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2023.05.18 Board Agenda Attachment RWSPRecycled Water Strategic Plan Update May 18, 2023 Stephen Caswell, Principal Engineer Elisa Garvey, Carollo Engineers 1 2 Introduction and Background 2 District Recycled Water Strategic Plan Objectives 3 Develop a long-term strategy for District wastewater effluent disposal/reuse that incorporates viable alternatives to the existing system. These alternatives would be triggered for implementation by existing or future drivers and/or constraints. 50 Year Planning Horizon KEY POINTS Brief recap: Strategic plan is a 50-year vision Objective – Message is in blue box on slide Roadmap 3 Recycled Water Strategic Plan Development 4 SAG = Stakeholder Advisory Group We are here Most viable alternatives moving forward to detailed evaluation 4 Existing System Challenges KEY POINTS Brief recap: Important to consider in a 50 year horizon Provide some highlights of the challenging aspects of the existing system Energy costs Investment in export infrastructure Alpine county litigation Rancher agreements 5 6 Alternatives Identification and Screening 6 Alternatives Identification and Screening Brainstorming exercise Wide net of potential options Identify most viable options for detailed evaluation 7 1,2,3 6 4 12,13,14 7 5 9 11 District WWTP End Use Location of Alternative Lake Tahoe Basin Truckee River Watershed Upper Carson Watershed 15,16 10 WWTP = wastewater treatment plant 8 South Fork American River Watershed KEY POINTS Overview of alternatives generation process: Alternatives list developed through team brainstorming exercise Wide range of options Varying challenges and benefits Shown on map – purple dots represent end use location 4 different regions Upper Carson watershed - CA and NV Truckee watershed South Fork American watershed Lake Tahoe basin 7 8 Alternatives Identification and Screening Truckee River Watershed 8 Truckee River Watershed Alternatives 9 9 District WWTP End Use Location of Alternative Lake Tahoe Basin Truckee River Watershed Upper Carson Watershed WWTP = wastewater treatment plant Conveyance to TTSA for subsurface discharge to Truckee River South Fork American River Watershed KEY POINTS Overview of alternatives generation process: Alternatives list developed through team brainstorming exercise Wide range of options Varying challenges and benefits Shown on map – purple dots represent end use location 3 different regions Upper Carson watershed - CA and NV Truckee watershed Lake Tahoe basin 9 Key Challenges Infrastructure and Treatment 15-mile transmission pipeline from District WWTP to TCPUD System Significant challenges with pipeline construction Potential environmental impacts TCPUD and TTSA are capacity limited 10 11 Alternatives Identification and Screening South Fork American River Watershed 11 South Fork American Watershed Alternatives Discharge to the American River Non-potable recycled water use in American River Watershed Snowmaking Irrigation District WWTP End Use Location of Alternative Truckee River Watershed Upper Carson Watershed WWTP = wastewater treatment plant 8 South Fork American River Watershed KEY POINTS Overview of alternatives generation process: Alternatives list developed through team brainstorming exercise Wide range of options Varying challenges and benefits Shown on map – purple dots represent end use location 3 different regions Upper Carson watershed - CA and NV Truckee watershed Lake Tahoe basin 12 Key Challenges Infrastructure and Treatment 28-mile pipeline Significant technical challenges Potential for environmental impacts Treatment upgrades for discharge to South Fork American River Filtration and nutrient removal Treatment upgrades for non-potable recycled water use Filtration and disinfection 13 14 Alternatives Identification and Screening Lake Tahoe Basin 14 Lake Tahoe Basin Alternatives Land Application Discharge to waterways Potable Reuse Indirect Potable Reuse Direct Potable Reuse 12,13,14 11 District WWTP End Use Location of Alternative Lake Tahoe Basin 15,16 10 WWTP = wastewater treatment plant Truckee River Watershed Upper Carson Watershed South Fork American River Watershed 15 Key Challenges 16 Alternatives – Discharge to Tributaries or Land Application of recycled water Outstanding National Resource Waters (ONRW) designation of Lake Tahoe Applicable to: Lake Tahoe Tributaries Potentially applicable to land application of recycled water (irrigation or snowmaking) 17 Treatment Requirements Total dissolved solids and chloride removal Reverse Osmosis (RO) is industry standard process Nutrient removal Limits of technology for biological nutrient removal = 3 mg/L TN Reverse Osmosis (RO) required to further reduce TN TN objective may not be achievable Trace organics removal Ultraviolet disinfection and advanced oxidation (UV/AOP) Requires TDS and chloride removal Requires nutrient removal Treatment Train Nutrient Removal + MF+ RO + UV/AOP 18 WWTP Planning Level Cost Estimates WWTP Energy Demand Comparison 19 Additional Considerations – RO Brine Disposal RO brine disposal Estimated volume based on partial treatment = 250,800 gal per day Disposal Landfill – Approximately 30 trips per day Deep well injection – requires isolated groundwater basin Thermal concentration and crystallization Energy intensive 1.5 Millions of kWh Industrial process 20 Potable Reuse Alternatives Environmental buffer with travel/residence time that meets or exceeds minimum requirements Environmental buffer with travel/residence time that does not meet minimum requirements No environmental buffer. Added to source water to water treatment plans No environmental buffer. Added water distribution system 21 Potable Reuse Alternatives Injection only viable approach Potable reuse via injection requires MF + RO + UV/AOP Allowance to demonstrate equivalent treatment train (non-RO) Meeting groundwater quality objectives requires RO and possibly nutrient removal Regulations expected end 2023 Anticipated required treatment train includes RO No anticipated allowance to demonstrate equivalent treatment train (non-RO) 22 WWTP Planning Level Cost Estimates WWTP Energy Demand Comparison 23 Lake Tahoe Basin Alternatives Land Application Discharge to waterways Potable Reuse Indirect Potable Reuse Direct Potable Reuse 12,13,14 11 District WWTP End Use Location of Alternative Lake Tahoe Basin 15,16 10 WWTP = wastewater treatment plant Truckee River Watershed Upper Carson Watershed South Fork American River Watershed KEY POINTS We’ve identified challenges: Legislative Regulatory Technological Cost Energy And we’ve identified what is needed for these alternatives to be more viable, When it comes to viability of the in basin options, we have other options that are more viable overall. 24 25 Alternatives Identification and Screening Carson River Watershed 25 Carson River Watershed Alternatives 1,2,3 6 4 7 5 District WWTP End Use Location of Alternative Truckee River Watershed Upper Carson Watershed WWTP = wastewater treatment plant South Fork American River Watershed Existing System Expansion of non-potable recycled water use in Alpine County Treatment upgrades and expansion of non-potable recycled water use in NV KEY POINTS Removes the challenges of Porter Cologne, ONRW, Settlement Act, TRPA 26 Key Challenges 27 Advanced Disinfected Secondary Treatment Export Pipeline Harvey Place Reservoir District Irrigation Rancher Irrigation Existing System Export Pipeline Harvey Place Reservoir District Irrigation Rancher Irrigation Expanded Disinfected Secondary Effluent Reuse Disinfected Tertiary Treatment Export Pipeline Harvey Place Reservoir District Irrigation Rancher Irrigation Expanded Disinfected Tertiary Effluent Reuse Advanced Disinfected Secondary Treatment Landscape Irrigation 28 Export Pipeline Harvey Place Reservoir Pastureland Irrigation Expanded Class A or B Reuse in NV Treatment to Meet Class A or B Reuse in NV* Landscape Irrigation Conveyance Pipeline or Indian Creek CA NV Pipeline to DCLTSA DCLTSA Export Pump Station Pastureland Irrigation Conveyance to DCLTSA Tertiary Treatment Nutrient Removal DCLTSA Export Pipeline CA NV Alfalfa Irrigation Tertiary Treatment Nutrient Removal Reverse Osmosis Export Pipeline Harvey Place Reservoir Discharge to West Fork Carson River West Fork Carson 29 Recycled Water Strategic Plan Next Steps 30 SAG = Stakeholder Advisory Group We are here 30 31 Questions? 31