TagThird Runway(1067)

This October 1999 draft document outlines resolved and unresolved regulatory issues related to a Sea-Tac Airport expansion project, focusing primarily on stormwater management, wetland mitigation, and water quality concerns. Key unresolved issues include compliance with Ecology and King County Stormwater Manuals, the role of a proposed Regional Detention Facility (RDF) in wetlands, de-icing impacts on dissolved oxygen levels, and instream flow reductions in Des Moines Creek. Additional concerns involve NPDES permit compliance, clean fill criteria, legal proceedings before the Pollution Control Hearings Board, and whether a shoreline permit is needed for an Auburn mitigation site.

A October 1999 laboratory analysis report from Aquatic Research Incorporated details water sample testing conducted for Parametrix/Port of Seattle. One water sample collected on October 8-11, 1999 was tested for total suspended solids, petroleum hydrocarbons (diesel and motor oil), and total metals including cadmium, copper, lead, and zinc. Results showed low levels of contaminants, with zinc detected at 0.102 mg/l and copper at 0.0070 mg/l, while diesel and motor oil levels fell below detection limits.

In this October 1999 internal memo, Washington State Department of Ecology staffer Tom Luster describes a meeting with his supervisor Paula regarding the agency's water quality review of Sea-Tac Airport expansion. Luster explains that he cannot yet provide 'reasonable assurance' that the Port of Seattle's proposal will meet water quality standards for Des Moines Creek, citing inadequate stormwater treatment plans and the Port's removal of flow augmentation measures from its mitigation plan. He expresses concern that management pressure to approve the project quickly could compromise the integrity of the regulatory review process.

Hart Crowser memorandum from Michael Bailey, Allen Jones, and Doug Lindquist to Jim Thomson (HNTB), dated October 8, 1999, presenting probabilistic seismic hazard analysis (PSHA) results for the Sea-Tac Airport Third Runway project (J-4978-14). Reports peak horizontal acceleration (PHA) values for common design return intervals: 0.16 g (72-year), 0.36 g (475-year), 0.47 g (975-year), and

Hart Crowser subsurface conditions data report (project J-4978.02) prepared for HNTB and Port Of Seattle, dated September 24, 1999, covering Borrow Areas 1, 3, and 4 for the Sea-Tac Airport Third Runway project. Report includes generalized geologic conditions, subsurface soil conditions, hydrogeologic regime, groundwater elevation data, and perched water-bearing zone analysis. Field explorations used dual-wall

A September 20, 1999 internal memorandum from Parametrix, Inc. consultants to Scott Tobiason provides technical review comments on the first draft of the 1999 Annual Stormwater Report for Seattle-Tacoma International Airport (STIA). The memo raises concerns about consistency in water quality comparators, statistical methods for 'trimmed' data sets, and the attribution of reduced sediment levels to construction wheel wash versus other factors. It also flags regulatory issues regarding mixing zones, water quality standards language, and potential NPDES permit compliance implications of identifying pollution sources in the annual report.

Email chain from Raymond Hellwig (Washington State Department of Ecology) to Thomas Fitzsimmons and Bill Alkire, cc’ing Carol Jolly, Ron Langley, Tom Luster, Kevin Fitzpatrick, Dave Garland, Erik Stockdale, Roger Nye, and Paul David Carr, dated September 17, 1999. Discusses Governor’s reported commitment to Sea-Tac legislators (Paterson et al.) that the Section 401 Water Quality

A 1999 technical memorandum from Parametrix, Inc. to the Port of Seattle analyzes the sensitivity of stormwater discharge compliance determinations for Sea-Tac Airport's runways, focusing on dissolved copper concentrations in Des Moines Creek. The memo evaluates whether mixing zones and dilution factors could offset elevated copper levels in stormwater runoff, finding that ambient copper concentrations already exceeded water quality criteria in 37–65% of samples. The analysis concludes that dilution factors based on streamflow alone are unlikely to be significantly greater than 1.0, though accounting for the Northwest Ponds' reservoir volume raises the estimated dilution factor to approximately 1.7.

This draft memorandum from Parametrix (dated April 20, 1999) summarizes range-finding toxicity tests conducted as part of a water-effect ratio (WER) study examining copper levels in streams receiving stormwater runoff from Seattle-Tacoma International Airport (STIA). Water samples were collected from Miller Creek, Walker Creek, and Des Moines Creek during a storm event in February 1999 and tested using the organism Ceriodaphnia dubia to measure copper toxicity. Results showed water effect ratios ranging from 6.7 to 16.0, leading researchers to recommend pursuing a definitive WER study and a site-specific water quality standard for copper.