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EXH AR024622: Draft Memo — Site-Specific WQC Copper Status Update, Miller, Walker & Des Moines Creeks

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A February 2000 internal draft memorandum from environmental consultants to Port of Seattle staff summarizes efforts to develop a site-specific water quality criterion for copper in Miller, Walker, and Des Moines Creeks, in connection with stormwater runoff anticipated from a proposed third runway at Sea-Tac Airport. The memo evaluates two technical approaches—the Water-Effect Ratio (WER) and the site-specific metals translator—for potentially raising copper discharge permit limits, and outlines initial toxicity screening and range-finding study results. It also describes ongoing negotiations with the Washington State Department of Ecology regarding unresolved issues such as mixing zones, AKART requirements, and critical sampling conditions.

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Draft memorandum AR024622 dated February 14, 2000, from Doug Henderson and Linda Logan to Keith Smith (project number 556-2912-01), summarizing efforts to develop a site-specific water quality criterion (WQC) for copper in Miller Creek, Walker Creek, and Des Moines Creek in connection with Port Of Seattle third runway stormwater discharges (SDS-3). Document covers the Water-Effect Ratio (WER) and site-specific metals translator approaches, initial toxicity screening using Ceriodaphnia dubia (January 14, 1999), range-finding studies (February 23, 1999), and WER Workplan development (July 23, 1999). Discusses negotiations with Washington Department of Ecology (Gary Bailey), WAC 173-201A-100(2) AKART requirements, point of compliance for mixing zones, critical conditions per WAC 173-201A-020, Northwest Ponds, Lake Reba, and a parallel Parametrix project for City of Chehalis on copper, silver, and zinc in the Chehalis River. Filed in PCHB Third Runway EIS administrative record.

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