TagStormwater(373)

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.

Port Of Seattle memo opposing Airport Communities Coalition (ACC) motion for stay in PCHB No. 01-133, Volume 2 of 3, containing Declaration of Paul S. Fendt and SMP Volume 3 materials. Includes preface to the Comprehensive Stormwater Management Plan (SMP) for Seattle-Tacoma International Airport Master Plan Update Improvements, July 2001, with replacement pages developed in

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.

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

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

Northwest Hydraulic Consultants submitted follow-up technical comments to the U.S. Army Corps of Engineers and Washington State Department of Ecology regarding stormwater, hydrology, and hydraulics concerns related to the proposed third runway at Seattle-Tacoma International Airport. The letter, written on behalf of the Airport Communities Coalition, challenges the Port of Seattle's responses to earlier criticisms, raising unresolved issues about stormwater management standards, independent design review, cost estimates for detention facilities, and the accuracy of hydrological modeling. Key concerns include ambiguity in which stormwater standards will apply, inadequate quality assurance processes, and inconsistencies in the project's Stormwater Management Plan.