (SWTR) and Enhanced Surface Water Treatment Rule (ESWTR) Disinfection Byproduct Rule (DBPR) Enhanced Coagulation Treatment Technique/Rule The Backwash Recycle Rule 6.3 WATER TREATMENT PROCESS FLOW DIAGRAM AND DESIGN CRITERIA A detailed Process Flow Diagram for the system is shown in Figure 6-2. The process shows the major treatment processes throughout the plant. Specific details related to the MF/UF system will be added once the equipment manufacturer and equipment are selected. A detailed Design Criteria sheet is shown in Figure 6-3, summarizing the basic criteria and basis of design for the major treatment processes. 6.4 TREATMENT FACILITY FLOOR PLAN The Genesee Advanced WTF will be an approximately 8,900 square foot facility with three major areas including the Administration area, the Chemical Storage area and the Process area. A process floor plan for the facility is shown in Figure 6-4. The Administration area is located on the south side of the building to provide natural lighting and snow melting at the main entrances into the facility. The Chemical Storage area is separate from the Administration area and the Process area. Access has been provided to the Chemical Storage and Process areas on the west side of the building. 6.5 HYDRAULIC PROFILE A hydraulic profile for the Advanced WTF is shown in Figure 6-5. Raw water to the Advanced WTF comes from the Solitude Water Tank. A flow control valve is required at the head of the facility to control flow into the plant. After the raw water flows through the raw water pipeline and goes through coagulation, the water will then flow through the flocculation and sedimentation basins with minimum hydraulic losses. The water then flows into the Settled Water Tank which will provide a hydraulic wide point, and also provides equalization between the pretreatment processes and the membrane system. The water level in the Settled Water Tank varies based on plant operations, but will provide adequate suction head to the MF/UF system pumps. The MF/UF provides pressure to pump the water through the membranes, GAC columns and UV reactor, and finally into the clearwell. Finally, the Finished Water Pumps distribute the treated water into the distribution system. 14 November 2014

28 TO CITY DISTRIBUTION SYSTEM FROM GENESEE RESERVOIR / BEAR CREEK LARKSPUR PUMP STATION AND CLEARWELL BASE PUMP STATION INLINE STATIC MIXER COAGULANT FINISHED WATER 10"FM SODA ASH ACID SOLITUDE TANK CAUSTIC FM RAW WATER M FLOW CONTROL GRANULAR ACTIVATED CARBON BACKWASH MICROFILTRATION SKID A OR B BACKWASH WASTE GRANULAR ACTIVATED CARBON UNIT 1 VALVE RACK GRANULAR ACTIVATED CARBON UNIT 2 FINISHED WATER GRANULAR ACTIVATED CARBON TREATED WATER BACKWASH SUPPLY FROM PLANT POTABLE WATER SYSTEM FM FM BYPASS UV UNIT 2 UV UNIT 1 CHLORINE FLOURIDE SODA ASH (OPTIONAL FEED POINT) PRESSURE RELIEF FM TO SEWER FM M TO SEWER FLOCCULATION BASINS PROCESS EQUALIZATION TANK POTABLE WATER FROM PLANT WATER SYSTEM TO SEWER FM FM M M BACKWASH RECOVERY TANK BACKWASH RECOVERY PUMPS PLATE SETTLER PLATE SETTLER SEDIMENTATION BASINS SEDIMENTATION BASIN WASTE CLEAN IN PLACE SKID / EQUIPMENT CLEAN IN PLACE TANK SETTLED WATER TANK FM CLEAN IN PLACE PUMP CHLORINE (OPTIONAL FEED POINT) SLUDGE COLLECTOR DRIVE (TYP) RECYLE FEED SLUDGE COLLECTION PUMPS CLEANING SOLUTION CLEANING SOLUTION FEED PUMP SUMP SKID AIR TO PNEUMATIC VALVES BASKET STRAINER RECYCLE FEED SPENT CLEANING SOLUTION SPENT CLEANING SOLUTION NEUTRALIZATION TANK RECYCLE PH / ORP NEUTRALIZATION SKID MICROFILTRATION MODULES AIR REVERSE FILTRATION PUMP TO SANITARY SEWER OPTIONAL REVERSE FILTRATION TANK AIR TO PNEUMATIC VALVES MICROFILTRATION FILTRATE AIR POTABLE WATER FROM PLANT WATER SYSTEM AIR AIR COMPRESSORS LEGEND M M M AIR RECEIVER BACKPRESSURE VALVE MANUFACTURE SUPPLIED EQUIPMENT EXISTING NEW FUTURE PNEUMATIC ACTUATED MOTOR ACTUATED GATE VALVE BUTTERFLY VALVE BALL VALVE 0.01 MICRON 1 MICRON FILTER FILTER 0.01 MICRON 1 MICRON FILTER FILTER CHECK VALVE HYDRAULIC CONTROL VALVE FLOW CONTROL VALVE FINISHED WATER TANK COMPRESSOR NO. 1 COMPRESSOR NO. 2 M FINISHED WATER PUMPS TO PLANT POTABLE WATER SYSTEM MOTOR STATIC MIXER CONSTANT FLOW FITTING MAGNETIC FLOW METER MECHANICAL MIXER PERISTATIC METERING PUMP PNEUMATIC DIAPHRAGM PUMP CENRIFUGAL PUMP SUMP PUMP CONNECTION AT SKID LEVEL SENSOR GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN PROCESS FLOW DIAGRAM REDUCER 3-WAY VALVE FIGURE 6-2

29 GENESEE ADVANCE WATER TREATMENT FACILITY TREATMENT FLOW MAXIMUM NET PRODUCTION MINIMUM NET PRODUCTION MINIMUM RECOVERY RATE (OVERALL PROCESS) MAXIMUM TREATMENT FLOW RATE TO PROCESS MAXIMUM BACKWASH RECOVERY RATE (AT MAX RAW WATER FLOW) RAPID MIX RAPID MIX TYPE VELOCITY GRADIENT (MIN) FLOCCULATORS NUMBER OF TRAINS TOTAL DESIGN FLOW DESIGN FLOW PER TRAIN CONFIGURATION DETENTION TIME PER STAGE (AT MAX FLOW) VELOCITY GRADIENT 1ST STAGE 2ND STAGE 3RD STAGE DRIVE HORSEPOWER PLATE SETTLERS NUMBER OF TRAINS TOTAL DESIGN FLOW DESIGN FLOW PER BASIN DEPTH OF BASIN (SWD) PLATES LOADING RATE EFFICIENCY FACTER WIDTH OF PLATE LENGTH OF PLATE NO. OF ROWS PER BASIN HEADLOSS THROUGH ORIFICES (MAX) TROUGHS NO. PER BASIN TROUGH CAPACITY (EA) HEADLOSS OVER WEIR (MAX) SETTLED WATER TANK OPERABLE VOLUME MEMBRANE TREATMENT SYSTEM MEMBRANE SYSTEM NUMBER OF TRAINS / RACKS FILTRATE CAPACITY PER TRAIN (MAXIMUM INSTALLATION) MEMBRANE SYSTEM RECOVERY (MIN) MAXIMUM FLUX 1-DEG CELSIUS MAXIMUM FLUX 20-DEG CELSIUS MAXIMUM TRANSMEMBRANE PRESSURE SKID INLET PRESSURE (TO FEED PUMPS) MINIMUM DIRECT INTEGRITY TEST PRESSURE FEED PUMPS NUMBER TYPE MAXIMUM CAPACITY TDH AT MAXIMUM CAPACITY HORSEPOWER (EACH) BASKET STRAINERS NUMBER DESIGN FLOW TYPE SCREEN SIZE INITIAL AND BUILDOUT 1.44 MGD (1,000 GPM) 0.22 MGD (150 GPM) 93% 1.51 MGD (1,053 GPM) 0.15 MGD (105 GPM) INITIAL AND BUILDOUT IN-LINE STATIC MIXER 750 SEC -1 INITIAL AND BUILDOUT MGD (1,050-1 GPM) 0.76 MGD (525-1 GPM) 3 STAGE MINS SEC SEC SEC 1 HP INITIAL AND BUILDOUT MGD (1,050 GPM) 0.76 MGD (525 GPM) 9.0 FT 0.3 GPM/FT² 90% 3.5 FT 6.0 FT INCHES MGD (695 GPM) 0.75 INCHES 2,200 GAL INITIAL AND BUILDOUT GPM 95% 35 GFD 60 GFD 26 PSI 8-10 FT 17.5 PSI 2 HORIZONTAL CENTRIFUGAL W/ VFD 575 GPM 105 FT 25 HP MGD (1,050 GPM) AUTOMATIC / HYDRAULIC 300 MICRON GRANULAR ACTIVATED CARBON NUMBER OF COLUMNS TOTAL DESIGN FLOW NOMINAL FLOW PER COLUMN COLUMN DIAMETER HEIGHT CARBON CAPACITY PER VESSEL PRESSURE LOSS ACROSS SYSTEM (RANGE) UV SYSTEM NUMBER OF UNITS NOMINAL FLOW PER UNIT UV DOSE (MINIMUM) CLEARWELL DESIGN FLOW RATE VIRUS INACTIVATION (MIN) REQUIRED CT (FREE CHLORINE) BAFFLING FACTOR CHLORINE CONCENTRATION (MIN) VOLUME REQUIRED FOR CT OPERATING VOLUME TOTAL CLEARWELL VOLUME CLEARWELL HIGH WATER LEVEL CLEARWELL LOW WATER LEVEL FINISHED WATER PUMPS NUMBER OF PUMPS PUMP TYPE PUMP CAPACITY AT DESIGN POINT (EA) TOTAL DYNAMIC HEAD AT DESIGN POINT (TDH) HORSEPOWER WASTE TANKS BACKWASH EQUALIZATION TANK VOLUME (MIN) PROCESS EQUALIZATION TANK VOLUME (MIN) CHEMICAL FEED SYSTEMS COAGULANT TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF TANKS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS PUMPING CAPACITY HYDROCHLORIC ACID TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF DRUMS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS PUMPING CAPACITY INITIAL AND BUILDOUT 2 (1 OR 2 DUTY, DEPENDING ON OPERATION SCHEME) 1.51 MGD (1,050 GPM) 0.76 MGD (525 GPM) 12 FEET 16 FEET 20,000 LBS 2-8 PSI INITIAL AND BUILDOUT 1 (1 DUTY, 0 STANDBY) 1.5 MGD (1,050 GPM) 40 MJ/CM INITIAL AND BUILDOUT 1.51 MGD (1,050 GAL) 4.0 LOGS 5.2 MG*MIN/L MG/L 20,000 GAL 20,000 GAL 40,000 GAL 16 FT 10 FT INITIAL AND BUILDOUT 3 (2 DUTY, 1 STANDBY) HORIZONTAL SPLIT CASE 0.86 MGD (600 GPM) 395 FEET 125 HP INITIAL AND BUILDOUT 10,000 GAL 30,000 GAL INITIAL AND BUILDOUT LIQUID (PACl) 100% BULK 3,500 GAL 2 (1,750 GAL EA) RAW WATER 5-35 MG/L 2 (1 DUTY, 1 STANDBY) GPH LIQUID 30-35% 55 GALLON DRUMS 110 GAL 2 RAW WATER MG/L 2 (1 DUTY, 1 STANDBY) GPH CHEMICAL FEED SYSTEMS (CONTINUED) CAUSTIC SOLUTION TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF DRUMS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS (RAW) PUMPING CAPACITY (RAW) NUMBER OF PUMPS (MEMBRANE CIP) PUMPING CAPACITY (MEMBRANE CIP) SODA ASH TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE NUMBER OF PALLETS DAY HOPPER CAPACITY DAY HOPPER FEED RATE CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS PUMPING CAPACITY SODIUM HYPOCHLORITE TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF TANKS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS (RAW / FINISHED) PUMPING CAPACITY (RAW / FINISHED) NUMBER OF PUMPS (MEMBRANE CIP) PUMPING CAPACITY (MEMBRANE CIP) HYDROFLUOROSILICIC ACID TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF DRUMS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS PUMPING CAPACITY SODIUM BISULFITE TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF DRUMS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS PUMPING CAPACITY CITRIC ACID TYPE ACTIVE STRENGTH STORAGE TYPE OF STORAGE TOTAL WORKING VOLUME NUMBER OF DRUMS CHEMICAL METERING PUMPS APPLICATION POINTS DOSAGE (TYPICAL) NUMBER OF PUMPS PUMPING CAPACITY INITIAL AND BUILDOUT LIQUID 20-25% 55 GALLON DRUMS 110 GAL 2 RAW WATER / MEMBRANE CIP MG/L FOR RAW VOLUME BASED FOR MEMBRANE CIP 2 (1 DUTY, 1 STANDBY) GPH 2 (1 DUTY, 1 STANDBY) 1.0 GPM DRY 100% PALLETS 1 (2,000 LBS) 5.5 CF LBS/DAY RAW WATER OR FINISHED WATER MG/L 2 (1 DUTY, 1 STANDBY) GPM LIQUID 10% BULK 3,500 GAL 2 (1,750 GAL EA) RAW OR FINISHED WATER / MEMBRANE CIP MG/L FOR RAW / FINISHED VOLUME BASED FOR MEMBRANE CIP 2 (1 DUTY, 1 STANDBY) GPH 2 (1 DUTY, 1 STANDBY) 1.0 GPM LIQUID 23-25% 55 GALLON DRUMS 110 GAL 2 FINISHED WATER MG/L 2 (1 DUTY, 1 STANDBY) GPH LIQUID 35-40% 55 GALLON DRUMS 55 GAL 1 MEMBRANE CIP SYSTEM VOLUME BASED 1 (1 DUTY, 0 STANDBY) 1.0 GPM LIQUID 50% 55 GALLON DRUMS 55 GAL 1 MEMBRANE CIP SYSTEM VOLUME BASE 1 (1 DUTY, 0 STANDBY) 1.0 GPM GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN DESIGN CRITERIA FIGURE 6-3

30 126'-6" 77'-6" 49'-0" 25'-0" 52'-6" 15'-0" 29'-4" 10'-8" 16'-6" FW PUMPS 22'-0" FW TANK (40,110 GAL) 21.67x15x16.5H WL UV SYSTEM (2 STACKED UNITS) INFLUENT CHANNEL FLOCCULATION CHANNEL 42'-0" SEDIMENTATION SLUDGE PUMPS CHANNEL GAC SEDIMENTATION PROCESS ROOM MICROFILTRATION SKID B BACKWASH RECYCLE PUMPS BW TANK (6,911 GAL) 13x6x11H WL SKID B MODULES NEUTRALIZATION SKID MICROFILTRATION SKID A SKID A MODULES CIP / EFM SKID CIP / EFM NEUTRALIZATION CHEMICAL FEED SYSTEMS 32'-0" 4'-0" EQ TANK (28,633 GAL) 16x14.5x16.5H WL 19' TOP OF TANK 16'-0" SODA ASH ROOM SPARE CHEMICAL ROOM 141SF CONTROL ROOM WITH SERVERS AND TELEPHONE 250SF LAB 192SF MECHANICAL ROOM 155SF HVAC 18'-2" STORAGE ROOM 106SF CHEMICAL DRUMS WH 11'-0" 15'-6" 6'-0" DF CHEMICAL CHEMICAL ROOM ROOM SODIUM COAGULANT HYPOCHLORITE MEETING/BREAKROOM 163SF FIRE SP RM 70SF SHOWER RESTROOM 17'-8" 6'-4" 11'-6" 5'-0" 6'-0" 6'-8" 12'-3" 8'-0" 11'-0" 9'-4" 12'-10" 21'-10" ELECTRICAL ROOM 242SF HVAC CONDENSING UNIT 5'-6" 6'-0" 6'-8" 12'-3" 9'-4" 4" 11'-0" 22'-2" GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN PLANT FLOOR PLAN 114'-6" 3/32"=1'-0" FIGURE 6-4

