TagPort Of Seattle(2611)

Internal email from Tom Luster (Ecology) to Raymond Hellwig, Kevin Fitzpatrick, Erik Stockdale, and Paula Ehlers, dated September 16, 1999, regarding SeaTac Airport 401 certification and compliance with water quality standards under the Clean Water Act. Discusses non-attainment of water quality standards in Des Moines Creek and Miller Creek, antidegradation requirements, Level 2 detention requirements,

Internal email from Tom Luster (Washington State Department of Ecology) to Raymond Hellwig, Kevin Fitzpatrick, Erik Stockdale, and Paula Ehlers dated September 16, 1999, outlining unresolved stormwater issues in the 401/CZM review of Port Of Seattle’s Sea-Tac Airport Master Plan Expansion. Topics include: definitions of ‘modified Level 1’ and ‘Level 2-type flow control’; role of

A 1999 technical memorandum from Parametrix, Inc. analyzes whether stormwater discharged near Des Moines Creek meets Washington State dissolved copper water quality criteria, using a Monte Carlo simulation model. The analysis finds that copper levels in the stormwater effluent consistently exceed water quality standards regardless of background ambient concentrations, with dilution factors generally less than 2. The study evaluates several potential remedies, including increased onsite detention, expanded mixing zones, and water effect ratio adjustments, finding that the Water Effect Ratio (WER) is the most influential factor in achieving compliance.

Annual Stormwater Monitoring Report for Seattle-Tacoma International Airport (Sea-Tac Airport) covering July 1, 1998 through June 30, 1999, prepared by Port Of Seattle, September 1999 (AR 026459–AR 026461). Includes stormwater quality data tables for outfalls SDE4, SDS3, SDN1, and SDN4 with copper (CAS No. 7440-50-8) concentration measurements in micrograms per liter, hardness-dependent freshwater acute water

This is the Annual Stormwater Monitoring Report for Seattle-Tacoma International Airport, covering the period from July 1, 1998 through June 30, 1999, prepared by the Port of Seattle. The report documents water quality sampling results from airport storm drainage systems, including measurements of petroleum hydrocarbons, metals, fecal coliforms, and the effects of aircraft and ground deicing activities on runoff. It includes data summaries, outfall inspections, and source tracing studies aimed at tracking and managing stormwater pollution from airport operations.

Annual Stormwater Monitoring Report for Seattle-Tacoma International Airport (STIA) covering the period July 1, 1998 through June 30, 1999, prepared by Port Of Seattle, September 1999. Report AR 042872 covers NPDES stormwater sampling at STIA storm drainage subbasins including grab and composite sample results for total petroleum hydrocarbons (TPH), fecal coliforms, suspended solids (TSS), turbidity,

Annual stormwater monitoring report (AR018047) prepared by Port Of Seattle for Seattle-Tacoma International Airport (STIA) covering the period July 1, 1998 through June 30, 1999. Documents NPDES stormwater sampling results across STIA storm drainage subbasins including grab and composite samples for total petroleum hydrocarbons (TPH), fecal coliforms, suspended solids (TSS), turbidity, biochemical oxygen demand (BOD5),

This 1999 internal memo from the Washington State Department of Ecology details the history of environmental cleanup oversight at Seattle-Tacoma International Airport, where 15 separate contaminated sites involving jet fuel and gasoline were managed individually under the state's Model Toxics Control Act. The memo describes a series of prepaid staff positions funded by the Port of Seattle to coordinate cleanup efforts with airline and pipeline companies, and the challenges in getting formal Agreed Orders signed. It concludes with an update that a key groundwater study Agreed Order was finally signed in May 1999 after receiving over 600 public comments in opposition.

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.