TagStormwater(385)

A technical review by Northwest Hydraulic Consultants, submitted to the U.S. Army Corps of Engineers and Washington State Department of Ecology in May 2000, raises serious concerns about the stormwater management plan for Seattle-Tacoma International Airport's proposed third runway. The report identifies major flaws in the hydrologic modeling used to assess drainage impacts, including inconsistent soil-type assumptions and unreliable flow predictions for Miller Creek. The consultants call for a complete overhaul of the modeling process, independent technical review, and clearer regulatory oversight of the Port of Seattle's stormwater design work.

Final report prepared by Scott Tobiason, Aviation Environmental Programs, Port Of Seattle, documenting Stormwater Whole Effluent Toxicity (WET) testing at Seattle-Tacoma International Airport (STIA), May 2000. AR 044473. Covers WET testing background, sampling methods, STIA storm drainage subbasins, source-tracing of SDN1 outfall, chelation testing, synthetic runoff WET test results, field investigations, and NPDES stormwater discharge

A draft memorandum dated April 2000 summarizes range-finding water-effect ratio (WER) toxicity tests conducted for the Port of Seattle to measure copper levels in streams receiving stormwater runoff from Seattle-Tacoma International Airport (STIA). Water samples were collected from five sites — including Miller Creek and Des Moines Creek — during a storm event on April 15, 2000, and tested using Daphnia magna organisms to compare copper toxicity in site water versus clean laboratory water. The results were intended to determine whether more expensive definitive WER studies would be warranted, and to help establish site-specific water quality standards for copper.

This April 2000 draft memorandum from the Port of Seattle summarizes range-finding toxicity tests conducted to evaluate water-effect ratios (WERs) for copper in streams receiving stormwater runoff from Seattle-Tacoma International Airport (STIA). Water samples were collected from five sites—including Miller Creek and Des Moines Creek—during a storm event on April 15, 2000, and tested using Daphnia magna to measure how site water chemistry affects copper toxicity compared to clean laboratory water. The results were intended to help determine whether full definitive WER studies were warranted, which could support the establishment of site-specific water quality standards for copper in receiving streams.

In an April 2000 email, Port of Seattle executive Gina Marie Lindsey updates a Washington State Department of Ecology contact about the status of the Port's stormwater permit application related to a Comprehensive Stormwater Master Plan. She explains that while the environmental work quality was deemed strong, the submittal needed to be reformatted to meet King County's review standards rather than DOE's, with a revised package due May 5 and a County final review expected by mid-June. Lindsey also addresses concerns about potential 'piecemealing' of the permit process and expresses concern about the lengthy timeline given the County reviewer's limited weekly hours for the project.

Handwritten notes from a BEATAC meeting at the Port on April 20, 2000, AR018447, involving City of Des Moines personnel including Tom Walsh, Tacie Borden, John Marchiloro, Jim Kelly, and others. Topics include: stormwater review at FCC starting 5-5-00; SR-509 temporary interchange issues (ESA/BA review, Jonathan Freedman indirect impacts, erosion/sediment control, no federal nexus); LWS#3

Draft memorandum dated April 20, 2000, authored by Doug Henderson and Linda Logan (job number 556-2912-001) for Port of Seattle project files, summarizing range-finding water-effect ratio (WER) toxicity tests for copper in streams receiving Seattle-Tacoma International Airport (STIA) stormwater. Tests used Daphnia magna as indicator species; copper was spiked into site water and synthetic laboratory

A April 2000 email exchange between EPA staff members John Savich and Martha Choe provides an update on the status of a Clean Water Act Section 401 water quality permit for a Port of Seattle runway project. The main sticking point is stormwater storage management, with the Washington State Department of Ecology (DOE) targeting a mid-July decision after King County completed a review that identified serious shortcomings in the port's consultant work. Both the optimistic and realistic port timelines require DOE action on the 401 permit by July 21, meaning the port had already abandoned any hope of beginning construction that season.

A April 2000 memo from engineering firm Parametrix, Inc. evaluates roofing options to prevent zinc leaching from galvanized steel roofs on two Port of Seattle warehouses at Sea-Tac Airport. The study compared paint systems (ranging from $21,000–$240,000 for both buildings) against synthetic coverings such as spray-on elastomers and single-ply membranes ($60,000–$330,000), finding that painting is cheaper but requires more frequent maintenance while synthetic coverings last longer but cost more upfront. The memo recommends that any chosen material be evaluated to ensure it does not release metals or other pollutants into stormwater runoff.

A February 2000 draft memo from environmental consultants Parametrix summarizes testing and monitoring data concluding that stormwater runoff from Seattle-Tacoma International Airport (STIA) does not harm aquatic life in nearby Miller and Des Moines Creeks. Three lines of evidence are presented: whole effluent toxicity tests showing most outfalls are non-toxic, water effect ratio studies demonstrating that creek water significantly reduces copper toxicity, and metals monitoring confirming that copper concentrations in the creeks fell below water quality standards. The one outfall found to be toxic (SDN1) was traced to zinc leaching from galvanized rooftops, with the Port of Seattle pursuing corrective measures.