31 FLOW DIRECTION LARKSPUR PS CLEARWELL (73,000 GAL) SOLITUDE WATER TANK (60,000 GAL) ABBREVATIONS FF GAC GAL GPM MF PS TOP TOW UV FLOW CONTROL VALVE FINISHED FLOOR GRANULAR ACTIVATED CARBON GALLONS GALLONS PER MINUTE MICROFILTRATION PUMP STATION TOP OF PIPE TOP OF WALL ULTRAVIOLET RAW WATER WITHIN WATER TREATMENT PLANT LEGEND FF = WATER SURFACE ELEVATIONS HYDRAULIC GRADE LINE BACKWASH RETURN FLOCCULATION XXXX.XX NOTES: PLATE SETTLERS SETTLED WATER TANK 1. WHEN PRETREATMENT SYSTEM IS BYPASSED, RAW WATER FEEDS DIRECTLY TO THE MICROFILTRATION SYSTEM. 2. WATER SURFACE ELEVATIONS BASED ON A MAX. INSTANTANEOUS FLOW RATE OF 1,050 GPM. 3. HYDRAULIC PROFILE IS SCHEMATIC ONLY. NOT ALL VALVES, PIPING, FLOW METERS AND APPURTENANCES ARE SHOWN. MF FEED PUMP MF SYSTEM MF VALVE/PUMP RACK STRAINER TOP= MF MODULES GAC COLUMNS PIPING, FLOW METERS AND APPURTENANCES ARE SHOWN. 4. HYDRAULIC GRADE LINE AT SETTLED WATER TANK SHOWN AT MINIMUM TANK LEVEL OF TO PROVIDE REQUIRED PRESSURE TO SUCTION SIDE OF MF PUMPS. 5. HYDRAULIC LOSS THROUGH STRAINER VARIES, HIGH END VALUE OF 4 PSI INDICATED IN PROFILE. 6. HYDRAULIC LOSS THROUGH MEMBRANE VARIES, MID RANGE VALUE OF 19 PSI INDICATED IN PROFILE. BYPASS LINE UV DISINFECTION PRESSURE REGULATING VALVE FINISHED WATER TANK TOW = FINISHED WATER PUMPING FINISHED WATER VALUE OF 19 PSI INDICATED IN PROFILE. FF = HYDRAULIC LOSS THROUGH GAC COLUMN VARIES, TYPICAL VALUE OF 4 PSI INDICATED IN PROFILE GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN HYDRAULIC PROFILE FIGURE 6-5 HYDRAULIC LOSS THROUGH GAC COLUMN VARIES, TYPICAL

32 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 6.6 WATER TREATMENT PROCESS AND SYSTEMS DESIGN Raw Water Supply and Coagulation Raw water to the plant will be supplied from Bear Creek using the Raw Water Intake Pumps and Base Pump Station. The system will be controlled to maintain a relatively stable water level in the Solitude Water Tank, which then feeds the new Genesee Advanced WTF. Raw water piping into the plant will include a flow control valve, a magnetic flow meter and chemical feed points. Acid, base and soda ash will be fed at a point upstream of the coagulant. Limited piping modifications are planned inside of the Advanced WTF to allow either raw water from Bear Creek or the Genesee Reservoir to be supplied to the plant. Planned piping modifications are shown in Figure 6-6. The first step toward effective coagulation is uniform dispersion of the coagulant. Quickly and effectively dispersing the coagulant is critical to neutralization and destabilization of contaminant. Flash mixing is a violent agitation of the water over a short contact time. Flash mixing should occur within a few seconds, and can be accomplished through a mechanical agitator, in-line static mixer, pump impeller, baffling, hydraulic jump, or by other means of agitation. This process usually occurs in small basin or static mixer, immediately preceding the flocculation basin. Detention time ranges from 10 to 60 seconds, where the suspended and dissolved contaminants are destabilized and a nucleus for the floc is formed before entering the flocculation basins. The facility will have the ability to recycle MF/UF backwash water to the head of the plant, prior to the point of flow measurement and chemical addition. Recycled backwash will be limited to 10% of the total raw water supply to the treatment processes Flocculation and Sedimentation The existing Raw Water Intake Pumps and Base Pump Station will continue to be used to supply raw water Coagulation is a commonly used method for treating raw water for potable use. In coagulation, a positively charged metal or other type of coagulant is added for removing particulates and some dissolved contaminants from raw water. When a metal coagulant is introduced to raw water it hydrolyzes, giving rise to positively charged soluble metal ions. These positively charged ions neutralize and destabilize negatively charged pathogenic, particulate and dissolved contaminants from the raw water. Destabilized contaminants then combine together to make larger flocs during the flocculation process. Following coagulation, the water flows to the flocculation system. Flocculation is the application of gentle mixing to increase the aggregation rate of destabilized particulates. During this process, small destabilized particles collide with each other and form progressively larger flocs. The Genesee Advanced WTF will have two trains and use three-stage horizontal flocculators, with each stage having a detention time of approximately 8.0 minutes. The three-stage system will 15 November 2014

33 FIGURE 6-6 MODIFICATIONS FOR RAW WATER SUPPLY

34 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District provide tapered flocculation where the mixing intensity is lowered in each stage as the water passes through the basins. Clarification is the process of removing a majority of the flocculated materials from the water prior to the MF/UF filters. By removing the solids prior to the filtration system, the solids loading to the filtration process is reduced. This helps to maintain filtration production rates, reduce backwash frequency and backwash waste water, and reduce membrane fouling. Plate settlers clarify water by separating the floc developed during the coagulation/flocculation process from water. Flocculated particles are heavier than water and settle out by gravity under the proper conditions. Plate settlers work by providing a sloped surface for the floc material to intersect, and then settle from the water by gravity. The Genesee Advanced WTF will have two trains and a loading rate of 0.3 gpm/sf of plate area, and are anticipated to produce a clarified water that has a turbidity of less than 1.0 NTU 99% of the time. Plate settler clarifier Membrane Treatment System Automatic self-cleaning strainers will be provided for protection of the membrane system. Strainers will be of the perforated screen type with a maximum opening size of and will be located downstream of the MF/UF Feed Pumps. Automatic self-cleaning strainers will remove any suspended solids material greater than µm from the raw water. Water flows through the cylindrical strainer element from the inside and then flows outward, allowing the strainer screen to trap debris on the inner surfaces of the screen. Debris collected on the inner surface of the screen forms a filter cake as it collects more debris. The filter cake causes a pressure differential between the inlet and the outlet strainer and is registered by a pressure differential switch that transmits an electric signal to automatically start a self-cleaning cycle. The self-cleaning process opens an exhaust valve while two stainless brushes sweep the inner surface of the screen. The particles trapped on the screen are dislodged and flush out through the exhaust valve. The Genesee Advanced WTF will have two strainers, each capable of treating the complete plant flow rate of 1,050 gpm. MF/UF systems are available in two basic configurations, either pressure filtration systems or submerged filtration systems. The Genesee Advanced WTF will use a pressure system due to its compact footprint and beneficial hydraulic configuration. The facility will also be provided with two membrane racks or skids, a minimum of two redundant feed pumps, and an air handling system for control of the pneumatic valves and to provide air scour for the backwash process. The semi-permeable (porous) plastic membrane fibers act like a very fine sieve to retain particulate matter, while water and its Multiple Rack Membrane System 16 November 2014

35 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District soluble components pass through the membrane as filtrate, or filtered water. The retained solids are concentrated in a waste stream that is discharged from the membrane system. The pore size of the membrane and the integrity of the sealing mechanism control the fraction of the particulate matter that is removed. MF typically has a pore size of 0.1 to 0.2 microns. UF membranes typically have a pore size of 0.01 to 0.1 microns. MF/UF membrane systems are backwashed on a more frequent backwash cycle than media filtration systems; however backwash waste volume still remains at approximately 5-8% of volume. MF/UF systems also require periodic cleaning with acidic and caustic/chlorine based chemicals to remove fouling and maintain membrane production rates. This backwash cycle is fully automated and usually occurs every minutes, and stops forward filtrate flow for about 2-3 minutes. Although backwashing is performed at a greater frequency, the amount of water used per cycle is significantly less than a conventional treatment process. In many applications, it will occasionally be necessary to perform a quick chemical cleaning process once every 3-4 days to maintain water production and reduce transmembrane pressure. The quick chemical cleaning process is typically either an acidic solution or a caustic solution with chlorine. This process will return the modules to "nearly new" condition and can be performed hundreds of times over the life of the modules. Chemical cleaning (CIP-Clean in Place) is a more rigorous chemical cleaning process and is periodically required to remove fouling that is not removed by the backwash cycle. This is accomplished using acid and/or a caustic-based cleaning solution with chlorine and a soak sequence. The cleaning process requires circulating a series of chemicals through the membrane basins for a specified period of time, typically a unit would be down for 6 to 8 hours for a CIP cycle. Citric acid is commonly used for a mild acidic wash at a ph of 3-4 to remove precipitates and scales, and sodium hydroxide with sodium hypochlorite is commonly used for a mild basic wash at a ph of 10 to remove any biological growth. Following a chemical cleaning, it is necessary to perform a permeate flush of the membranes. The cleaning system consists of a cleaning solution tank, and a circulation pump. Cleaning chemicals are placed in the tank (either dry or liquid), and are mixed to the proper concentration using permeate water from a piped connection to the permeate line. The mixing of the cleaning solution is accomplished by circulating the solution through the system before the cleaning process begins. The unit is equipped with a heater for heating the cleaning solution during a CIP, since chemical cleanings are generally more effective at a temperature of F. The CIP sequence is used to maintain long-term membrane performance. The CIP is initiated based on either trans-membrane pressure (TMP), membrane permeability, volume filtered or time. Under normal operating conditions, the CIP is initiated based on time elapsed Granular Activated Carbon GAC is used to remove a wide range of organic materials and contaminants from raw water sources, and will provide an additional barrier for TOC removal as well as removal of trace contaminants. GAC is usually placed in columns (vertical steel tanks) where water flows through the column from top to bottom. The column would typically be placed downstream of the 17 November 2014

36 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District filtration system to reduce solids loading to and bacterial growth within the GAC column. Contact times inside the GAC columns can range anywhere from 5-30 minutes, depending on what contaminant is being removed and the concentration of the contaminant in the raw water. Once the GAC is exhausted, it may either be regenerated at an off-site facility, or disposed of in a landfill. Regeneration is the process of super heating the GAC material to high temperatures to burn off organic compounds that have accumulated, and to reactivate adsorption sites in the carbon. The decision as to whether regenerate or simply dispose of GAC is largely based on economics and proximity to regeneration facilities, and for Genesee it is anticipated that GAC will be disposed of to a landfill and replaced. GAC will be located in pressure columns located downstream of the MF/UF system The Genesee Advanced WTF will contain two GAC columns, each holding 20,000 lbs of carbon and with an empty bed contact time of approximately 15 mintues. The system will be designed to allow either all, none, or a portion of the filtered water to flow through the GAC columns, and the GAC columns may be operated either in parallel or in series as long as the flow rate through an individual unit does not exceed 525 gpm. The GAC columns must be backwashed occasionally once the differential pressure increases to an established set point Finished Water Storage and Disinfection Disinfection will be provided in the clearwell following filtration. The primary objective of disinfection is to ensure inactivation of pathogens and viruses. The inactivation contact time required is dependent on the water temperature, ph and the disinfectant concentration. As water temperature decreases the required contact time increases. When free chlorine is used, the required contact time increases as the ph increases. For a MF/UF treatment system, CDPHE s requires that the disinfection system be designed to achieve 4.0 long inactivation of viruses. Genesee has historically and will continue to use free chlorine for system disinfection and to maintain a residual in the distribution system. A baffling factor of 0.5 will be used for design of the clearwell. The baffling consists of a perforated inlet baffle and serpentine intra-basin baffles. These parameters were used for the Genesee Advanced WTF to calculate the required clearwell volume of 40,000 gallons, which includes approximately 20,000 gallons for disinfection and 20,000 gallons for operational volume. A minimum chlorine concentration of 1.0 mg/l is required to be maintained. Genesee will also re-locate a UV system located at the existing facility to the new Advanced WTF; however the District will not need to operate this unit to meet disinfection requirements. 18 November 2014

37 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Finished Water Pumping The finished water pumping system will consist of three horizontal split case pumps, two to serve as duty pumps and one for standby. Each of the finished water pumps will be 125 Hp and will be equipped with a variable frequency drive. The piping system will include isolation valves both on the suction and discharge side of the pumps, a check valve on the discharge side of the valve, and an air and vacuum valve and magnetic flow meter on the combined discharge line. The Finished Water Pump system will also include a pressure relief valve to prevent over pressurization of the line and protection from a surge event. Computer modeling was performed for the distribution system to develop system head curves for a variety of operating conditions. The pump system curves are impacted by the water level in the clearwell, the water level in the Larkspur Pump Station, and the flow rate of the water being pumped. The system curves developed from the hydraulic modeling and selected pumping curves for each set of the pumps are presented in Figure Chemical Feed Systems The chemical feed systems will provide storage and pumping for chemicals throughout the plant. In most cases, the chemical feeds will be flow paced. The chemical feed systems include: Caustic solution for adjustment of raw water ph, and for membrane CIP Hydrochloric acid for adjustment of raw water ph Soda ash for adjustment of the raw water alkalinity Coagulant for charge neutralization and the coagulation process Sodium hypochlorite for disinfection and for membrane CIP Hydroflourosilicic acid for providing fluoride in the treated water Citric acid for membrane CIP Sodium bisuflite for membrane CIP The chemical storage rooms will be grouped together at the south end of the building and west of the Administration area, as shown in Figure 6-3. All of the chemical feed systems will have a separate chemical feed room, with the exception of one room that will house a number of 55- gallon drums including the caustic and acid for raw water ph control, and hydroflourosilicic acid. The hydroflourosilicic acid system will include a loss of weight scale. Each chemical feed room will be provided with an eyewash station. The coagulant and hydrochloric acid systems will include bulk chemical storage tanks due to the large volumes of chemical that will be used. The sodium hypochlorite storage room is an H occupancy and will be provided with fire rated walls and a fire sprinkler system. 19 November 2014

38 FIGURE 6-7 GENESEE WATER & SANITATION DISTRICT PRELIMINARY DESIGN FINISHED WATER SYSTEM/PUMPING CURVES

39 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District The soda ash feed system will consist of a dry feed system. Soda ash will be delivered through trucked deliveries of pallets containing 50 lb bags. The soda ash system will consist of a volumetric feeder with day hopper, solution tank, dust collector system and appurtenances. Soda ash will be loaded manually into the day hopper. The soda ash system will be provided with one volumetric feeder since it is not a critical chemical feed system. All primary chemical feed systems will be provided with a redundant metering pump. Spare metering pumps will be provided for the membrane CIP transfer pumps. Design criteria for the chemical feed systems are based on the design dosage of the chemical, storage facilities that are needed and backup requirements. Design criteria for the chemical feed systems are presented in Figure Waste Tanks Two waste handling tanks will be located inside of the plant floor space to handle wastes generated by the plant, as summarized in Table 6-2 below. The backwash waste may be recycled to the head of the plant or discharged to the sewer system based on operator preference. The clarifier waste stream and GAC backwash will not be recycled to the head of the plant as these waste streams may adversely impact the treatment processes, and therefore will only be discharged to the sewer. In both cases equalization tanks are required to minimize high instantaneous flow rates to either the head of the plant or to the sewer system. Table 6-2 Waste Handling Tanks Tank Backwash Equalization Tank Process Equalization Tank Volume Design Basis (Gallons) 15,000 Sized to handle up to fifteen system backwashes 40,000 Sized to handle concurrent backwashes of both GAC columns and solids removal from both clarifier tanks Discharge Location Recycled to raw water or discharged to sewer Discharged to sewer Plant Water System The plant water system is a critical part of the process system. In addition to supplying water for typical potable demands, the plants potable water system supplies water to chemical feed systems, pump seal water and hose bibbs. The plant water system also provides backwash water to the MF/UF system and the GAC columns. The potable water/plant water system inside of the plant will be supplied by two sources, the first being a connection to the potable water distribution system located along Bitterroot Lane, and the second being a connection to the Finished Water Pump discharge line. Both sources will be 20 November 2014

