TagPort Of Seattle(2611)

Technical memorandum dated September 5, 2000 from Elizabeth Leavitt (Port Of Seattle) to Ray Helwig (Washington State Department of Ecology), cc’d to Erik Stockdale, Nancy Groves (Ecology), Jim Kelley and Paul Fendt (Parametrix), Project No. 556-2912-001(03). Addresses CWA Section 401 permit issues for Seattle-Tacoma International Airport Master Plan Update projects involving wetlands and streams. Topics

A September 2000 report by Azous Environmental Sciences, commissioned by the Airport Communities Coalition, critically analyzes the Port of Seattle's wetland mitigation plan for the SeaTac Third Runway construction project. The report identifies numerous errors in wetland acreage accounting, inadequate mitigation ratios, and flaws in the proposed compensatory measures, including out-of-basin mitigation that fails to replace lost wetland functions in the affected Miller, Walker, and Des Moines Creek watersheds. The author concludes that the Port's plan falls short of Washington State Department of Ecology standards and the regulatory goal of no net loss of wetland functions.

Reinforced Earth Company (job number 8079, designer MJB, dated 09/01/00) design calculations for Port Of Seattle Sea-Tac International Airport, West Wall 181+25. Document covers internal and external stability analysis for a Mechanically Stabilized Earth (MSE) retaining wall structure including design parameters (select backfill φ=37°, γ=0.140 kcf, Ka=0.24858; random backfill φ=35°, γ=0.140 kcf, Ka=0.27269; foundation φ=35°,

This September 2000 preliminary design report, prepared by Kennedy/Jenks Consultants for the Port of Seattle, outlines a plan to augment water flow in Des Moines Creek near Seattle-Tacoma International Airport. The report covers facility configuration, process components such as backflow prevention, dechlorination, and aeration systems, as well as an evaluation of chemical dechlorination alternatives. The project was designed to improve creek water quality by treating and releasing water in a controlled manner.

A fisheries biologist assessed the Port of Seattle's plan to use City of Seattle drinking water to boost summer flows in Miller and Des Moines Creeks when levels drop below 1.0 cubic feet per second. The report concludes that chlorine and fluoride in drinking water are toxic to fish and other aquatic life at very low concentrations, and that mixing drinking water into these small streams would far exceed Washington State water quality standards even with dilution. The biologist recommended against the plan and suggested that treated well water from within the local watersheds might be a less harmful alternative.

A fisheries biologist, writing on behalf of the Airport Communities Coalition, assessed the Port of Seattle's plan to use City of Seattle drinking water to boost low summer flows in Miller and Des Moines Creeks near Sea-Tac Airport. The report concludes that the drinking water's chlorine and fluoride content would be highly toxic to fish and other aquatic life, far exceeding Washington State water quality standards even after dilution in the streams. The biologist recommends against the plan and suggests that well water from within the local watersheds may be a less harmful alternative.

Letter dated August 18, 2000 from Keith R. Smith, Water Resources Manager at Port Of Seattle (Seattle-Tacoma International Airport), to Jillian Hoyt of Seattle Public Utilities, regarding the Des Moines Creek Basin Plan Flow Augmentation Facility. The Port seeks to purchase water from SPU as an alternate supply for the proposed flow augmentation facility, which

In August 2000, the Port of Seattle submitted a revised implementation plan to the Washington Department of Ecology for a flow augmentation facility on Des Moines Creek, near Seattle-Tacoma International Airport. The plan outlines two potential water sources — a Port-owned well used to irrigate the Tyce Valley Golf Course, or water purchased from Seattle Public Utilities — along with details on pipeline construction, dechlorination treatment options, and pump configurations. Construction of the facility was scheduled to begin in June 2002, with the well preferred as the lower-cost option pending resolution of water rights issues.

A wetland scientist hired by the Airport Communities Coalition reviewed the Port of Seattle's proposed wetland mitigation plan for the SeaTac Third Runway construction and concluded it was wholly inadequate. The report argues that the planned out-of-basin mitigation at an Auburn site fails to replace the wetland functions lost in the Walker Creek, Des Moines Creek, and Miller Creek watersheds, and that placing mitigation in a different drainage basin cannot scientifically compensate for local losses under Washington State environmental law. The reviewer also warns that the Auburn mitigation site faces multiple risks and is unlikely to be sustainable long-term.

Memorandum from Brian Pippin (Parametrix, Inc.) to Linda Logan (cc: John Brooker), dated August 14, 2000, Project Number 556-2912-001, Port of Seattle WERs. Discusses critical conditions for Water Effect Ratio (WER) sampling per the Permit Writers Manual for the third runway treated stormwater discharge into Miller Creek. Uses HSPF hindcasting over 49-year period to evaluate