TagStormwater(385)

A February 2000 email from hydraulic consultant Bill Rozeboom argues that the proposed expansion of Sea-Tac Airport's Integrated Wetlands System (IWS) lagoon—tripling its storage capacity—is primarily driven by the airport's Master Plan Improvements, including the proposed third runway, rather than being a routine water quality project. Rozeboom notes that the planned increase in impervious drainage area (roughly 521 additional acres) closely mirrors the proposed increase in IWS storage volume, supporting his conclusion that the third runway is the primary driver of the expansion. He also raises concerns that the environmental documents fail to adequately assess the impact of large-scale out-of-basin water transfers on aquifer recharge and stream base flows in the Miller Creek and Des Moines Creek basins.

A February 2000 draft memorandum from environmental consultants to Keith Smith summarizes efforts to develop a site-specific water quality criterion for copper in Miller, Walker, and Des Moines Creeks near Seattle-Tacoma Airport, in anticipation of stormwater runoff from a proposed third runway. The memo outlines two technical approaches—the Water-Effect Ratio (WER) and the site-specific metals translator—for potentially raising copper discharge permit limits, and describes toxicity screening and range-finding studies conducted in 1999. The phased study approach was designed to avoid unnecessary costs if the WER method proved infeasible or if the Washington Department of Ecology would not permit its use in adjusting permit limits.

Email dated January 3, 2000 from Raymond Hellwig (WQ Program) to Tom Luster (SEA Program), cc’d to Ron Langley, Dave Garland, Erik Stockdale, Gordon White, Jeannie Summerhays, John Glynn, Kevin Fitzpatrick, Paula Ehlers, Megan White, and Dan Silver. Responds to Luster’s December 23, 1999 message regarding premature death of Coho salmon in Des Moines Creek

A January 2000 internal email from EPA's Raymond Hellwig to Tom Luster addresses concerns about premature deaths of Coho salmon in Des Moines Creek near Sea-Tac Airport, in the context of the proposed third runway project. The email clarifies that stormwater discharge regulation will be handled through NPDES permits rather than Section 401 Water Quality Certifications, as the NPDES permit provides the only mechanism for ongoing regulatory oversight under the Clean Water Act. Hellwig directs Luster to defer to the Water Quality Program on stormwater issues and to stop raising the 401 Certification as an alternative avenue for addressing water quality standards.

NMFS (National Marine Fisheries Service) Office of Counsel comments dated 12/17/99 on the Biological Assessment (BA) for Seattle-Tacoma International Airport Master Plan Update Improvements. AR 043243. Comments identify deficiencies in action area definition (50 CFR 402.02), matrix/checklist completeness, direct and indirect effects analysis, and cumulative effects regarding Puget Sound Chinook salmon critical habitat, Coho salmon,

A November 30, 1999 letter from Port of Seattle's Aviation Project Management Group to Seattle Public Utilities reports the fourth and final quarterly stormwater monitoring results for the Sea-Tac Airport North Employees' Parking Lot (NEPL). Testing of water samples collected throughout 1999 found pollutant levels—including metals, hydrocarbons, and suspended solids—well below Washington State residential water supply standards. Based on these results, the Port proposed ending the monitoring program and invited the City of Seattle to confer on whether further monitoring was warranted under their Interlocal Agreement.