40 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District connected to provide backwash water to the MF/UF system and the GAC columns so that water may be taken from either or both sources based on operator preference, and also to guarantee adequate water supplies for these processes which includes high instantaneous flow rates. A schematic of the plant water system is shown in Figure 6-8. The potable water plumbing system is further discussed in Chapter RESIDUALS MANAGEMENT The Genesee Water Treatment Plant will produce several waste streams, including liquid, mixedliquid and solid wastes Summary of Waste Streams and Disposal General Description of Waste Streams Liquid and mixed-liquid waste streams generated by the Genesee Water Treatment Plant include: Sanitary waste (restrooms and plant sinks) Plant washdown / cleaning water On-line instrumentation flows Clarification treatment process underflow (mixed liquid and settled flocculant solids) Backwash waste from the MF system (mixed liquid and filtered flocculant solids) Spent MF membrane cleaning fluids Backwash water from the GAC process These liquid and mixed-liquid waste streams will be discharged to the Genesee Wastewater Treatment Plant for (WWTP) further treatment. The largest flows to the sanitary sewer come from the clarifier underflow wasting and MF backwash operations, which includes significant volumes of mixed-liquid containing flocculant solids. These waste streams should be equalized and discharged at a gradual rate to prevent sudden hydraulic and solid loads to the WWTP. The spent MF membrane cleaning fluid is a relatively minor flow when averaged across the course of a year, however the chemical solution must be properly neutralized and discharged at a gradual rate. The sanitary, plant washdown, and on-line instrumentation have relatively minor flows. There are also several solid waste streams that will be produced by the Genesee Advanced WTF. These waste streams consist of used membrane elements from the MF/UF system, UV lamps and used GAC. Liquid Waste Streams Generation and Handling Liquid waste streams are generated from a number of treatment processes, and from general plant maintenance. 21 November 2014

41

42 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Sanitary Waste Domestic sanitary waste will be discharged to the sanitary sewer and be treated at the Genesee WWTP. Sanitary flows originate from use of toilets, sinks, showers, and the laboratory and pilot testing facilities. Typical anticipated flow rates are presented in Table 6-3. Plant Washdown The plant washdown water is generated from water used to clean the plant. These flows typically enter the sewer system through floor drains, and may also contain a cleaning agent. Typical anticipated flow rates are presented in Table 6-3. On-Line Instrumentation Several of the on-line instruments (such as turbidimeters and chlorine analyzer) require a constant sample flow through the instrument for measurement of the water quality parameter. These process waste streams are discharged to the sanitary sewer. Typical flow rates are presented in Table 6-3. Spent MF Membrane Cleaning Fluid The spent MF membrane cleaning fluid will primarily consist of acid and base discharges from cleaning the MF membranes. Either citric acid, phosphoric acid or hydrochloric acid are used for acid cleans, while caustic soda with sodium hypochlorite are used for caustic and chlorine cleans. The MF clean-in-place system is automated, including batching of the cleaning solutions for use, and neutralizing the acid, base and chlorine in a neutralization tank after the chemicals have been used for cleaning. Discharge of this stream to the sewer is also automated and controlled by the SCADA system to prevent excessive flow rates to the sewer. Typical flow rates and waste characteristics are summarized in Table 6-3. Clarifier Treatment Process Underflow One of the most significant waste streams is the settled solids from the clarifier process. The mixed liquid-solids stream is typically removed from the basin once every two to four days. The flow will be captured in an equalization tank and slowly discharged to the sewer system to prevent excessive instantaneous flow rates to the sewer and loads to the WWTP, and will be automatically controlled by the SCADA system. This stream contains a significant solid load from the coagulation/filtration process. Typical flow rates and solids loading rates are summarized in Table 6-3. MF Backwash Stream The MF system requires backwash of the membranes once every 15 to 60 minutes to keep the membranes from losing production capacity or experiencing significant fouling. Once again, the 22 November 2014

43 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District backwash water consists of a mixed liquid-solids stream. The flow will be captured in the Backwash Equalization Tank and either slowly recycled to the raw water and recovered, or discharged to the sewer system to prevent excessive instantaneous flow rates to the sewer and loads to the WWTP, and will be automatically controlled by the SCADA system. This stream contains a significant solid load from the coagulation/filtration process. Table 6-3 outlines the volume, waste characteristics, and disposal method for the waste streams described above. 23 November 2014

44 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Table 6-3: Liquid and Mixed Liquid-Solids Waste Stream Descriptions Stream Volume Flow Rate Characteristics Disposal Method Notes Sanitary Waste Plant Washdown On-line Instrumentation Spent MF/UF System Cleaning Fluid Typical <1,000 gpd (<20 gpm peak typical) Typical <1,000 gpd (<20 gpm peak typical with one hose being used) Approximately 1,500-3,000 gpd (1-2 gpm for all instruments) Avg. Day = 1,060 gpd Peak Day = 6,300 gpd *See Note (1) Domestic sewage Potable water, possibility of cleaning agents Similar to raw water and finished potable water, limited instrumentation reagents Acidic, caustic and sodium hypochlorite cleaning agents: - ph neutralized to , residual chlorine < 5 mg/l BOD 5 loading from citric acid: - Average = 22.1 lb/day - Peak = lb/day To sanitary sewer To sanitary sewer To sanitary sewer To sanitary sewer (chemically neutralized as required) Automatically neutralized, and automatically or manually discharged to sewer system. Must be discharged within a 24 hour period, to allow tank to be prepared for the next cleaning solution preparation. Clarifier Treatment Process Underflow MF/UF Backwash Waste GAC Backwash Avg. Day = 400 gpd Peak Day = 5,200 gpd *See Note (3) Avg. Day = 18,950 gpd Peak Day = 74,750 gpd *See Note (5) Avg. Day = 1,000 gpd *See Note (6) *See Note (2) Avg. = 30.8 lb/d Peak = lb/d *See Note (4) Primarily liquid, limited solids from filter removal (most solids are assumed to be removed in the clarifier) Primarily liquid, limited solids from GAC columns To equalization tank and sanitary sewer To equalization tank, then to sanitary sewer or recycled to raw water To equalization tank and sanitary sewer Automatically or manually discharged to sewer. Combined with GAC backwash waste. Must be discharged within a 48 hour period. Automatically or manually discharged to sewer or recycled to process. Must maintain discharge rates. Automatically or manually discharged to sewer. Combined with clarifier waste. Must be discharged within a 120 hour period. 24 November 2014

45 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Notes for Table 6-3 (1) Calculations assume a maintenance wash once every four days and a CIP once a month. Each maintenance wash includes 1,450 gallons from the solution tank and 1,950 gallons of rinse water. Each CIP includes 1,450 gallons from the solution tank and 4,850 gallons of rinse water. Average Day flow is calculated as the total annual cleaning and rinse volumes divided by 365 days. The Peak Day is calculated as the maximum flow from a single day, includes a single CIP waste volume (1, ,850). (2) The spent MF/UF cleaning fluid estimate assumes 2 skids. Each chemical solution for a CIP clean or maintenance clean may be used to clean both skids. It is assumed that maintenance cleans occur every four days, with 3 out of 4 cleanings being caustic cleans, and 1 out of 4 cleanings being an acid wash. Each caustic maintenance clean uses approximately 1.8 gallons of 25% caustic and 10 gallons of % sodium hypochlorite; an acid maintenance clean uses 35 gallons of 50% citric acid. The full CIP cleaning occurs 12 times per year approximately every 30 days, and includes both a caustic and acid clean. For each CIP, the approximate chemical usage is 34 gallons of 25% caustic, 15 gallons of % chlorine, and 71 gallons of 50% citric. Each 1,450 gallon batch of acid and caustic cleaning fluids are used to clean both (2) skids before being discharged, and also includes a rinse volume (1,950 gallon for a maintenance clean and 4,850 gallons for a CIP). At these chemical usage rates, approximately 5.6 gallons per day of 50% citric acid solution is used, which exerts 22.1 lbs/day of BOD 5. The peak citric acid discharge results following a citric acid CIP, which exerts lbs/day of BOD 5. (3) Maximum solids production rate is based on Peak Day water production of 1.42 mgd (full plant capacity), a turbidity of 15 NTU, and a coagulant (PACl) dose of 25 mg/l. Average solids production is based in Average Day water production (0.36 mgd), a raw water turbidity of 5 NTU, and a coagulant (PACl) dose of 17 mg/l. (4) Under Peak Day water production (1.42 mgd) and solids loading productions (see Note 2), the clarifier mechanism must operate once per day and produces 4,400 gpd at a 1 foot per minute travel rate. Under Average Day water production (0.32 mgd) and solids loading productions (see Note 2), the clarifier mechanism must operate once every 12 days and produces 4,400 gpd at a 1 foot per minute travel rate. (5) Backwash waste is estimated at 5% of daily water production, Average Day= 0.36 mgd, Peak Day = 1.42 mgd (full plant capacity). The backwash volume from each skid, per backwash event, is approximately 675 gallons. The two planned skids in the plant could backwash back to back, however would not backwash at the same time. There would be a minimum of 15 minutes between backwash events. The backwash water would be captured in a tank at the WTP site to allow significant air pockets to escape prior to discharging to the sewer. If the combine backwash from two skids (1,350 gallons) were released to the sewer system over a 15 minute time span, the flow rate to the sewer would be 90 gpm on average. (6) GAC columns are expected to backwash once every 30 days, with a slow and gradual discharge rate to the sewer. 25 November 2014

46 Solid Waste Streams Generation and Handling Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Solid waste streams consist of used membrane elements from the MF system, UV lamps and used GAC. MF Membrane Elements MF/UF membrane elements would typically be disposed of at a landfill. MF/UF membrane elements are expected to have between a seven and ten year life. Modules are primarily made of plastic products that do not require special handling or disposal. In the unlikely event that significant accumulation of hazardous and or radionuclide materials (such as uranium) occur in the membrane elements, they may have to be disposed of at a specialty hazardous waste landfill, however this is consider to have low potential based on Genesee s raw water quality. UV System Lamps UV lamps cannot be disposed of at a landfill and are typically returned to the manufacturer for proper disposal. The UV systems selected by the District contain four lamps each that are expected to last between 18 and 24 months. Granular Activated Carbon (GAC) Once the GAC in the two columns becomes exhausted, it will need to be replaced with fresh GAC. Since there are no local GAC regeneration facilities, it will be more cost effective to dispose of the spent GAC to a landfill and replace it with new GAC than it would to be sending the GAC for regeneration. Limited testing may be required to verify that the GAC will pass tests verifying that it doesn t leach hazardous compounds prior to a landfill accepting the GAC. Residuals Management Plans and Permits Industrial Pretreatment Program Permit The Genesee Advanced WTF will produce a significant source of discharge streams to the Genesee WWTP that could potentially impact plant performance, discharge permit compliance, and residuals management if not handled properly. District staff should determine whether a formal Industrial Pretreatment Program Permit should be issued for the plant. Residuals Management Plan For some new water treatment facilities, the Colorado Department of Public Health and Environment (CDPHE) will require that a formal Residuals Management Plan be developed. CDPHE has historically required Residual Management Plans for water treatment facilities that could produce waste streams that are considered hazardous or have other disposal limitations. While it is not anticipated that a Residuals Management Plan will be required for the Advanced WTF, this will not be known until the project is formally submitted for design review. 26 November 2014

47 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Discharge Permitting The new Advanced WTF will not require a National Pollutant Discharge Elimination System (NPDES) discharge permit, since all waste streams will be discharged to the Genesee WWTP in lieu of being discharged to a water of the State. Genesee may consider maintaining the discharge permit for the Base Pump Station overflow and Backwash Pond at the existing plant site, as these facilities will be maintained as part of the raw water supply system in the future Analysis of Impacts to WWTP A review was completed to determine the potential impact of discharging waste streams from the Advanced WTF to the Genesee WWTP. The WWTP treats wastewater collected within the District s service area. The Genesee WWTP operates under Colorado Discharge Permit System (CDPS) Permit Number CO The WWTP was originally designed to treat a peak month flow of 0.8 mgd and a peak month organic loading of 1,340 pounds of 5-day biological oxygen demand per day (lbs BOD 5 /d). Based on review of the hydraulic profile developed for the 1986 Genesee Wastewater Treatment Plant Expansion by HDR, the peak hour influent design flow appears to be 2.2 mgd. This results in a Peak Hour: Peak Month (PH:PM) peaking factor of 2.5 which will be used to estimate peak hour flows in this impact study. The original construction of the Genesee WWTP included a lagoon, filtration facilities, and a chlorine contact basin. In 1986, the plant was upgraded to include two aeration basins, a secondary clarifier, two aerobic digesters and another chlorine contact basin. The most recent upgrade of the plant occurred in This upgrade included construction of two additional secondary clarifiers, return activated sludge pumps, waste activated sludge pumps, and a dewatering centrifuge. The District has also performed several in-house upgrades to the plant, including the addition of a mechanical screen at the Headworks and modification of the aeration basins to provide an anoxic zone. Influent flow data from 2011 May 2014 was reviewed to determine the current influent flow to the WWTF: Average Influent Flow = 0.23 mgd Peak Month Influent Flow = 0.27 mgd Peak Day Influent Flow = 0.48 mgd Estimated Peak Hour Flow = 0.68 mgd (based on PH:PM peaking factor of 2.5) Firm Capacity of Lift Stations Combined = 2.23 mgd Impact on Existing Facility The existing facility is divided into four main processes. The first is the Pretreatment process that includes the headworks facility, raw sewage pumps, and augmentation/storage lagoon. The second is the Secondary Treatment Process that includes the aerations basins, secondary clarifiers, flow equalization basin, and RAS/WAS system. The third is the Filtration, Disinfection, and Discharge Process that includes the final clarifier, multi-media sand filter, and chlorine contract tanks. The fourth is the Solids Handling Process that includes the aerobic digesters, sludge holding basin, centrifuge, and solids disposal. 27 November 2014

48 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District The following information is a brief description of the impact of adding water treatment plant wastewater at each major unit process at the facility. Preliminary Wastewater Treatment Preliminary wastewater treatment is provided by the headworks. Influent wastewater flows into the headworks via a 12-inch influent sewer. One mechanical screen and one manually cleaned bar screens are installed in series and remove larger debris, or screenings, from the influent flow. After screening, the flow enters a grit chamber, where grit is allowed to settle and is removed. Wastewater leaves the grit chamber by gravity and flows through a parshall flume that provides influent flow measurement. A bypass weir is installed that bypasses wastewater from the influent channel to the channel downstream of the Parshall Flume to avoid overflow of the channel. Currently wastewater overflows the bypass weir under high influent flow conditions. The current Colorado Design Criteria for Domestic Wastewater Treatment Works (WPC-DR-1) requires that screening be installed to meet peak hour influent flow to the facility. The Genesee WWTP was designed and constructed prior to development of the current design criteria may have been designed under less stringent criteria, but the regular bypass overflow experienced at the WWTP indicates that it does not likely meet the current design criteria. Based on hydraulic calculations, it is expected that the bypass weir and influent channel will overflow at approximately the following flow rates depending on how clean the mechanical screen is: Clean Screen Bypass Weir overflows at approximately 1.5 mgd Clean Screen Influent Channel overflows at approximately 2.0 mgd Dirty Screen Bypass Weir overflows at approximately 1.1 mgd Dirty Screen Influent Channel overflows at approximately 1.3 mgd A curb could be installed along the influent channel to contain the wastewater within the channel and direct it through the bypass under higher flow conditions. A curb may be constructed to hold flow within the Headworks channel From the headworks, wastewater flows by gravity to the influent diversion structure, where wastewater can be manually diverted to the raw sewage pump wetwell, equalization tank, or augmentation/storage lagoon. Under normal operating conditions, wastewater is diverted to the raw sewage pump wetwell. Three self-priming, constant-speed, centrifugal pumps are provided to pump wastewater from the wetwell to the aeration basins. Based on curves for the RAS pumps that, according to the District, match the raw sewage pumps, the pumps are designed for a flow of 750 gpm at 25 ft TDH. The pumps operate based on wetwell level. Wetwell level is measured by one ultrasonic level sensor and one bubbler system. The pumps are controlled by operator adjustable level setpoints using the level measured by ultrasonic level sensor. Based on hydraulic calculations and comparison to the provided pump curves, the firm capacity (2 of 3 pumps operating) of the 28 November 2014

