WTD Recommended CSO Control Plan

Read the letter to the community from the Wastewater Treatment Division Director and October 17 news release.

Recently, King County’s Wastewater Treatment Division worked with leaders and community members to develop a recommended update to our CSO control plan. We invite you to continue the discussion and help shape the proposal that King County Executive Dow Constantine will forward to the King County Council next spring.

2011 Summary of Technical Documents, November 2011 (27MB)
The 2011 Summary of Technical Memorandums (Summary of TMs) is a companion to the King County 2011 Wastewater Treatment Division (WTD) Recommended Combined Sewer Overflow (CSO) Control Plan. This Summary of TMs documents King County’s review of its CSO Control Program, which was conducted in accordance with policies and guidelines in the 1999 Regional Wastewater Services Plan (RWSP). It is supported by eight technical memorandums (below).

These were developed to solicit public and agency comment to inform the future 2012 Executive’s Preferred CSO Control Plan and 2012 CSO Control Program Review Report. Together these will recommend changes to the County’s Long-term CSO Control Plan (Plan) and will be submitted to the King County Council and the public in the spring of 2012. Resulting adopted changes to the Plan will be incorporated into the 2012 Long-term CSO Control Plan Amendment to be submitted to the Washington State Department of Ecology (Ecology) and the United States Environmental Protection Agency (EPA) in fall of 2012. This process is presented below.

Now posted:

• TM 750, Sediment Deposition and Contamination Potential from Treated CSO Discharges, January 2012 (1MB)
• Public and Regulatory Agency Participation Plan, December 2011 (0.2MB)

The following technical memorandums (TMs) are referenced in the WTD Recommended CSO Control Plan.

• TM: Habitat Project Opportunities, August 2010 (3MB)
• TM 540: Evironmental and Habitat Priorities, November 2010 (0.7MB)
• TM 620: Cost Estimating Methodology for CSO Control Facilities, May 2011 (1MB)
• TM 700: Treatment Technology Selection, June 2011 (O.7MB)
• TM 810: Green Stormwater Infrastructure Feasibility Evaluation, October 2011 (29MB)
• See also: green stormwater infrastructure for combined sewer overflow control  
• TM 970: CSO Control Alternatives Development, October 2011
• Report (3MB)
• Appendices (108MB)
• Detailed contents
• Appendix A. Alternatives Summary (2.6MB)
• Appendix B: Hydraulic Modeling Update and Evaluations (2.7MB)
• Appendix C: Green Stormwater Infrastructure Feasibility (See TM 810)
• Appendix D: Screening Criteria (0.8MB)
• Appendix E: Preliminary Alternative Screening Results (8.7MB)
• Appendix F: Planning-Level Sizing Assumptions (1.7MB)
• Appendix G: Final Alternative Documentation (91.6MB)
• Appendix G.1: Ship Canal—11th Ave NW, 3rd Ave W, University, and Montlake (25MB)
• Appendix G.2: (Not Used)
• Appendix G.3: Middle EBI—Hanford #2, Lander St, Kingdome, and King St (23MB)
• Appendix G.4: Middle EBI—Hanford #1 (13MB)
• Appendix G.5: South EBI—S Michigan St and Brandon St (18MB)
• Appendix G.6: West Duwamish—W Michigan St and Terminal 115 (9MB)
• Appendix G.7: West Duwamish—Chelan Ave (15MB)
• Appendix H: Triple-Bottom-Line Analysis—Screening of Final Alternatives (2MB)
• Appendix I: Evaluations for Dexter Ave CSO Site (2MB)
• TM 1100: Project Sequence, October 2011 (0.4MB)