TagDes Moines Creek(162)

A 1998 internal memo from Parametrix, Inc. summarizes the results of a Reasonable Potential Analysis (RPA) conducted for the Seattle-Tacoma International Airport (STIA) Third Runway project, assessing whether stormwater runoff from the new runway could exceed water quality criteria in Miller Creek and Des Moines Creek. The analysis found that most pollutant concentrations after treatment with best management practices (BMPs) such as bioswales, sand filters, and wet ponds would meet criteria, with the exception of copper, which remained above acceptable levels. The memo also notes that existing pollutant concentrations in the receiving waterways during storms already exceeded criteria, even before accounting for Third Runway runoff.

In February 1998, the U.S. EPA Region 10 wrote to the Army Corps of Engineers recommending denial of a permit for the Port of Seattle's proposed third parallel runway at Seattle-Tacoma International Airport, citing concerns over the filling of more than 11 acres of wetlands and portions of Miller Creek and Des Moines Creek. The EPA objected that the applicant's mitigation plan relied almost entirely on off-site wetland replacement in the Green River Valley rather than within the affected watersheds, and questioned whether alternatives to wetland fills for the South Aviation Support Area and on-site borrow areas had been adequately explored. The agency indicated it was willing to work with the Corps and the Port to identify solutions that would satisfy both aviation safety needs and Clean Water Act Section 404(b)(1) requirements.

1997 Des Moines Creek Basin Plan, November 1997, prepared by the Des Moines Creek Basin Committee comprising City of SeaTac, City of Des Moines, Port of Seattle, and King County. Project technical team led by King County Department of Natural Resources, Water and Land Resources Division, with contributors including David Masters, David Hartley, Alan Johnson,

This June 1997 report, prepared by the Port of Seattle for Washington State's Department of Ecology, presents storm water receiving environment monitoring results conducted under NPDES Permit No. WA-002465-1. It covers water quality topics including instream toxicity bioassays, sediment quality, identification of pollution sources, metals speciation, vegetation management, and streambank erosion in Miller Creek and Des Moines Creek watersheds near Sea-Tac Airport. The findings assess the environmental impact of airport storm water runoff on local waterways and identify contributing pollution sources within each creek basin.

HNTB-prepared Final Draft Phase I study (November 1996) for Sea-Tac Airport Third Runway fill material alternative delivery methods. Evaluates transport corridors including Corridor 1 (Des Moines Creek barge transfer and land conveyor), Corridor 2 (SR 509 conveyor, truck, rail), and Corridor 3 (SR 518 conveyor, truck, rail). Covers technical viability, construction/environmental permitting (local, state, federal),

A 1993 letter from the Port of Seattle to a Des Moines resident explains that airline deicing at Sea-Tac Airport uses only FAA-approved ethylene or propylene glycol, and that wastewater from deicing drains to the airport's treatment system before being discharged to Puget Sound — not to Miller or Des Moines Creeks. The Port acknowledged its treatment plant was not designed to handle glycols and was evaluating upgrades. A follow-up 1996 letter challenges a contradictory statement in the airport's Final Environmental Impact Statement, which claimed most deicing fluids were contained and treated by the Port's Industrial Wastewater System.

A 1992 water quality study of Des Moines Creek, prepared by Parametrix, Inc. for the FAA and Port of Seattle, assessed the health of the creek during storm runoff events. The creek, which originates near Sea-Tac International Airport and flows to Puget Sound, had its aquatic ecosystem severely damaged by jet fuel spills in 1985 and 1986. The study sampled seven locations along the creek and three tributaries to identify water quality problems and determine whether stormwater pollution from airport operations was causing toxic conditions.