49 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District raw sewage lift station is mgd depending on the water level in the wetwell. The raw sewage lift station capacity exceeds the capacity of the headworks and is expected to adequately handle the additional flow through the headworks. Secondary Treatment Flow from the raw sewage pumps can enter either of the two Aeration Basins. These basins operate in the extended aeration mode. Each aeration basin is divided into an anoxic zone for denitrification (biological conversion of nitrate to nitrogen gas), and an aerobic zone for biological reduction of organic material (measured as 5-day biological oxygen demand, BOD 5 ) and conversion of ammonia to nitrate. The anoxic zone is equipped with a submerged mixer and the aerobic zone is equipped with fine bubble diffusers and a mixed liquor return pump. The WWTF has four constant-speed, multi-stage centrifugal blowers to provide process air throughout the plant, including the aeration basins. The volume of air delivered to the aeration basins is manually controlled by the number of blowers in operation and by throttling valves on the inlet of each blower. The blower units that supply oxygen to the aeration basins are located in the Process Building. The Advanced WTF waste streams are not expected to impact the capacity of the aeration basins and was not reviewed. From the aeration basins, wastewater is directed through two 35-ft diameter circular secondary clarifiers that are used to provide liquid/solids separation. Under current operation, the first secondary clarifier (biological clarifier) is being used to settle activated sludge from the flow, and the second secondary clarifier (chemical clarifier) is being used to chemically remove phosphorus. The capacity of the biological clarifier was reviewed based on current Colorado Design Criteria (WPC-DR-1). Average Hydraulic Capacity Less than 700 gal/day/sqft Maximum Hydraulic Capacity Less than 1,200 gal/day/sqft Average Solids Loading Capacity Less than 29 lb/day/sqft Maximum Solids Loading Capacity Less than 40 lb/day/sqft Based on available historical data, the mixed liquor concentration averages approximately 4,000 mg/l with a maximum of approximately 5,000 mg/l. Using the design criteria and historical mixed liquor concentration, the capacity of a single 35-ft diameter clarifier under each criteria is calculated as: Average Hydraulic Capacity 0.67 mgd Maximum Hydraulic Capacity 0.83 mgd Average Solids Loading Capacity (at 4,000 mg/l) = 0.84 mgd Maximum Solids Loading Capacity (at 5,000 mg/l) = 0.92 mgd There isn t adequate information available to determine the hydraulic capacity at which the weirs will submerge and the overall secondary clarification capacity under the current series operation is not readily quantifiable. The capacity is likely greater than that of a single clarifier but design criteria and applicable literature don t address series operation. If additional hydraulic or solids 29 November 2014

50 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District loading causes problems with clarification, the Genesee WWTP may consider operating the secondary clarifiers in parallel as originally designed. Chemical for phosphorus removal could be added to the secondary clarifiers or the third downstream clarifier could be put back into operation for phosphorus removal. Filtration, Disinfection and Discharge The final clarifier provides a redundant liquid/solids separation step so that solids (activated sludge) can be returned to the treatment process and the liquid (secondary effluent) can continue to the next process. Three sludge pumps are used to send the final clarifier sludge to the aeration basins, aerobic digesters, or the sludge holding basin. A single decant pump delivers decant from the final clarifier to the pretreatment process wetwell. Flow from the final clarifier passes to the filtration process in the AWT Building for final removal of suspended solids. Here, a multi-media sand filter is installed, but is not currently being used. Flow is directed from the final clarifier directly to the chlorine contact tank, where chlorine is fed to the secondary effluent to further reduce pathogenic organisms that remain in the wastewater. The chlorine contact tanks consist of two units operating in series that provide sufficient detention time to allow adequate disinfection of the plant effluent. Treated effluent leaving the chlorine contact tank is dechlorinated using sodium thiosulfate prior to flowing through a Parshall flume and to the outfall that discharges into a tributary to Bear Creek. Based on our current understanding of the operations, additional flow from the Advanced WTF is not expected to impact filtration, disinfection, and discharge and was not reviewed. Solids Handling Waste sludge removed in the activated sludge process is pumped by the RAS/WAS Pumps to the aerobic digesters. Here the solids are treated using the aerobic digestion process. Two digested sludge pumps deliver digested sludge from the aerobic digesters to a sludge holding tank. Two centrifuge feed pumps deliver digested sludge from the sludge holding tank to the dewatering centrifuge. The digested sludge is then dewatered with a centrifuge and hauled away for final disposal. The primary solids handling capacity concern for the addition of water treatment plant wastewater is the centrifuge. It is estimated that currently the WWTP produces about 325 lb/day dry solids on average. The District has indicated that the centrifuge can process 30,000 gallons per day or approximately 1,000 lb/day dry solids at a concentration of 4,000 mg/l. It is estimated that the centrifuge must be operated 2-3 days per week to remove solids from the digesters. The solids loading from the Advanced WTF will vary based on operation. It is estimated that the maximum solids loading from the plant discharge will be approximately 300 lb/day as BOD from the microfiltration system CIP and 300 lb/day inert TSS from the clarifier underflow. If both operations occur during the same week, it is estimated that the additional solids load to the 30 November 2014

51 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District digesters may be as high as 500 lb/day. The additional solids from the plant may add more than 3 additional days of centrifuge operation under peak conditions. Under average conditions, the solids loading from the water treatment plant wastewater is estimated at approximately 30 lb/day and shouldn t dramatically impact current solids handling operations. 6.8 LEVEL OF AUTOMATION The new Advanced WTF will be designed to operate without operators being present. The instrumentation and monitoring will allow the system to be operated safely and reliably during times that it is not staffed, and will shut down and/or alarm in the event of problems with equipment or treatment performance. Instrumentation will provide constant monitoring of treatment performance The system will be provided with two modes of operation. In the first mode of operation, the facility will only be allowed to go into production when initiated by an operator. Many facilities prefer to have an operator present during startup to provide a manual check that all processes started properly and that there are no problems with the treatment systems. However, the system will also be provided with the ability to change to a second mode of operation which would allow the facility to start automatically based on either time of the day, or the level of the water storage tanks in the distribution system. 6.9 WATER TREATMENT FACILITY SECURITY The Genesee Advanced WTF will not have a security fence at the time of original construction, but a fence may be installed at a later date when the District implements a comprehensive landscaping plan. Site lighting will be provided to illuminate areas where there are access doors to the building. Interior and exterior security cameras will be provided, along with motion detectors inside the building. Door position indicators will also be provided. The security system will be undertaken outside of the primary construction documents so that the information is not a matter of public record UTILITY SYSTEM CONNECTIONS There are a number of utility connections required for the new Advanced WTF. Phone service and natural gas service both run along Bitterroot Lane, as well as just east of the new plant site. The local utility companies will be contacted to coordinate the correct connection points to the system. Electrical service for a new 500 kva transformer will be served from the power lines running along Bitterroot Lane. The existing water line that transfers treated water from the Solitude Tank to the Bitterroot Pump Station is located approximately 20 feet east of the treatment building. This line will be used to transfer raw water to the plant for treatment, and to transfer treated water into the distribution system. Two tie-ins will be used to connect to this line, one for the raw water and the other for 31 November 2014

52 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District the finished water. A short section of pipe will be removed to physically separate the raw water and finished water systems. Further information regarding site utilities is presented in Chapter ENERGY EFFICIENCY The Genesee Advanced WTF will include cost effective and practical measures to reduce energy use. The new building will have windows on the east, west, and south sides to allow in natural sunlight to help reduce energy usage. Also, energy efficient motors and variable frequency drives will allow efficient energy consumption by the pumps. While the entire building will have heating and ventilation, only a portion of the new building will be designed with cooling. The facility will integrate energy efficient lighting and HVAC equipment. 32 November 2014

53 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 7 RELIABILITY AND REDUNDANCY This chapter addresses reliability and redundancy considerations for the Genesee Advanced WTF. Treatment processes are addressed, as well as system wide considerations such as the overall water system configuration and electrical power supply. This chapter also discusses protection from flooding. 7.1 GENERAL CONSIDERATIONS The Water Quality Control Division of CDPHE outlines criteria for reliability and redundancy for water treatment facilities. These criteria are documented in CDPHE Design Criteria for Potable Water Systems, dated September 1, These criteria (CDPHE criteria) outline general requirements for water treatment facilities, as well as specific criteria for certain treatment processes. While CDPHE criteria address many aspects of the design of a water treatment facility, they do not cover all areas. General engineering practices and conditions specific to each system must be considered when factoring reliability and redundancy into the design of a water treatment facility. Multiple process trains will be provided for redundancy 7.2 OVERALL SYSTEM RELIABILITY AND REDUNDANCY Water Distribution System The Genesee distribution system has 1.2 million-gallon (MG) of potable water storage with 0.6 MG provided in each of the Choke Cherry and Chimney Creek water storage tanks. The volume of potable water storage provides significant flexibility in the event of a power outage or other problems with the water treatment and distribution systems. Genesee also recently entered into an agreement with the Riva Chase District to build an emergency inter-connect between the two systems. All of Genesee s water pumping stations contain multiple pumps to provide redundancy in the event that an individual unit fails Treatment Processes and Systems The major water treatment processes in the water treatment facility will be provided in two parallel trains, so that at least one-half of the facilities capacity remains in service in the event a train is out of service. Reliability and redundancy considerations for each major unit process are discussed in Table November 2014

54 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Table 7-1: JWPP Reliability and Redundancy for Major Treatment Processes Treatment Process/Facility Flocculation Trains Plate Settler Trains Microfiltration Equipment GAC Columns Finished Water Pumps Chemical Feed Systems Redundancy Two parallel and independent units are provided. The flow through a single unit can be increased approximately 50% beyond the nominal flow rate with a minor loss in treatment performance. Two parallel and independent units are provided. The flow through a single unit can be increased approximately 50% beyond the nominal flow rate with a minor loss in treatment performance. A minimum of two units are provided for major equipment including strainers, feed pumps, air receivers and membrane racks. Two parallel and independent units are provided. Three pumps will be provided, with two units having sufficient capacity to move the full treatment capacity of the facility into the distribution system. Two chemical storage tanks will be provided for bulk storage systems. Two metering pumps will be provided for each chemical feed point Electrical Power Supply Genesee has stated that there are very few interruptions of power service at the plant site. There currently is no backup power provided for the Raw Water Intake Pump Station and Base Pump Station, and the Solitude Tank provides limited water storage capacity to feed the plant. The requirement for standby power for pumping and treatment, in the event of utility power failure, is not anticipated at this time since flow of raw water to the Advanced WTF would also likely be interrupted. In addition, there is no backup power at the Larkspur Pump Station which is also required to deliver finished water into the distribution system. Electrical gear will be configured so that an adequately sized backup generator could be connected to the system in the future, if Genesee decided to provide additional backup power at their existing facilities. Limited backup power for controls, actuation of key valves, communications and egress lighting will be provided by an Uninterruptable Power Supply (UPS). 7.3 PROTECTION FROM FLOODING Both CDPHE and Drinking Water Revolving Fund criteria require that structures and mechanical equipment be protected from physical damage from a 100-year flood. The entire Genesee Advanced Water Treatment Facility site and construction activities will be located outside of the 500-yr floodplain, based on FEMA maps. An existing storm culvert also currently discharges just west of the proposed facility location, and will be modified to re-route storm water to the north and around the facility. Storm water management is further discussed in Chapter November 2014

55 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 8 SITE LAYOUT AND DESIGN The purpose of this chapter is to establish site civil design criteria for the project, and present a preliminary plan for the plant site showing major features. 8.1 TREATMENT PLANT SITE SELECTION Several potential sites for the Genesee Water Treatment Plant (WTP) Building were identified for consideration. The potential sites were evaluated considering available space, surrounding land uses, cost, constructability, visibility, aesthetics, site access, existing underground utilities, institutional issues, and environmental considerations. See Appendix D for the site selection technical memorandum that discusses and evaluates each site location. The selected site location for the new Advanced WTF is located within the property boundary of the existing Genesee WWTP that is owned and operated by the Genesee Water & Sanitation District. The new WTP site is located on the east side of Bitterroot Lane between Montane Drive East and the WWTP access road. The existing acre property boundary is located at 2310 Bitterroot Lane, Golden CO at the SW/NW ¼ of Section 30, T4S, R70W. 8.2 SITE LAYOUT AND IMPROVEMENTS Figure 8-1 shows the preliminary site layout and improvements. The plant site is bounded by Bitterroot Lane on the west and Genesee vacant land owned by the Genesee Foundation to the north, south and east. Construction will be limited to within the existing Genesee property limits. The facility will consist of a one single story building will be located on the site. The plant will be constructed in the existing hillside to the north, west and south. A new asphalt parking area and access road will be constructed on the east and south side of the new building. A building identification sign will be located near the entrance to the plant site. Screened enclosures for electrical equipment and trash bins will be located at the south-west end of the building, in the parking area where it will be additionally screened by the hillside and a new constructed retaining wall. Other improvements to the site include exterior lighting, installation of utility lines, and site grading and drainage improvements. 8.3 SITE CIVIL DESIGN CRITERIA New Genesee Advanced WTF site photo A geotechnical investigation was performed by Kumar & Associates. This report summarizes the soil subsurface conditions encountered in the borings, that generally consisted of a few inches of topsoil underlain by overburden soils underlain at depths ranging from about 3 to 5 feet by Gneiss bedrock extending to the full depths explored. The overburden soils consist of sandy lean clay to clayey sand fill and natural soils containing isolated to frequent organic material. The 35 November 2014

56 SITE LAYOUT AND IMPROVEMENTS SURVEY POINT NORTHING EASTING NW CORNER OF PROPOSED WATER TREATMENT FACILITY NE CORNER OF PROPOSED WATER TREATMENT FACILITY SW CORNER OF PROPOSED WATER TREATMENT FACILITY SITE PLAN SCALE: 1"=60' CHECK SCALE: MEASURES 1-INCH FIGURE SE CORNER OF PROPOSED WATER TREATMENT FACILITY

57 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District bedrock consisted of soft, moderately weathered to decomposed Gneiss bedrock extending to the maximum depths explored. The geology and soils present at the site will not present any special or unique construction problems or issues, or present hazards to the facility. The following section summarizes design criteria for the site Site Access, Roadway System and Parking A roadway system has been designed to provide access to the site, as shown in Figure 8-1. Two entrances will be used for drive through access for truck deliveries and maintenance vehicles. Both entrances are located off of the WWTP access road between Bitterroot Lane and the District s Administration Building. The intersections will allow both left and right turns. A parking area will be located on the south side of the new building and bounded by a hillside retaining wall on the west and south. The parking consists of 2 on-site parking spaces, including one handicap-parking space. Additional parking is located at the Districts Administration building approximately 150 feet to the south east. The site roadway connects both entrances to the site, to the parking lot, and provides access to the east and south sides of the plant for deliveries, operations and maintenance Site Lighting Site lighting will consist of two light poles located in the landscaping area southeast of the new building, near the site access. Additionally, two surface lights will be mounted on the retaining wall to illuminate the parking area at the south side of the building. Lights will be located to illuminate the site entrances, east side of the new building, and parking area on the south side of the building. In addition, wall mounted light fixtures will be located around the exterior of the plant near doors. The site lighting plan limits the leakage of light from the site onto Bitterroot Lane, and surrounding residential areas Utilities Utilities to the site will include the following: Potable Water Sanitary Sewer Natural gas Electrical power Cable and telephone lines Water and sewer services are shown on Figure 8-2. An 8-inch water line will be extended to the plant site from the potable water line along Bitterroot Lane. A fire hydrant will be connected off of this 8-inch water line. 36 November 2014

58 20' EMERGENCY EGRESS & UTILITY EASEMENT PER PLAT EX GENESEE WATER AND SANITATION DISTRICT PROPERTY LINE 20' UTILITY EASEMENT PER PLAT NEW WATER TREATMENT FACILITY SITE UTILITIES LEGEND SITE PLAN SCALE: 1"=60' CHECK SCALE: MEASURES 1-INCH FIGURE 8-2

