TagStormwater(385)

Low Streamflow Analysis prepared by Earth Tech, Inc. for Port Of Seattle as part of the Seattle-Tacoma Airport Master Plan Update, dated December 2000. Report covers existing streamflow conditions, watershed modeling of current and proposed conditions, hydrologic behavior of runway fill, non-hydrologic flows, secondary recharge effects, reserved stormwater release, and summary of low streamflow effects

The Industrial Wastewater System (IWS) at Seattle-Tacoma International Airport was built in 1963 to collect and treat runoff from airport aprons, taxiways, hangars, and maintenance areas that may be contaminated by fuel spills, de-icing chemicals, and aircraft wash water. The system channels wastewater through two main drainage areas to an on-site treatment plant, with treated water ultimately discharged into Puget Sound under an NPDES permit. Ongoing upgrades aim to expand the system's capacity to handle a 25-year design storm event.

Section 4.5.2 of the Comprehensive Stormwater Management Plan for STIA Master Plan Update Improvements, December 2000, Port of Seattle. Documents stormwater quality monitoring data from SDS outfalls (1994–2000) under NPDES Permit requirements. Table 4-8 compares STIA runoff quality against regional and national urban stormwater benchmarks including Bellevue Sturtevant Creek, Bellevue Urban Runoff Program (BURP), King

This technical document describes hydrological modeling conducted for the Seattle-Tacoma International Airport (Sea-Tac) Master Plan Update, focusing on stormwater runoff analysis for Des Moines Creek, Miller Creek, and Walker Creek subbasins. It details the calibration of computer models using rainfall and evaporation data spanning October 1948 through September 1996, along with parameters for airport embankment fill materials. The analysis was used to evaluate future stormwater detention facility requirements associated with airport expansion projects, including the Third Runway.

Letter and proposal from Dyanne Sheldon, Principal of Sheldon & Associates, Inc. (Seattle, WA), addressed to Erik Stockdale at Washington State Department of Ecology, dated November 21, 2000, submitting a proposal to review the Natural Resource Mitigation Plan (NRMP) for the Sea-Tac Third Runway. The letter discusses cost estimate exceeding the provided $18,000 budget, justifying

Final draft meeting notes from Sea-Tac Airport Third Runway 401 Permit Negotiations meeting held November 7, 2000, prepared by Kate Snider of Floyd & Snider Inc. Attendees included Ray Hellwig, Kevin Fitzpatrick, and Ann Kenny from Washington Department of Ecology; Elizabeth Leavitt from Port Of Seattle; David Masters from King County; and Paul Fendt and

This 2000 Washington State Department of Ecology policy document establishes procedures for how stormwater discharges must comply with water quality standards under Sections 401 and 402 of the Federal Clean Water Act. It outlines how Best Management Practices (BMPs), including Supplemental Treatment, should be applied to control stormwater pollution, and defines how compliance decisions are made for various permit types. The policy applies to Ecology Water Quality and SEA Program staff when reviewing or permitting projects that have stormwater impacts.

Port Of Seattle report (AR 043696, Volume 1) examining effects of runway deicing chemicals on dissolved oxygen in receiving waters at Seattle-Tacoma International Airport for the 1999-2000 winter season. Documents ground deicing chemical applications including potassium acetate (PA, Cryotech E36 LRD), sodium acetate (SA), and calcium magnesium acetate (CMA) on airfield, ramp, and landside roadways.

Final draft meeting notes prepared by Kate Snider of Floyd & Snider Inc. for the Sea-Tac Airport Third Runway 401 Permit Negotiations meeting held October 31, 2000, 8:00–11:00 AM. Attendees included representatives from Washington State Department of Ecology (Ray Hellwig, Kevin Fitzpatrick, Ann Kenny), Port Of Seattle (Michael Cheyne, Elizabeth Leavitt, Keith Smith), King County

These draft meeting notes from October 27, 2000 document technical negotiations between the Port of Seattle and the Washington Department of Ecology regarding the 401 water quality permit for the Sea-Tac Airport Third Runway project. The meeting covered topics including stormwater management planning, base flow impacts, Tyee Pond buffer requirements, and staffing for permit review. A master list of technical issues was maintained to track which items had been resolved, were pending additional information, or required further discussion.