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For questions about the Conveyence System Improvement Program, please contact Mark Buscher 

Wastewater Treatment Division
King Street Center
201 S. Jackson St., Suite 505
Seattle, WA 98104-3855

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Program Update, June 2007

CSI Program Update Cover, June 2007
View table of contents

This regional Conveyance System Improvement Program Update implements conveyance policies contained in the Regional Wastewater Services Plan (RWSP), adopted by the King County Council in 1999. The update identifies projects needed for increasing capacity in the conveyance system to accommodate population growth; and, also provides a status on the County's asset management program for replacing or substantially rehabilitating deteriorated portions of the system. It then lays out a schedule and budget for these projects.

The intent is to develop current and projected peak flows to all facilities in the King County conveyance system and analyze the conveyance capacity for each facility (pipeline, pump station, and storage facility) and then compare the current and projected peak flows to the conveyance capacity of the existing facilities to assess the timing of additional capacity needs (Appendix A). Each projected improvement project is described in the project dscription summary (Appendix B). The CSI Program Update focuses on the separated portion of the system and is based on an identification of projected capacity shortfalls contained in the Regional Conveyance System Needs document (Appendix C).

Component (local) sewer agencies were instrumental in helping to identify conveyance needs, and prioritize projects through their participation on MWPAAC's Engineering and Planning (E&P) Subcommittee and through one-on-one meetings with Wastewater Treatment Division staff.

View the Executive Summary and Table of Contents.

Key Points for the CSI Program Update

Adoption of the RWSP in 1999 established a uniform design standard for the regional conveyance system. The standard is intended to avoid sanitary sewer overflows by establishing a 20-year peak flow standard system-wide.

Prior to RWSP adoption, the region had no uniform design standard for conveyance facilities. Consequently, half of the planned projects identified in this Conveyance System Improvement Program Update address capacity needs where flow monitoring and modeling data indicate that the 20-year peak flow cannot currently be conveyed.