59 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District An 8-inch sanitary sewer line and manholes will run through the parking lot area, and will tie into the sewer line just upstream of the WWTP headworks. Natural gas will be run to the new plant building and a new gas meter will be mounted on the south wall of the building. Cable and telephone lines will be routed to the Advanced WTF from the connections to the southeast. A new electrical transformer will be required for the loads of the new building. This is further described in Chapter Site Drainage and Grading Grading of the plant site will direct runoff to an existing storm drainage swales and pipe culverts that intercept surface flows from the north and west. The runoff through the site will be conveyed by surface flow toward the west across the site access drives. The system will be designed to convey the 100-year flood event across the site Fencing An ornamental security fence may be installed at a future date as part of a comprehensive site landscaping and security project. 37 November 2014

60 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 9 ARCHITECTURAL DESIGN Developing architectural design concepts and material selections are an important component of the project as they impact building function, aesthetics, capital costs, long-term durability, energy efficiency and maintenance requirements. This chapter presents basic information on project architectural requirements and material selections. Alternative building configurations and architectural renderings applying various exterior treatments are also discussed. 9.1 SUMMARY OF BUILDING AREAS The following presents a summary of the Process and Administrative areas required for the new water treatment plant Process Areas Process areas include space to house water treatment equipment, process piping and instrumentation, pumping systems and chemical feed systems. Appropriate clearances should be maintained around equipment for access, maintenance and safety purposes. Exterior doors must be located that will allow for construction, on-going maintenance activities and future equipment replacement. Chemical feed systems will be provided to store coagulant, sodium hypochlorite, ph adjustment chemicals and membrane cleaning chemicals. One chemical will be delivered as a dry chemical in 50 pound bags on pallets. Liquid chemicals will be supplied in a variety of ways including bulk delivery stored in bulk tanks, while other liquid chemicals will be supplied in 55-gallon drums. It is prudent to provide adequate space to store extra drums and pallets of chemical. Chemical feed rooms are typically located on exterior walls to facilitate chemical delivery and transfer activities. In addition to the equipment and piping, a number of water holding tanks will be included inside the water treatment plant. These structures include: The flocculation and sedimentation basins The finished water clearwell A backwash water holding tank for the microfiltration process A process equalization tank for equalizing wastes from the flocculation/sedimentation process and granular activated carbon process before being discharged to the sewer Administrative Areas The administrative areas are critical parts of a functional water treatment plant. Following preliminary programming work completed with District staff, Table 9-1 presents a summary of expected administrative areas for the new plant. 38 November 2014

61 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District We anticipate that one to two staff members will normally be at the plant, with additional staff required during limited times to facilitate equipment/plant maintenance. Facilities Table 9-1: Summary of Expected Administrative Area Rooms Estimated Area (sq. ft.) Requirements Control Room 275 Control room for plant operation with view of the front door and treatment area, general office area with some storage closet and shelving space Laboratory 200 Required for treatment process and finished water quality testing Break Room / Kitchen & Meeting Room 150 Water Room 105 Separate area to house kitchen area and seating area for plant staff, also used as a limited meeting room Room for potable water entry, backflow preventer, water meter, and fire sprinkler riser Storage Space 100 Provide limited storage for various plant supplies Restroom and shower facilities, a Unisex restroom may be Unisex Restroom, 125 provided in lieu of separate Men s and Women s facilities Locker Room/ Shower depending on Administrative Area floor space Mechanical Room 150 Electrical Room 250 Genesee has stated that they prefer to not have any HVAC equipment located on the roof due to aesthetic concerns; this room provides space for interior HVAC equipment Electrical/MCC Room to have exterior access for easy service entry 9.2 BUILDING LAYOUT AND APPEARANCE A building floor plan is presented in Figure 9-1. The west wall of the building and a significant portion of the north wall will be embedded into the side of the hill. In addition, a retaining wall will be required on the south end of the building to allow building access to office areas and space for parking on the south side of the building. The east side of the building will be exposed for the full building height. The office areas will be located on the south side of the building to provide safer entry during the winter. The east facing wall will largely consist of access to process and chemical storage areas. Through preliminary work with both District staff and through public participation at Board meetings, it has been determined that the appearance of the building should generally match that of the Administrative Building. This will avoid introducing a new architectural style and concept to the overall site, and provide for a more consistent and coordinated appearance for the facilities located at the site. Therefore, the new water treatment facility will be constructed with similar architectural concepts and building materials as the Administrative Building. A preliminary rendering for the new Genesee Advanced WTF is shown in Figure November 2014

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64 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 9.3 MATERIALS SELECTION The selection of the architectural materials is based on a combination of factors including: Building function, longevity and maintenance Energy efficiency Capital costs Aesthetics Alternative material selections have been identified for building walls and roofing. Alternative wall construction materials are presented in Figures 9-3 and 9-4, while alternative roofing materials are presented in Figures 9-5 and 9-6. Descriptions of the material including insulation, surface treatments and expected unit costs are presented in the figures for each alternative material Recommended Wall Materials Both the west exterior wall and a significant portion of the north exterior wall will be constructed primarily of concrete in order to serve as a common exterior building wall excavated into the side of a hill, and to serve as a wall for water storage tanks. Above the tank and earth embedded wall areas, CMU block will be used to extend walls to full building height. Exterior surface treatment areas will be applied to the CMU block, and in some instances concrete in areas where significant concrete would be exposed. The east facing exterior wall will be constructed of CMU block; this material is cost effective compared to concrete and will provide a durable wall for treatment process areas that are also capable of bearing significant roofing loads often encountered in water treatment facilities. The exterior south wall for the Administrative areas will also be constructed of CMU for cost effectiveness and long-term durability. Interior walls will be constructed of CMU in select areas where long-term durability and load bearing capacity are desired. Steel framing with drywall will largely be used for the interior wall in the Administration area. In all cases, exterior wall treatments will be applied for aesthetic purposes with only limited areas of exposed concrete at the bottom of walls. Wall material recommendations are summarized in Table 9-2 and presented in Figure November 2014

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69 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Table 9-2: Summary of Wall Material Recommendations Wall Description Material Figure/ Wall Type Exterior- West and North Walls Exterior- East and South Walls Interior- Process Area including Chemical Area Walls Interior- Administrative Area Walls Concrete below and up to tank levels, CMU to full building height CMU to full building height CMU (painted) Steel studs with drywall Concrete- Figure 9-4, Wall 7 CMU- Figure 9-3, Wall 3&4 Figure 9-3- Wall 3&4 N/A N/A Discussion Hardi board, metal panels and limited stone exterior treatments will be applied Hardi board, metal panels and limited stone exterior treatments will be applied CMU will provide a durable wall material with load carrying capability Steel studs with drywall will be cost effective in these areas Recommended Roof Materials In all cases, the roofing material will be constructed of metal seams panels with steel joists. These roofing systems may be installed with pitched roofs, and match the materials used for the Administration Building. Roofing material recommendations are summarized in Table 9-3. Table 9-3: Summary of Roofing Material Recommendations Roof Description Material Figure/ Roofing Type Process and Metal seam panels Figure 9-6- Chemical Areas with galvanized steel Roof Type 4 Administrative Areas joints and deck Metal seam panels with structural insulated panels Figure 9-5- Roof Type 1 Discussion These materials are functional for the area and cost effective These materials are functional for the area and cost effective 9.4 BUILDING CODE AND REGULATIONS Planning and Zoning All building permit applications and site plans must be approved by the Jefferson County Planning and Zoning Division and the Planning Engineering Division prior to building permit issuance. A pre-application meeting should be held with the staff at Jefferson County to determine the schedule and submittal requirements for the project. Current site zoning is P-D. The site is located within the Genesee Planned Development District. 41 November 2014

70 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Architectural Review Committee The project should be submitted for a courtesy review to the Architectural Review Committee for the Genesee Foundation and Genesee Village Homeowners Association Building Permits The building code authority at the project site is Jefferson County. A building permit must be obtained through the Jefferson County Building Department in Golden, Colorado. Separate individual permits may also be required for electrical, plumbing and mechanical. The following are the current adopted building codes for Jefferson County: 2012 Jefferson County Building Code Supplement 2012 International Building Code 2012 International Fuel Gas Code 2012 International Plumbing Code 2012 International Mechanical Code 2014 National Electrical Code 2009 International Energy Conservation Code Fire Protection District Plan Review The local fire district is the Genesee Fire Protection District. The fire district must review and approve all construction drawings prior to the issuance of the building permit. The fire district also separately reviews and approves all fire sprinkler and alarm system drawings. The following are the current adopted codes by the fire district: 2012 International Fire Code; with amendments 2012 International Wildlife-Urban Interface Code; with amendments 9.5 BUILDING CODE DESIGN CONSIDERATIONS Chemical Storage and Use Table 9-4 presents a preliminary listing of anticipated chemicals to be used in the new facility, and their proposed storage quantities. 42 November 2014

71 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Table 9-4: Chemical Classification and Storage Chemical Solution Quantity Classification Storage Allowed in F-2 Aluminum Sulfate (Coagulant) 49% Liquid Solution 3,500 Gallons Non-Flammable, low hazard (NFPA Health: 1) Unlimited Hydrochloric Acid Corrosive (NFPA Reactivity:1), Nonflammable Health Hazard (NFPA Health:3) Sodium Hydroxide (Caustic) Sodium Carbonate (Soda Ash) Sodium Hypochlorite Hydrofluorosilicic Acid (Flouride) Sodium Bisulfite Citric Acid 30-35% Liquid Solution % Liquid Solution 220 Gallons 220 Gallons Corrosive (NFPA Reactivity:1), Nonflammable Health Hazard (NFPA Health:3) Dry 2,000 Lbs Non-flammable Health Hazard (NFPA Health:2) 10% Liquid Solution 23-25% Liquid Solution 35-40% Liquid Solution 50% Liquid Solution 3,500 Gallons 110 Gallons 110 Gallons 220 Gallons Corrosive, Oxidizer Health Hazard (NFPA Health:2) Corrosive (NFPA Reactivity:1), Nonflammable Health Hazard (NFPA Health:3) Non-flammable Health Hazard (NFPA Health:2) Oxidizer (NFPA Flammability:1) Health Hazard (NFPA Health:2) 1,000 Gallons in approved containers 1,000 Gallons in approved containers Unlimited 1,000 Gallons in approved containers 1,000 Gallons in approved containers Unlimited Unlimited Building Occupancy Classification Storage and use of toxic or highly toxic materials will require the chemical storage rooms that exceed 500 gallons (1,000 gallons if storage tanks are approved) will require the classification of the building to be H-4 Occupancy. Since these rooms can be isolated from the remainder of the building, a fire wall separation should be constructed to limit the H-4 classification to only the storage rooms. The remaining portions of the building can be classified as F-2, for the process areas and B for the office areas. Additional H-4 Occupancy Requirements: Any space classified as H-4 must have a fire suppression and fire alarm system, and spill containment areas per 2012 IFC Chapter 60 and Section H-4 Occupancies must have two exit doors with panic hardware and illuminated exit signage. Chemical warning signs shall be placed on doors leading into rooms containing chemical storage including exterior doors as applicable Building Construction Type and Allowable Area The construction of the building is intended to be of Type IIB (non-combustible) construction. 43 November 2014

72 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District The allowable floor areas for this type of construction are 23,000 square feet for both B and F-2 Occupancy classifications. Because the proposed building is under 10,000 square feet in size, no additional occupancy classifications or building fire area separations are required between the process and office areas of the building. The H-4 Occupancy area should be separated by a 2- hour fire wall from all other occupancies Exiting The occupant load of the building is anticipated to be 15 or less persons. A minimum of two exits are required in H-4 occupancy when the occupancy count exceeds 10 persons. On exit is allowed for B and F-2 occupancy. The layout of the preliminary design includes two exits. The maximum Common Paths of Egress Travel (the distance a person must travel before two separate paths to exits are available) are as follows: H-4 Occupancy, sprinklered 75 feet F-2 Occupancy, sprinklered 100 feet F-2 Occupancy, unsprinklered 75 feet B Occupancy, sprinklered 100 feet B Occupancy, unsprinklered 100 feet (below 30 occupants) The maximum Exit Access Travel Distances are as follows: H-4 Occupancy, sprinklered 175 feet F-2 Occupancy, sprinklered 400 feet F-2 Occupancy, unsprinklered 300 feet B Occupancy, sprinklered 300 feet B Occupancy, unsprinklered 200 feet Fire Suppression and Alarm Systems Any space classified as H-4 must have a fire suppression and fire alarm system per 2012 IFC Section , and Chapter 60. No additional requirements for building fire suppression or alarms are required for F-2 or B occupancies unless specifically requested by the local Fire District. In preliminary discussions with the Genesee Fire Protection District, based on the proposed construction type and size, they indicate that they will not require the building to be fully fire-sprinklered, except for the required hazardous chemical storage areas. Full building fire sprinklers or alarm systems can be added as an option to the District, if so desired Plumbing Fixture Counts The occupancy count of the building is anticipated to be 15 or less persons. Based on 2012 IBC Section , a single unisex restroom is being provided per Exception #2. 44 November 2014

73 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District ADA Accessibility Since the plant is a public facility, it is recommend that the office areas of the new building be made fully accessible including the office, laboratory, break room and restroom. The process areas of the new building are not required to be ADA accessible. The occupants of these areas of the building, by nature of their jobs, cannot perform their work with disabilities. Per 2012 IBC Section "spaces frequented only by personnel for maintenance, repair or monitoring of equipment are not required to be accessible. Such spaces include, but are not limited to,...water or sewage treatment pump rooms and stations..." Energy Efficiency The site is located in 2009 IECC Climate Zone 5B. Minimum efficiency requirements for the Building Envelope, Interior and Exterior Lighting and Building Mechanical systems shall be met as part of the building permit submittal. Process Equipment is not included in the efficiency calculations. Use of COMCheck software is recommended for submittal of compliance reports to Jefferson County. 45 November 2014

74 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 10 STRUCTURAL DESIGN 10.1 INTRODUCTION The purpose of this chapter is to define the structural design criteria for the Genesee Advanced Water Treatment Facility. Geotechnical information is based on the "Summary of Findings and General Recommendations" memorandum prepared by Kumar & Associates, dated June 24, Current building codes, wind speed, and snow load are as established by Jefferson County STRUCTURE Concrete will be used for the foundation, tanks and walls in the process area 1) General Description: 2) Roof: 3) Floor: A one-story building of approximately 9,900 square feet housing treatment processes as well as chemical storage, office, and laboratory space. Concrete tanks of various dimensions will be housed within the building. Metal roof deck over metal bar joists. The joists will bear on beams and columns in the interior, and along the east and south faces, and on bearing walls (which also serve as retaining walls and, in some places, tank walls) along the north and west sides. In most places: concrete slab-on-grade. Under large tanks, the base slab of the tank will also serve as a mat foundation. 4) Foundation: 5) Walls: Spread footings. Mat foundation under basins. Concrete retaining walls (and in places tank walls) along the north and west, process area walls. Administration area walls may be metal stud walls, or concrete masonry unit (CMU). Concrete masonry unit will be used in select areas of the Administration area 46 November 2014

75 10.3 DESIGN CODES AND STANDARDS 1) Building Code: Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 2012 International Building Code, International Code Council, with Jefferson County Supplement. 2) Loads: 2010 ASCE 7 "Minimum Design Loads for Buildings and Other Structures," American Society of Civil Engineers. 3) Concrete: a) For non-water-holding areas of buildings and structures: 2011 ACI 318 "Building Code Requirements for Structural Concrete," American Concrete Institute. b) For water-holding structures: 2006 ACI 350 "Code Requirements for Environmental Engineering Concrete Structures," American Concrete Institute. 4) Metals: a) Steel: 14th Edition Steel Construction Manual, American Institute of Steel Construction. b) Aluminum: 2005 Aluminum Design Manual, The Aluminum Association DESIGN LOADS AND CRITERIA 1) Floor Live Loads: a) Process, Electrical, and Mechanical areas: 250 psf, or 100 psf plus actual equipment weight. b) Office areas: 100 psf. c) Stairs, Walkways, and Platforms: 100 psf, or 300 lb point load. 2) Roof Live Loads: Snow loads: 60 psf ground snow load for 7,150 ft elevation. Roof snow load will be calculated in accordance with ASCE 7-10 accounting for exposure and drifting. Minimum roof snow load will not be less than 42 psf per Jefferson County requirements. 3) Wind Loads: In accordance with ASCE 7-10 for 165 mph ultimate wind speed and Exposure "C" for Risk Category III buildings per Jefferson County requirements. 47 November 2014

