TagThird Runway(1068)

A July 2001 email from King County engineer Kelly Whiting summarizes ecological recommendations regarding proposed stream flow mitigation measures. A lead stream ecologist advised that mitigation plans be compared against existing stream hydrology to avoid abrupt changes that could disrupt biological processes, such as sudden summer flow increases confusing fish behavior. The ecologist also emphasized that water quality factors like temperature and dissolved oxygen are as important as flow rates, and suggested introducing reserved water gradually through ponds or wetlands rather than directly into streams.

This table from a July 2001 Comprehensive Stormwater Management Plan summarizes drainage area measurements and changes in impervious surfaces (such as pavement and rooftops) across Miller Creek, Walker Creek, and Des Moines Creek watersheds at Seattle-Tacoma International Airport (STIA). It compares 1994 baseline conditions to projected 2006 future conditions, showing a total increase of approximately 305.7 acres of impervious area across all drainage basins. The data was compiled from GIS coverage to support stormwater management planning for the airport's master plan update.

This section of Sea-Tac International Airport's Comprehensive Stormwater Management Plan outlines proposed Master Plan Update (MPU) improvements and their likely stormwater management requirements. It describes how land use changes — including increases in impervious surfaces across various airport development phases — were analyzed using GIS and hydrologic modeling to assess drainage impacts. The document also notes that projects such as the relocated Airport Surveillance Radar required specific flow controls to manage stormwater runoff on the west side acquisition area.

This document is Table A-3 from the Sea-Tac Airport Master Plan Update, outlining construction projects that require stormwater management. It details activities such as runway safety improvements, taxiway construction, terminal expansions, and embankment work, noting for each whether permanent stormwater detention was provided, the construction timeline, and the type of drainage facility used. Projects are categorized as either new or retrofit stormwater installations, with comments describing impervious surface impacts and drainage routing to temporary or permanent detention facilities.

This document describes the Integrated Water System (IWS) stormwater management configuration at Seattle-Tacoma International Airport (Sea-Tac), detailing storage lagoons totaling 76.9 million gallons and a treatment rate of 4.0 million gallons per day across approximately 435 acres. Simulations over a 50-year period confirmed zero overflow events under proposed conditions, with overflows only beginning to occur if treatment rates dropped below 3.1 million gallons per day. The system experienced only one historical overflow during an extreme rain-on-snow event in December 1996–January 1997, with no petroleum hydrocarbons detected downstream.

STIA construction site stormwater monitoring report dated 6/28/01, sampled by K. Ludwa and J. Brandt. Documents monitoring of multiple construction sites including Third Runway Embankment Phase 4, S. 160th St. Detention Ponds, S. 157th Pl. Detention Pond, North Safety Fill Construction, Third Runway Embankment Phase 3, North Runway Embankment Phase 3, Wetland 44a, Lonistic Site

STIA construction site stormwater monitoring log dated 6/28/2001, samplers K. Ludwa and J. Brandt. Documents field observations for Phase 3 Embankment Construction, ASR Relocation, and Third Runway Project Office and Parking areas near Lowe Blvd & 12th Ave S, 8th Ave S, Miller Creek, SR509, Wilson Rd, and 12th Ave S. Records pH, turbidity, sheen

The Port of Seattle recorded this Declaration of Restrictive Covenants to permanently protect the Tyee Valley Golf Course Mitigation Area as a natural wetland, as required by the Washington State Department of Ecology and the U.S. Army Corps of Engineers in connection with the construction of Sea-Tac Airport's third runway. The declaration prohibits clearing, grading, filling, and construction within the mitigation area, with limited exceptions for approved wildlife management, monitoring, maintenance, and stormwater infrastructure. It was established to satisfy federal Clean Water Act requirements and state water quality standards by preserving and enhancing wetland and riparian habitat displaced by airport expansion.

This 2001 email chain among Washington State Department of Ecology staff discusses recommended criteria for fill material to be used in the Seattle-Tacoma International Airport Third Runway project. Staff member Peter Kmet proposed requiring fill material to meet ecological screening values from Table 749-3, with the uppermost six feet consisting of clean, naturally occurring soil free of manmade organic compounds and metals above natural background levels. The discussion also covers the applicability of the Model Toxics Control Act (MTCA) standards and the need to address potential impacts on plants, animals, groundwater, and aquatic organisms.

Final draft meeting notes prepared by Rachel McCrea of Floyd & Snider Inc. for 401 Permit Decision-Making technical meetings on June 25 and June 27, 2001, regarding Sea-Tac International Airport Third Runway. Attendees included Ann Kenny and John Drabek (Dept. of Ecology), Kelly Whiting (King County), Keith Smith (Port of Seattle), Paul Fendt and Tom