Regional Wastewater Services Plan (RWSP) 2013 Comprehensive Review June 2014 King Street Center, KSC-NR-0512 201 South Jackson Street Seattle, WA 98104 http://dnr.metrokc.gov/wtd/ For comments or questions, contact: Pam Elardo, P.E., Division Director King County Wastewater Treatment Division 201 South Jackson Street KSC-NR-0512 Seattle, WA 98104-3856 206-477-4530 [email protected] This information is available in alternative formats on request at 206-477-5371 (voice) or 711 (TTY) Contents Executive Summary .................................................................................................................................. ES-1 Chapter 1 Introduction .............................................................................................................................. 1-1 King County’s Wastewater Treatment System ...................................................................................... 1-2 Regional Wastewater Services Plan ....................................................................................................... 1-4 Chapter 2 RWSP Achievements in 2007−2013 .......................................................................................... 2-1 RWSP Policies Implementation .............................................................................................................. 2-1 RWSP Capital Projects ............................................................................................................................ 2-2 Brightwater Treatment System .......................................................................................................... 2-3 Carnation Treatment Plant ................................................................................................................ 2-4 Conveyance System Improvement Projects ...................................................................................... 2-5 Reducing Infiltration and Inflow ........................................................................................................ 2-8 Protecting Our Waters Program ........................................................................................................ 2-9 Implementing the Sediment Management Plan .................................................................................. 2-14 Cleaning Up the Lower Duwamish Waterway Superfund Site ............................................................ 2-14 Creating Resources from Wastewater ................................................................................................. 2-15 Biosolids Recycling Program ............................................................................................................ 2-15 Energy Recovery and Efficiency Program ........................................................................................ 2-17 Reclaimed Water Program ............................................................................................................... 2-18 Protecting our Assets ........................................................................................................................... 2-20 Chapter 3 Financial Stewardship ............................................................................................................... 3-1 Establishing Annual Sewer Rate and Capacity Charge ........................................................................... 3-1 Residential Customer Equivalents ..................................................................................................... 3-2 Sewer Rate and Capacity Charge Projections .................................................................................... 3-4 Continuous Improvement Programs ..................................................................................................... 3-7 Productivity Initiative Pilot Program .................................................................................................. 3-7 Bright Ideas Program ......................................................................................................................... 3-8 Policy Guidance on Construction Fund and Emergency Reserves ......................................................... 3-8 Chapter 4 Forecasting Future Wastewater Treatment Plant Capacity Needs ........................................... 4-1 Summary ................................................................................................................................................ 4-1 Methodology .......................................................................................................................................... 4-2 Planning Assumptions ............................................................................................................................ 4-2 RWSP 2013 Comprehensive Review i Contents Population and Employment Forecasts ................................................................................................. 4-4 Average Wet Weather Flow Forecasts .................................................................................................. 4-7 Estimating Flow Factors for the Baseline Year ................................................................................... 4-7 Forecasting Future Flows ................................................................................................................... 4-8 Wasteload Forecasts ............................................................................................................................ 4-10 Estimating Loading Factors for the Baseline Year ............................................................................ 4-10 Forecasting Future Loadings ............................................................................................................ 4-10 Comparison of Future Flows, Loadings, and Capacities....................................................................... 4-12 Implications for Future Planning .......................................................................................................... 4-16 Chapter 5 Preparing for the Future ........................................................................................................... 5-1 Climate Change ...................................................................................................................................... 5-1 Regulatory Environment ........................................................................................................................ 5-2 Nutrient Removal ............................................................................................................................... 5-2 Source Control ................................................................................................................................... 5-3 Chemicals of Concern......................................................................................................................... 5-3 Other Topics ....................................................................................................................................... 5-3 Technology Trends ................................................................................................................................. 5-3 Decentralized Wastewater Systems .................................................................................................. 5-4 Nutrient Recovery .............................................................................................................................. 5-4 Energy Recovery ................................................................................................................................. 5-5 Indirect and Direct Potable Reuse ..................................................................................................... 5-5 Building Equity and Opportunity ........................................................................................................... 5-6 Chapter 6 Conclusions and Next Steps ...................................................................................................... 6-1 Conclusions ............................................................................................................................................ 6-1 Next Steps .............................................................................................................................................. 6-2 Appendix A. RWSP Policies Implementation in 2007−2013…………………………………………………………………A-1 Appendix B. Odor Prevention and Control Program……………………………………………………………………………B-1 Appendix C. Water Quality and Sediment Monitoring in 2013……………………………………………………………C-1 ii RWSP 2013 Comprehensive Review Contents Tables Table 3-1. Residential Customer Equivalents (1994–2013) ....................................................................... 3-3 Table 3-2. WTD Capacity Charge (2003−2014) .......................................................................................... 3-7 Table 4-1. Previous and Updated Planning Assumptions .......................................................................... 4-3 Table 4-2. Per-capita and Employee Flow Factors for 2010 ...................................................................... 4-8 Figures Figure 1-1. King County Wastewater Service Area and Facilities .............................................................. 1-3 Figure 1-2. Regional Wastewater Services Plan Projects and Service Areas (1999-2030) ........................ 1-5