76 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 4) Seismic Loads: In accordance with ASCE 7-10 with the following data: a) Site class: C b) Mapped MCE spectral response acceleration: 0.2 Second: g 1.0 Second: g c) Spectral response coefficient: 0.2 Second: g 1.0 Second: g 5) Hoists and Rails Design will be in accordance with AISC requirements with impact and horizontal crane forces based on the rated hoist capacity. 6) Earth Pressure and Foundation Recommendations (to minimize costs, we anticipate using processed on-site material rather than imported structural backfill): a) Frost depth: 36" b) Allowable bearing pressure: 5,000 psf. c) Active soil pressure: 45 pcf f) At rest equivalent soil pressure: 55 pcf e) Passive equivalent fluid pressure: 225 pcf f) Coefficient of friction: g) Ground water elevation: Below structure 7) Maximum Deflection Criteria: a) Roof: Live load, L/240 Total load, L/180 b) Floor: Live load, L/360 c) Metal stairs, walkways, and platforms: Live load, 1/4" max d) Members supporting masonry: Total load, L/ MATERIALS 1) Concrete: a) f'c = 4,000 psi. b) Reinforcing, Fy = 60,000 psi b) Cement: Type II d) Minimum wall thickness: 12" for water-holding structures 8" for others 2) Concrete Masonry Units: f'm = 1,500 psi. Reinforcement dowels in concrete 48 November 2014

77 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District 3) Steel: a) W sections: ASTM A992, Fy = 50 ksi minimum. c) Angles, channels, plates, & bars: ASTM A36, Fy = 36 ksi d) Square and tectangular tube: ASTM A500, grade B, Fy = 46 ksi. e) Connections: Bolts: ASTM A325 Anchor rods: ASTM F1554, Grade 36 Welding electrodes: E70XX 4) Aluminum: a) Alloy 6061-T6, with allowable stresses in accordance with the ADM. b) Connections: Bolts: Type 304 stainless steel. Welding filler metal alloy: November 2014

78 11.1 INTRODUCTION Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 11 BUILDING MECHANICAL DESIGN The purpose of this chapter is to define the mechanical design criteria for the Advanced WTF. The facility will require heating, ventilating, air conditioning and plumbing systems as described below. The building contains three general air spaces, the administration area, the chemical storage area and the process area HVAC SYSTEMS The administration area, which consists of offices, laboratories, storage, restrooms and a break room, will be heated and cooled. Temperature setpoints will be 72ºF (adjustable) for cooling and 70ºF (adjustable) for heating. The south offices with an exterior exposure will be served by a five ton gas/dx furnace/split system with associated supply and return ductwork, with ducted return to all spaces. The interior offices will also be served by five ton gas/dx furnace/split system with associated supply and return ductwork, with ducted return to all spaces. An approximately 400 cfm inline cabinet exhaust fan will be used to serve the shower/locker room and restroom. The Electrical Room will contain variable frequency drives. It will therefore need its own cooling system due to the heat generated by the variable frequency drives, which will therefore require constant cooling, unlike the rest of the office space. The system will consist of a five ton split system heat pump. The temperature setpoints for the electrical room will be 85ºF for cooling and 70ºF for heating (the cooling set point will be higher than the rest of the office space due to the fact that the space will not be cooled for human comfort, only to keep the equipment from overheating). The system will have a 100% outside air economizer cycle to use outside air for cooling when the outside temperature is low enough. The process area, which consists of water treatment processes, will maintain a minimum temperature in the space of 55ºF to avoid freezing and provide a minimum level of human comfort. The system will have a 100% outside air economizer cycle to use outside air for cooling when the outside temperature is low enough, however additional cooling will not be provided. The air space will contain three 200 MBH sealed combustion power vented gas fired unit heaters with ducted combustion air and flue. Two 6,400 cfm propeller exhaust fans and associated ductwork, louver, intake louver and motorized dampers will be provided for ventilation. The Finished Water Pumping Room will contain three-125 Hp pumps that are capable of generating significant heat in the small air space. It will therefore need its own cooling system and will therefore require constant cooling. The system will consist of a five ton split system heat pump. The temperature setpoints for the electrical room will be 85ºF for cooling and 70ºF for heating (the cooling set point will be higher than the rest of the office space due to the fact that the space will not be cooled for human comfort, only to keep the equipment from overheating). The system will have a 100% outside air economizer cycle to use outside air for cooling when the outside temperature is low enough. 50 November 2014

79 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District The chemical storage rooms will have their own independent intake louvers with associated duct work and motorized dampers, and independent exhaust fans. These units will supply enough air to the spaces to provide six air changes per hour in order to maintain low chemical concentrations in the air. The rooms will be heated with MBH sealed combustion unit power vented gas fired unit heaters to maintain a minimum temperature of 55ºF to avoid freezing and provide a minimum level of human comfort. The systems will have a 100% outside air economizer cycle to use outside air for cooling when the outside temperature is low enough, however additional cooling will not be provided PLUMBING SYSTEMS The plumbing system for the office area will consist of toilets, lavatories and floor drains for the restrooms; break room sinks and appliance water connections in the break room; and lab sinks for the laboratory. A gas fired water heater with storage tank will supply hot water. The plumbing system for the process space will consist of hose bibbs to supply water for washing down the spaces and carrier water for chemical feed systems. The water services for the hose bibbs and chemical systems will have backflow prevention devices to avoid contamination of potable water in the plant. Floor drains in the process area will also be provided for equipment maintenance, plant cleanup, and to avoid flooding in the event of leaks or failures with piping and equipment. Eye wash stations will be provided in the chemical storage area, the lab and select locations in the process area FIRE PROTECTION SYSTEM A wet pipe fire sprinkler system will be provided for the Sodium Hypochlorite chemical storage room, the only room that has an H hazard classification. The Genesee Fire Protection District has been contacted and has confirmed that this is the only room for which they would require sprinklers. The sprinkler system will meet the requirements of the Uniform Fire Code and Genesee Fire Protection District. 51 November 2014

80 12.1 INTRODUCTION AND OVERVIEW Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 12 ELECTRICAL SYSTEM DESIGN The proposed replacement of the existing WTP with a new MF/UF plant includes electrical and controls work for the new plant construction, maintaining use of the Raw Water Intake Pump Station and integrating it into the new system, and for repurposing the existing Base Pump Station to provide raw water to the new Advanced WTF. Utility power for all facilities will be supplied by XCEL Energy POWER SUPPLY AND GEAR Since the proposed facilities will be all new construction, the main power sources will be new electrical services provided by the local utility company, XCEL Energy. The services will be sized in accordance with anticipated initial demands and foreseeable future requirements. The main switchgear will be bus connected to two low voltage distribution switchboards which will house manual circuit breakers to feed motor control centers, variable frequency drives, and other control and utilization equipment. Preliminary specifications for major switch gear is shown in Table Table 12-1: Preliminary Specifications of Main Switchgear Class Low voltage metal enclosed switchgear, NEMA SG-5, UL 1558 Ratings 480/277 volt, 3 phase, 4 wire, 1000 amps, 100 kaic, Service entrance equipment Main and Tie Breakers Auxiliary Features of each incoming line Low voltage drawout power air circuit breakers, 1000 amp frame, 100% equipment rated, electrically operated XCEL compliant metering compartment, Transient voltage surge suppressor, Digital metering device Raw Water Intake Station and Base Pump Station for Raw Water Supply The existing Base Pump Station includes five vertical turbine, constant speed pumps totaling 330 horsepower of connected load, all of which do not run concurrently. In addition, the station powers and controls two constant speed submersible pumps at the Raw Water Intake Pump 52 November 2014

81 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Station, totaling 70 horsepower of connected load. The existing 480Y/277 volt XCEL service to the station is supplied from a 300 kva pole mounted transformer bank adjacent to the station. The main service disconnect and overcurrent protection is provided by an 800 amp fused disconnect switch located inside the station. Control of the finished water pumps is currently based on maintaining an acceptable water level in the clearwell located below the pump station. The raw water intake pumps are placed in operation either manually or automatically when the plant is placed in operation. The existing pump stations will function satisfactorily to supply raw water to the new Advanced WTF. However, the Base Pump Station has equipment approaching the end of its useful life, and the District has expressed interest in upgrading the pump station so that it is more energy efficient. Long-term improvements to the Base Pump Station are anticipated to include installing three new variable speed vertical turbine pumps, approximately 125 horsepower each, configured as two duty pumps and one standby. All existing vertical turbine pumps will be removed. Variable Frequency Drive (VFD) equipment will be used to control the raw water pump speed. Low harmonic VFD technology will be employed to comply with regulatory power line harmonic distortion limits. It is anticipated that the heat load generated by the upgraded pump station equipment, along with site altitude loss of cooling, will exceed the capacity of the existing station ventilation system. Mechanical cooling in the form of packaged air conditioning will be required to keep the station ambient temperature within the operating parameters of the motors and VFDs. The Solitude Tank will be converted to a raw water tank that supplies the Advanced WTF. The control of the new raw water pumps will be based on maintaining a setpoint level in the Solitude Tank by either changing the number of pumps in operation under the current configuration, or by using speed control based on water level once the VFDs are installed. The Base Pump Station will continue to provide power and control for the Raw Water Intake Pumps. The functionality of these pumps will remain unchanged however, reduced voltage soft starters (RVSS) will be provided to reduce mechanical and hydraulic shocks to the system and equipment. Based on the anticipated loads at the upgraded pump station as shown and tabulated in Figures 12-1 and 12-3, the existing XCEL service is sufficiently sized to supply the load without utility or service equipment modifications Advanced Water Treatment Facility The Advanced WTF will be located adjacent to the existing Genesee Wastewater Treatment Plant and Administration Building located along Bitterroot Lane. At present the latter two facilities are powered by a single XCEL service supplied from a utility pad-mount transformer. As part of the construction of the new facility, the Bitterroot Pump Station will be replaced with finished water pumps within the Advanced WTF. A new XCEL pad-mount transformer and service will be provided for the new facility, and the wastewater treatment plant will continue to be powered from the existing service. 53 November 2014

82 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District From an electrical and control standpoint, the overall proposed MF/UF plant will be made up of the following unit processes: Unit Process 100 Plant Common Components: Includes electrical, controls and instrumentation, operator interface computers, communication network, fire alarm system, HVAC, lightning protection, and system grounding. Unit Process 200 Preliminary Treatment Processes: Includes plant influent flow control, flocculation, sedimentation, backwash return and sludge removal. Unit Process 300 Micro Filtration: Includes all Pall process equipment such as feed pumps, forward filtration, reverse filtration, CIP and CIP chemicals, neutralization, backwash recycle, and process compressed air. Unit Process 400 Finished Water: Includes GAC filtration, UV disinfection, finished water tank, finished water pumps, finished water analysis. Unit Process 500 Treatment Chemicals: Includes chemical storage, chemical feed equipment, spill detection and management, and associated ventilation. The anticipated loads for the above unit processes are shown and tabulated in Figures 12-2 and Based on the total plant load factor, the new service from XCEL to power the plant will require an 800 amp, 480/277 volt, 3 phase service supplied from a 500 kva pad-mount transformer at the plant site. A motor control center located in the plant electrical room will include the main 800 amp service entrance disconnect, surge protection, metering, motor control equipment, power distribution feeders, 208/120 volt transformer and lighting panel. Variable Frequency Drive (VFD) equipment will be used to control the finished water pump speed. Low harmonic VFD technology will be employed to comply with regulatory power line harmonic distortion limits. The heat load generated by the VFDs, along with site altitude loss of cooling, will exceed the capacity of Electrical Room ventilation system. Mechanical cooling provided by packaged air conditioning will be required to keep the Electrical Room ambient temperature within the operating parameters of the VFDs and other electrical and control equipment. MF/UF equipment will be supplied with vendor furnished power and control panels integral to the equipment skids. The power panels will include factory wired VFD and other control equipment requiring only a single point of power feed from the MCC to each panel Backup and Emergency Power There currently is no backup power provided for the Raw Water Intake Pump Station and Base Pump Station, and the Solitude Tank provides limited water storage capacity to feed the plant. The requirement for standby power for pumping and treatment, in the event of utility power failure, is not anticipated at this time since flow of raw water to the Advanced WTF would also likely be interrupted. Electrical gear will be configured so that an adequately sized backup generator could be connected to the system in the future. Limited backup power for controls, actuation of key valves, communications and egress lighting will be provided by an Uninterruptable Power Supply (UPS). 54 November 2014

83 EXISTING POLE MOUNT TRANSFORMERS EXISTING XCEL OH PRIMARY 300KVA 3Ø, 4W 480Y/277 XCEL METER WH EXISTING 800 AMPS MAIN DISCONNECT CT SUBMERSIBLE RW INTAKE PUMP 1 RVSS 35 HP MCP SUBMERSIBLE RW INTAKE PUMP 2 RVSS 35 HP MCP RAW WATER SUPPLY PUMP 1 SEE NOTE 1 RAW WATER SUPPLY PUMP 2 SEE NOTE 1 MCC BPS 480V, 3Ø, 3W, 800A 175/3 175/3 LOW HARMONIC LOW HARMONIC VFD VFD 125 HP 125 HP RAW WATER SUPPLY PUMP 3 SEE NOTE 1 175/3 LOW HARMONIC VFD 125 HP PACKAGED HEATING & COOLING UNIT 20 KVA 40/3 LIGHTING TRANSFORMER 30/ KVA 208Y/120 LIGHTING PANEL PANEL L FIGURE 12-1 BASE PUMP STATION FUTURE ONE-LINE DIAGRAM

84

85 MCC BPS SCHEDULE MCC WTP SCHEDULE TAG NO. DESCRIPTION CONTROL RATED HP RATED KW/KVA VOLTS PH CONNECTED AMPS CONNECTED VA AØ VA BØ VA CØ VA TAG NO. DESCRIPTION CONTROL RATED HP RATED KW/KVA VOLTS PH CONNECTED AMPS CONNECTED VA AØ VA BØ VA CØ VA FEEDER BREAKER RAW WATER INTAKE PUMP RVSS FL-1 FLOCCULATION MIXER 6P VFD RAW WATER INTAKE PUMP RVSS FL-2 FLOCCULATION MIXER 6P VFD FL-3 FLOCCULATION MIXER 6P VFD RAW WATER SUPPLY PUMP 18P VFD FL-4 FLOCCULATION MIXER 6P VFD RAW WATER SUPPLY PUMP 18P VFD FL-5 FLOCCULATION MIXER 6P VFD RAW WATER SUPPLY PUMP 18P VFD FL-6 FLOCCULATION MIXER 6P VFD HVAC HEATING, COOLING, VENTILATION GROUP SP-1 SLUDGE PUMP FVNR SP-2 SLUDGE PUMP FVNR SP-3 SLUDGE PUMP FVNR NOTES 1 TOTALS NON-CONTINUOUS LOAD MOTOR LOAD TRANSFORMER (208Y/120SEC) SUBTOTAL ACTUAL VA DEMAND FACTOR DEMAND VA TRANSFORMER LARGEST STANDBY REMAINDER SUBTOTAL CONTINUOUS LOAD HVAC SUBTOTAL TOTALS VA AMPS PHASE LOADING PHASE BALANCE PANEL AMPACITY OVERCURRENT DEVICE FEEDER AMPACITY NOTES: AØ VA A-B 100.0% BØ VA B-C MIN 421 CØ VA C-A 100.0% 100.0% ACTUAL MF-A MICROFILTRATION SKID A PACKAGE MF-B MICROFILTRATION SKID B PACKAGE CIP CIP SKID PACKAGE AC-1 AIR COMPRESSOR PACKAGE AC-2 AIR COMPRESSOR PACKAGE FW-1 FW-2 FW-3 NOTES 1 TOTALS NON-CONTINUOUS LOAD MOTOR LOAD SUBTOTAL ACTUAL VA DEMAND FACTOR DEMAND VA LARGEST STANDBY REMAINDER SUBTOTAL CONTINUOUS LOAD FINISHED WATER PUMP 18P VFD FINISHED WATER PUMP 18P VFD FINISHED WATER PUMP 18P VFD HVAC HEATING, COOLING, VENTILATION GROUP TRANSFORMER (208Y/120SEC) TRANSFORMER HVAC SUBTOTAL TOTALS VA AMPS PHASE LOADING PHASE BALANCE PANEL AMPACITY OVERCURRENT DEVICE FEEDER AMPACITY NOTES: AØ VA A-B 100.0% BØ VA B-C MIN 589 CØ VA C-A 100.0% 100.0% ACTUAL MCC LOAD CALCULATIONS FIGURE 12-3

86 13.1 INTRODUCTION Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 13 PLC/SCADA SYSTEM AND CONFIGURATION This chapter describes the overall control strategy and the configuration of the Instrumentation and Control (I&C) system to support the operation of the raw water supply system and water treatment facility, and provides the criteria for the control system design for the proposed facilities. Primary objectives of the system are: Safe and reliable operation Maintainability Simple integration with the existing control, SCADA and communication systems Longevity Ease of Use 13.2 SYSTEM CONFIGURATION The control system for the proposed facilities will be in compliance with the District s goal of developing standardized control components Existing Systems Genesee is presently undertaking SCADA and communication upgrades for the District s water and wastewater utility systems in an effort to improve performance, functionality, reliability, and maintainability by unifying the system on common PLC and HMI platforms. Allen Bradley Logix PLC equipment, Rockwell Factory Talk HMI software, and Ethernet or serial data communications are the standards for current and future upgrades. All control equipment for the Base Pump Station and the WTF will be designed with the intent of seamless integration into the overall SCADA system Proposed System The proposed MF/UF system, Unit Process 300, will be provided with a manufacturer s proprietary instrumentation and control system to provide comprehensive automation, monitoring and alarm annunciation of the filtration process and ancillary equipment. The control system includes a master programmable logic controller (PLC) with network and hardwired communications to distributed components in the various subsystems of Unit Process 300. Operator interface with the filtration process control system is provided by an industrial panel mounted personal computer running a Human Machine Interface (HMI) process control application. The software will be fully configured by the manufacturer to provide graphical depiction of the process with live data, interactive operator entry of setpoints and direct control, data logging and reporting, and alarm annunciation. The HMI computer will communicate with 55 November 2014

87 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District the PLC over a local area Ethernet network. Remote access to the control system for troubleshooting and program modification will be provided through a RAS telephone modem and/or through secured internet access. Control of plant equipment and processes, other than Unit Process 300, will be handled with one or more PLCs provided by a system integrator under the general construction contract. Centralized server and HMI computer(s) located in the control room will provide the main operator interface and will reside on a common plant Ethernet network with the MF/UF and plant PLC equipment. Remote internet server access will be provided to allow offsite monitoring by authorized personnel. The upgraded Base Pump Station equipment will be controlled by a PLC employing bidirectional communications with the plant control network. This will permit an operator at the control room to monitor and supervise the operation of both the Raw Water Pump Station and Base Pump Station. Communications with other offsite facilities implemented under future contracts will permit the control room to function as the primary supervisory control location for the Genesee Water and Sanitation District. 56 November 2014

88 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 14 OPINION OF PROBABLE COST 14.1 OPINION OF PROBABLE PROJECT COST The base Opinion of Probable Project Cost for the project is $7,500,000. Applying an accuracy range of +10% to 5% (discussed in further detail below), the Opinion of Probable Project Cost is $7,130,000 to $8,250,000. The detailed Opinion of Probable Project Cost is included in Appendix E Clarifications on Approach, Assumptions and Excluded Items The Opinion of Probable Project Cost is based on cost data developed from previous projects, vendor quotes and recently bid construction projects. Bid climates can vary over time based on overall economic conditions and the availability of Contractors. The costs presented are in terms of year 2014 dollars and no attempt has been made to escalate these costs to a future date. The current evaluation shows that the Wastewater Treatment Plant (WWTP) does not require specific upgrades due to discharge of waste streams from the new WTP. It may be desirable for the WWTP to plan upgrades for specific unit processes such as the centrifuges, to improve reliability and redundancy, however the current system has adequate capacity to handle the additional wastes from the WTP. The WWTP is currently operated with the two clarifiers in series rather than in parallel, which we do not have a performance model for that mode of operation. The solids loading to the clarifier is below typical design criteria for the process if the clarifiers were operated in parallel. Engineering Fees included in the Opinion of Probable Cost have been developed based on basic scope of services for the Services During Construction (SDC) phase, and includes limited onsite observation. The Opinion of Probable Project Cost does not include the following items: A security fence around the building, it is our understanding that the District will not include this item due to aesthetic considerations Landscaping, this will be completed as a separate project Other aesthetic improvements to the WWTP, other than disposal of excess excavation materials on site that could be used for berming Providing fire sprinklers beyond the sodium hypochlorite storage room An additional UV system to provide full redundancy for this treatment process Non-fixed office furniture Laboratory equipment Hoists in the process area to facilitate equipment removal Replacement of pumps and/or electrical gear at the Base Pump Station Work at the existing WTP site other than minor piping modifications 57 November 2014

89 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District Level of Cost Estimate The American Association of Cost Engineers (AACE) has defined different classes of Opinions of Probable Project Cost in an effort to establish the expected accuracy range for various types of cost estimates. The appropriate class is based on the projects status and level of development. A table showing the classes of Opinion of Probable Cost is also included in Appendix E. The Opinion of Probable Project Cost presented in this report is considered a Class 3 estimate, with an expected accuracy of +10% to 5%; this range has been used in the detailed Opinion of Probable Project Cost. The range of +10% to 5% is intended to cover the following items: Unknown bid environment at the time the project goes out to bid Future changes in material unit quantities as the project design advances and is further refined The range is not intended to cover significant changes to the design that may occur during advancement of the design during the project design. 58 November 2014

90 Advanced Water Treatment Facility Preliminary Design Genesee Water and Sanitation District CHAPTER 15 PROJECT SCHEDULE AND IMPLEMENTATION 15.1 PROJECT SCHEDULE The District has established a goal of completing the project by the end of the second quarter of 2017, in order to minimize the time period that they are dependent on the existing treatment plant. To meet this project schedule there can be no delays between various phases of the project. The current project schedule is shown in Figure 15-1, and is based on a six month design period, three months to complete CDPHE approval and receive a building permit with that time period partially overlapped with a three month bid and contract award period, and twenty-two months of construction including system startup PROJECT IMPLEMENTATION Genesee has held three advertised public meetings to discuss the new Genesee Advanced WTF project, and has posted significant documentation regarding the project on the District website. Several architectural renderings were presented to the public for comment, as well as submitted to the Architectural Review Committee (ARC) for the Genesee Foundation review. The project will also have to meet Jefferson County Planning and Zoning requirements. Genesee is seeking Drinking Water Revolving Fund funding for the project, and will have to meet program requirements including American Iron and Steel provisions, completion of an Environmental Checklist and NEPA like process, and the completion of Technical, Managerial and Financial (TMF) Forms. The District anticipates using a traditional Design/Bid/Build approach to implement the construction contract for the project. 59 November 2014

91

92 APPENDIX A WATER SYSTEM FACILITY PLAN

93 Genesee Water Treatment Facilities Master Plan Report FINAL June 2014 Hatch Mott MacDonald 198 Union Blvd., Suite 200 Lakewood, Colorado

94 TABLE OF CONTENTS Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District EXECUTIVE SUMMARY... ES-1 CHAPTER 1 INTRODUCTION PROJECT BACKGROUND... 1 CHAPTER 2 DESCRIPTION OF WATER SYSTEM COMMUNITY DESCRIPTION AND POPULATION TRENDS WATER DEMANDS EXISTING WATER SUPPLY AND TREATMENT SYSTEM CONDITION BASED ASSESSMENT OF EXISTING FACILITIES... 6 CHAPTER 3 WATER TREATMENT PROCESS SELECTION WATER TREATMENT PLANT CAPACITY GOALS FOR THE WATER TREATMENT PROCESSES POTENTIAL TREATMENT TECHNOLOGIES TREATMENT PROCESS TRAIN ALTERNATIVES DEVELOPMENT TREATMENT PROCESS TRAINS EVALUATION AND SELECTION CHAPTER 4 WATER TREATMENT PLANT LOCATION AND CONFIGURATION ALTERNATIVE FACILITY LOCATIONS AND CONFIGURATIONS EVALUATION OF ALTERNATIVE SITES CHAPTER 5 PROJECT IMPLEMENTATION FUTURE PROJECT STEPS ANTICIPATED PROJECT SCHEDULE SUMMARY OF OPINIONS OF PROBABLE COST IMPACTS TO CAPITAL INVESTMENT PLANNING REFERENCES APPENDICES APPENDIX A - CONDITION BASED ASSESSMENT FOR EXISTING WATER SUPPLY FACILITIES APPENDIX B - TREATMENT PROCESS EVALUATION AND SELECTION TABLES APPENDIX C - AMERICAN ASSOCIATION OF COST ENGINEERS (AACE) OPINION OF PROBABLE COST CLASSIFICATION TABLE i FINAL - June 2014

95 EXECUTIVE SUMMARY Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District The Genesee W&S District (Genesee) operates a package conventional water treatment plant which is approximately 32 years old. The plant was originally designed to meet a less stringent filter performance requirement than the current standard. It has several physical limitations including somewhat shallow media depth of approximately 38-inches as compared to modern standards, and an antiquated filter under drain system. The plant has a hydraulic flocculation system which is not as effective as current standard designs which use mechanical systems. While finished water turbidities have historically met all drinking water standards and generally indicate good filter performance, recent particle count data has indicated that the filters pass more particulate matter than is desirable. Operators have noted that the plant can be difficult to operate at times, including maintaining filter runs of more than eight hours (considered to be short by industry standards), and that backwash waste volumes are high compared to finished water production. In addition, operators have noted that it is difficult to remove the regulated amounts of naturally occurring organic matter from the raw water to maintain compliance with drinking water standards. The purpose of the project is to evaluate the existing system and develop an overall plan for a new water treatment facility. The planning included the following elements: Determine whether the existing facility is capable of meeting current and future regulations Identify recommended replacement or upgrade facilities for the existing plant and recommended construction schedule for a new facility Evaluate and document recommended treatment processes, including the pretreatment processes, filtration system, taste and odor treatment considerations, disinfection and chemical feed systems Evaluate facilities residuals handling and management Perform a rapid condition based assessment for the existing WTP building and structures to determine their expected life expectancy and capital investment needs over a 20 year period Identify alternative sites and develop preliminary layout configurations of a new or modified treatment facility, and perform a preliminary siting study Identify facility upgrades and develop a Capital Investment Plan for both the existing and/or new plant sites, so that capital investments for facilities can be planned Develop Opinions of Probable Cost for both Capital and O&M costs The raw water source for the water system is Bear Creek, with water being pumped to the Genesee Reservoir for storage prior to being treated at the District s Water Treatment Plant (WTP). Water quality conditions may deteriorate in the future as the Genesee Reservoir ages. In addition, raw water quality in Bear Creek may deteriorate as further upstream development occurs, or due to potential beetle kill of trees or forest fire. The performance of the existing treatment plant was analyzed and compared to requirements of both current and potential future drinking water regulations. It was determined that a more robust ES - 1 FINAL - June 2014

96 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District water treatment process would be required to reliably meet current and future water quality regulations during the 30 year planning horizon for the project. Six alternative treatment processes were identified that are capable of meeting Genesee s water treatment goals. A total Benefit Score was developed for each of the six treatment processes. The Net Present Value of the six treatment processes was also developed based on Capital costs and 20 years of O&M costs. Finally, a Benefit to Cost ratio was developed for each of the alternatives by dividing the Benefit Score by the Net Present Value. The highest ranking alternative is a treatment process that includes coagulation and flocculation followed by sedimentation, membrane filtration (either microfiltration or ultrafiltration), granular activated carbon (GAC) treatment and disinfection. The recommended treatment process was selected compared to alternatives based on the following factors: Had the highest Benefit score Had the highest Benefit to Cost ratio Was cost competitive compared to other options Positions the District well for potential future raw water quality challenges and changing regulations Is relatively simple and reliable to operate A process flow schematic for the recommend treatment process is shown in Figure ES-1. Chemicals are added to the raw water to improve solids removal. Water is then treated through the flocculation process, and then flows through plate settlers to remove particulates and the flocculated materials prior to the membrane system. The water is then filtered through microfiltration to remove remaining suspended material in the water. Following filtration, the water flows through GAC columns to further remove organic materials, taste and odor compounds and some micro-pollutants such as pharmaceuticals. The water is then disinfected with chlorine prior to distribution. The plant layout may include space for a future advanced oxidation process in order to provide higher levels of taste and odor compound and micropollutant treatment, or for ultraviolet (UV) disinfection. Two locations for the new water treatment facilities were considered including the existing Water Treatment Plant site, and the site of District s Wastewater Treatment Plant and Administration Building. An option that would split the new water treatment facilities between the two sites was also considered. The three options were evaluated considering cost, operational issues and institutional issues. The preferred alternative is to construct the new water treatment facilities at the site of the District s Wastewater Treatment Plant and Administration Building. The base Opinion of Probable Project Cost for the project is $6,040,000. This cost was developed without geotechnical information or detailed site survey. The Opinion of Probable Project Cost presented in this report is considered a Class 4 estimate by the American Association of Cost Engineers (AACE), with an expected accuracy of +20% to 10%. Applying the range, the Opinion of Probable Project Cost is $5,440,000 to $7,250,000. ES - 2 FINAL- June 2014

97 CHAPTER 1 INTRODUCTION Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District 1.1 PROJECT BACKGROUND The Genesee W&S District (Genesee) operates a package conventional water treatment plant which is approximately 32 years old. The plant was originally designed to meet a less stringent filter performance requirement than the current standard. It has several physical limitations including somewhat shallow media depth of approximately 38-inches as compared to modern standards, and an antiquated filter under drain system. The plant has a hydraulic flocculation system which is not as effective as current standard designs which use mechanical systems. While finished water turbidities have historically met all drinking water standards and generally indicate good filter performance, recent particle count data has indicated that the filters pass more particulate matter than is considered desirable. The District s operators have noted that the plant can be difficult to operate at times, that the plant has issues with achieving filter runs of more than eight hours, and that backwash waste volumes are high. In addition, removal of the the regulated amounts of naturally occurring organic matter in the raw water is difficult. The Genesee Water Treatment Plant Site Most package water treatment facilities are expected to have a useful life of approximately thirty years before the condition of tanks and equipment makes the replacement of the treatment facility more feasible and a better investment than upgrading the existing facility. Additionally, more stringent future drinking water quality standards may be a factor in determining whether the existing WTP should be renovated and upgraded, or replaced with a more robust treatment system. Typical triggers for upgrading or replacing water treatment facilities are shown in Figure 1-1. New Regulatory Requirements Concerns with System Reliability or Compliance Opportunities for Operational Savings or Improvement Decision to Upgrade or Replace Facility Equipment/ Structures Approaching End of Useful Life Changes in Raw Water Quality Deteriorating Treatment Performance Figure 1-1: Typical Triggers for Upgrading or Replacing Water Treatment Facilities 1 FINAL - June 2014

98 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District Implementation of significant upgrades to an existing system, or design and construction of a new facility, is a significant undertaking that typically requires several years to complete. The overall program includes planning, design, bidding, construction and finance planning. The planning of a new treatment facility may also impact other Capital Investment Planning (CIP) for current facilities. The Master Plan is intended to identify the path under which any new or upgraded treatment facilities will be implemented, the schedule for the improvements, and provide an Opinion of Probable Cost for the implementation. The purpose of the project is to evaluate the existing system and develop an overall plan for a new water treatment facility. The planning included the following elements: Determine whether the existing facility is capable of meeting current and future regulations Identify recommended replacement or upgrade facilities for the existing plant and recommended construction schedule for a new facility Evaluate and document recommended treatment processes, including the pretreatment processes, filtration system, taste and odor treatment considerations, disinfection and chemical feed systems Evaluate facilities residuals handling and management Perform a rapid condition based assessment for the existing WTP building and structures to determine their expected life expectancy and capital investment needs over a 20 year period Identify alternative sites and develop preliminary layout configurations of a new or modified treatment facility, and perform a preliminary siting study Identify facility upgrades and develop a Capital Investment Plan for both the existing and/or new plant sites, so that capital investments for facilities can be planned Develop Opinions of Probable Cost for both Capital and O&M costs The approach to completing the Master Plan was to conduct a series of workshops involving a Work Group consisting of two members of the Genesee Board of Directors, two members of Genesee management, and two members of the engineering firm Hatch Mott MacDonald (HMM). The Work Group reported to the full Genesee Board during the development of the project. 2 FINAL - June 2014

99 CHAPTER 2 DESCRIPTION OF WATER SYSTEM Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District 2.1 COMMUNITY DESCRIPTION AND POPULATION TRENDS Genesee is located in the foothills west of Denver, and southwest of Golden. Primary water uses include residential and commercial water use, as well as landscape irrigation. The Genesee water system serves a residential population of approximately 3,700 customers and approximately 30 commercial users. The Genesee service area stretches slightly north of the Interstate Highway 70 to Bear Creek on the south, and contains approximately 2,870 acres. Figure 2-1 shows the Genesee service area. Genesee s current service obligation is at over 98% build-out based on lot development. Using the Genesee Service Plan as a guide, 4,500 people are the expected maximum population served by the District. According to the Service Plan, Genesee is allowed to serve 1,542 residential units, 173 commercial units, and 33 other allocations. Actual development has varied somewhat from the original plan. As a result of Genesee s fast approach to buildout, no additional future growth was considered in this report. 2.2 WATER DEMANDS The Genesee service area is at 98% of Buildout Customers consist primarily of residential and commercial users, with both indoor and outdoor landscape irrigation uses. The outdoor water demand fluctuates with the irrigation season occurring between May and October. Historically, annual water use has ranged from 439 acrefeet in 2000 (including 40 acre-feet used to fill and refill a reservoir during construction) to 370 acre-feet in Water use in 2012 and 2013 averaged 400 acre-feet, or about 0.36 million gallons per day (mgd). Table 2-1 shows a summary of historical average and peak water demands. Demand Table 2-1: Genesee Historical Water Demands Million Gallons / Day Acre-feet / Month Historical Average Demands Winter Average Historical Peak Month Annual Average Day Historical Peak Demand Peak Day Demand 1.0 N/A 3 FINAL - June 2014

100 15 MILES TO DOWNTOWN DENVER EXISTING WWTP SITE EXISTING WTP SITE SCALE: 1"=4,000'

101 2.3 EXISTING WATER SUPPLY AND TREATMENT SYSTEM Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District Genesee s existing potable water supply system includes raw water conveyance and storage, treatment, and finished water transmission and distribution facilities. A schematic of the Genesee water system is shown in Figure 2-2. Raw Water Supply Sources The raw water supply source for Genesee consists of Bear Creek with a reservoir used to store water from Bear Creek. A water intake and pumping structure is located along Bear Creek and is used to pump water to the District s water treatment plant or to the District s 101 acre-foot reservoir that was constructed and placed in service approximately six years ago. Water can be supplied to the District s water treatment plant either from Bear Creek directly or from the reservoir. According to the District operators, the reservoir has served as the primary source of raw water supply since the time it was placed in service. Water Treatment Facilities Inlet and Raw Water Pumping facilities located along Bear Creek The Genesee water treatment facility is located along Highway 74 in the vicinity of Lair O the Bear open space, a few miles west of Idledale. The plant is a conventional water treatment facility that uses chemical addition, coagulation and flocculation, sedimentation, and filtration followed by chlorine disinfection. Figure 2-3 shows a schematic of the water treatment facilities. The water treatment processes consisting of the flocculation Package Filter Unit chambers, sedimentation basins and filters is a combined package system that was constructed during the early 1980s and is over 30 years in age. The treatment processes are discussed in further detail below. Coagulation and Flocculation. Most colloidal material in water (suspended solids that are small enough to pass through a conventional sand filter) has a negative surface electrochemical charge which prevents agglomeration of the particles and thus makes their removal from water difficult. Most pathogenic materials in water demonstrate similar negative surface charges. These materials are removed from water by adding a coagulant such as alum that acts to destabilize the negative surface charge of the particle thereby causing the colloidal material to become charge neutral. This allows the colloidal and pathogenic materials to agglomerate into larger particles. The water containing the charge neutral particles is then passed through a flocculation process which consists of multiple stages of gentle stirring causing these particles to collide and form larger solids. These solids become large enough to either be settled or filtered out of the water. Sedimentation. Sedimentation is used to remove a large percentage of the solids from the water, thereby improving subsequent filter performance and extending the filter run time before backwashing. The water treatment plant uses tube settlers to enhance the natural 4 FINAL - June 2014

102 FIGURE NO SCHEMATIC OF GENESEE POTABLE WATER SYSTEM GENESEE WATER TREATMENT FACILITIES MASTER PLAN

103 FIGURE NO GENESEE WATER TREATMENT PLANT PROCESS SCHEMATIC GENESEE WATER TREATMENT FACILITIES MASTER PLAN

104 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District settling process. The removed solids are washed from the sedimentation basin and discharged to the backwash pond. Filtration. Filtration provides a positive barrier for pathogenic organisms and other suspended solids remaining in the water following settling. Flocculated particles that do not settle out in the sedimentation process are strained out of the water in the filter. The filters have a media depth of approximately 38-inches (not including the underlying support layers), including a 26-inch thick layer of anthracite, and a 12-inch thick layer of sand. The 38 inches of media depth is within a typical range of filter media depths, but may be considered slightly shallow based on current requirements for performance. Disinfection and Finished Water Pumping. Following filtration water flows into the clearwell tank. The clearwell volume provides contact time for disinfection of the water. Gaseous chlorine is fed to disinfect the water and maintain a residual chlorine concentration in the distribution system in order to provide protection from pathogenic organisms. Following disinfection in the clearwell, water is pumped by a high-pressure pump station into the distribution system. Another important aspect of the facility is solids management. Solid materials from the sedimentation basin and backwash waste from the filters are discharged to the Backwash Pond, which is an open earthen basin. According to District operators, this Backwash Pond was intended to be a temporary facility at the time of construction but ultimately became the permanent structure. The Backwash Pond is not segmented and therefore a portion of it cannot be used for drying, nor can a segment of the pond be taken out of service for maintenance and cleaning. The Backwash Pond is located within the 100-year floodplain, making it vulnerable to damage and potential discharge to Bear Creek with significant storm events. The plant site has limited space available, making it unlikely that significant improvements to the system can be made. Decant water is pumped from this pond to the reservoir, and solids are typically removed annually from this pond by an outside contractor. Distribution System The Backwash Pond at the Genesee Water Treatment Plant site presents challenges for residuals management The Genesee water distribution system is relatively large with extensive piping, several pump stations, and two 600,000-gallon water storage tanks. Based on the size of the system and the volume of water storage, which is required to meet both operational and fire storage requirements, it is anticipated that water ages (time between treatment and use) in the distribution are relatively high. Treated water is introduced into the south side of the distribution system, and water ages are expected to be highest at the school site that is located north of Interstate I-70. The Crossings Pump Station. A series of pump stations are required to transmit treated water into the distribution system. 5 FINAL - June 2014

105 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District 2.4 CONDITION BASED ASSESSMENT OF EXISTING FACILITIES A Condition Based Assessment (CBA) of the existing water treatment facilities was performed as a key element of the Master Plan. The CBA addressed the plant s Inlet and Raw Water Pumping system, the WTP and the Base Pump Station located at the WTP site. The emphasis of the CBA was to determine the condition of the buildings and structures in order to determine their condition for possible future and continued use. The CBA was limited to visual observations of the condition of the facilities and a review of available drawings. The CBA describes HMM s observation of the condition, structural implications, possible repair solutions, and Budgetary Level Opinion of Probable Costs for these facilities. The condition of various equipment, piping and treatment processes was also reviewed, however since the existing equipment is not anticipated to be used in a future treatment facility, identified deficiencies with the equipment and facilities was simply listed for qualitative consideration in the Master Plan decision making process. Table 2-2 presents a summary of the improvements identified by the CBA. Table 2-2: Improvements Identified Through the CBA Budgetary Level Discussion Facility Opinion of Probable Cost for Repairs Inlet and Raw Water Pumping Facility $800 The improvements are relatively minor and are not considered a high priority Base Pump Station $7,400 These improvements are recommended since the facility will remain in service for the longterm; the renovation are considered to have a moderate priority Base Pump Station Headwall Significant renovations to the WTP block masonry and roofing are required if the facility will remain in long-term service $20,000 The headwall is located above the pump station in order to stabilize the cliff face; the renovation to this structure is considered a high priority 6 FINAL - June 2014

106 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District Budgetary Level Discussion Facility Opinion of Probable Cost for Repairs Water Treatment Plant $245,000 The building needs significant renovations if it is to remain in long-term service, in particular to the masonry and roofing systems. If the building will not remain in service for an extended time period, Genesee should determine the value of investing the renovation money. A minimum of $3,000 in renovations is recommended as a high priority to remove rust from and re-coat lintels, to protect the integrity of the building since it will remain in service for a minimum of several years until a new treatment facility could be constructed. A copy of the Technical Memorandum discussing the CBA can be found in Appendix A. 7 FINAL - June 2014

107 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District CHAPTER 3 WATER TREATMENT PROCESS SELECTION Implementation of significant upgrades to the existing system, or design and construction of all new facilities, is an important undertaking that requires careful study. Fundamental to the Master Plan is developing the recommended treatment process train that will serve the District for a 30- year planning horizon. 3.1 WATER TREATMENT PLANT CAPACITY The rated treatment capacity of the current water treatment facility is 1,400 gallons per minute (gpm), or 2.0 million gallons per day (mgd). However, the plant has consistently been operated at a maximum water production rate of 1,000 gpm (approximately 1.43 mgd) for many years. At a water production rate of 1,000 gpm, the plant is capable of producing enough water to meet water demands in about 8-10 hours during summer months, and in about 6 hours during winter months. The District s historical Peak Day Demand (PDD) is approximately 700 gpm. As previously noted, the District is currently at 98% of buildout, and therefore it is not anticipated that there will be significant increased water demands within the District in the future. The planned water treatment capacity of a treatment system can be impacted by a number of factors: Water demands within the District, with treatment capacity designed to meet at a minimum the Peak Day Demand Operational consideration, such as whether the plant will produce water over a 24-hr day, or only a portion of the day to match facility staffing times The amount of treated water storage in the system and diurnal water use patterns, in order to keep water storage tanks relatively full The capability of the transmission system (pump stations and pipelines) to move the plant s full production capacity into the distribution system; Genesee s transmission and pumping systems have the ability to move up to 1,500 gpm into the distribution system One significant consideration for the Genesee system is the potential for wild fires in the District, which would have a significant impact on the overall water system. Due to the potential for wild fires which would exert significant water demands on the system, a treatment capacity of 1,000 gpm (or 1.43 mgd) was selected for the future water treatment system, which exceeds the historical Peak Day Demand. This capacity will basically match the current operating capacity of the existing WTP. The Larkspur Pump Station along the transmission line. The transmission system is capable of moving 1,500 gpm into the Genesee distribution system. 8 FINAL - June 2014

108 3.2 GOALS FOR THE WATER TREATMENT PROCESSES Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District Goals for the water treatment processes include compliance with current and future regulations, as well as goals for operation performance and reliability. Regulatory Considerations There are several regulations that are important in evaluating the treatment processes for the Genesee WTP. These regulations include: Safe Drinking Water Act (SDWA) Surface Water Treatment Rule (SWTR) and Enhanced Surface Water Treatment Rule (ESWTR) Disinfection Byproduct Rule (DBPR) Enhanced Coagulation Treatment Technique/Rule These regulations and their significance are described in the following sections. Safe Drinking Water Act The Safe Drinking Water Act (SDWA) was originally passed by Congress in 1974 to protect public health by regulating the nation s public drinking water supply. The law was amended in 1986 and again in The SDWA authorizes the United States Environmental Protection Agency (USEPA) to set national health-based standards for drinking water to protect against both naturally occurring and man-made contaminants that may be found in drinking water and its sources including rivers, lakes, reservoirs, springs, and groundwater wells. In addition, drinking water that travels through an improperly maintained distribution system may also pose a health risk and standards have also been set to monitor the distribution system water quality. These standards are referred to as the National Primary Drinking Water Regulations (NPDWR.) The Primary Drinking Water Regulations set enforceable maximum contaminant levels for particular contaminants in drinking water along with required methods of treatment or removal. Each standard also includes requirements for water systems to test for contaminants in the water to ensure the standard was achieved. Water systems are required to treat the water, test their water frequently for the specified contaminants and report the results of the testing to the Colorado Department of Public Health and Environment (CDPHE.) The NPDWRs are divided into four categories: Inorganic Chemicals (includes metals, nitrite and nitrate, and asbestos) Organic Chemicals (includes over 50 synthetic organic chemicals, and limited disinfection by-products) Radionuclides (radiological contaminants) Microorganisms (includes turbidity, total coliforms, Legionella, viruses, Cryptosporidium and Giardia lamblia) Genesee has consistently maintained regulatory compliance with National Primary and Secondary Drinking Water Regulations. 9 FINAL - June 2014

109 Water Treatment Facilities Master Plan Report Genesee Water and Sanitation District In addition to the NPDWRs, the SDWA includes standards established through the National Secondary Drinking Water Regulations (NSDWRs). The NSDWRs are non-enforceable standards that regulate contaminants that may result in cosmetic deficiencies (such as skin or tooth discoloration) or aesthetic deficiencies (such as taste, odor, or color), but are not a threat to public health. The NSDWRs include standards for a series of inorganic chemicals, and other water quality parameters such as ph, color, odor, corrosivity, sulfates and total dissolved solids (TDS). Although non-enforceable, it is recommended that the requirements of the Secondary Standards be met in most circumstances. Genesee has maintained consistent regulatory compliance with the NPDWRs and the NSDWRs. Surface Water Treatment Rule and Enhanced Surface Water Treatment Rule The 1989 Surface Water Treatment Rule (SWTR) established treatment requirements for all public water systems using surface water or groundwater under the direct influence of surface water. Applicable requirements for the Genesee WTP include the following: Maintenance of a disinfection residual in water within the distribution system. Removal or inactivation of at least 99.9 percent (3-log) of Giardia and percent (4- log) of viruses. A combined filtered water turbidity limit of 5 NTU at any time and a limit of 1.0 NTU in 95 percent of measurements each month. These requirements were superseded by the 1998 Interim Enhanced Surface Water Treatment Rule (IESWTR) and the 2002 Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR). Systems covered by the LT1ESWTR, such as the Genesee, were required to comply with the regulation by January 14, The LT1ESWTR requires that public water systems that use surface water and serve fewer than 10,000 people, achieve 99-percent (2-log) removal of Cryptosporidium. This is in addition to the existing requirements of the SWTR for minimum removal requirements for Giardia and viruses. For filtered surface water systems the reductions are achieved by removal credits (physical removal through filtering) and inactivation credits (inactivation by disinfectants). It is assumed that if the new requirements for turbidity removal for combined filtered water are being met, then Cryptosporidium Giardia Lamblia cysts. A major emphasis of drinking water regulations is the removal and inactivation of pathogenic organisms such as Giardia. is being removed adequately (i.e. 2-log removal of Cryptosporidium.) Table 3-1 provides a summary of the maximum physical removal credits for viruses, Giardia and Cryptosporidium granted for various filtration treatment technologies. 10 FINAL - June 2014