TagThird Runway(1067)

Parametrix, Inc. summary (August 11, 1999) of key wetland findings from the Sea-Tac Runway Fill Hydrologic Studies Report (Pacific Groundwater Group 2000), prepared for the Port Of Seattle Master Plan Update Improvements JARPA review. Covers wetland delineation conservatism, limiting habitat characteristics of Miller Creek, Walker Creek, and Des Moines Creek, salmonid habitat significance, indirect embankment

A 1999 memo from the Washington State Department of Ecology evaluates construction techniques for a retaining wall near Miller Creek at Sea-Tac International Airport's Third Runway project. The memo concludes that specialized methods such as tied-back walls, bored piles, soil nailing, or ground freezing can address difficult underground soil conditions while keeping construction within the approved wetlands disturbance footprint, though at significant cost. The author also recommends installing monitoring devices in the wall and backfill to confirm the structure performs as designed throughout its service life.

Draft Wetlands Re-Evaluation Document prepared by Port Of Seattle in August 1999 for Seattle-Tacoma International Airport (STIA) Master Plan Update Improvements. Addresses new information on wetlands and aquatic resources affected by the planned new third runway and related improvements, not available during preparation of the 1996 Final Environmental Impact Statement (FEIS) or 1997 Final Supplemental

Report AR042353 prepared by HNTB, Hart Crowser Inc., and Parametrix for Port Of Seattle Aviation Program Management Group, evaluating retaining wall and slope alternatives to reduce impacts to Miller Creek at embankment station 174+00 to 186+00 for the Third Dependent Runway project at Sea-Tac International Airport. Transmitted July 13, 1999 by Barbara Hinkle to Tom

Memorandum dated July 9, 1999 from Reese P. Hastings and Michael J. Bailey, P.E. (Hart Crowser, Inc.) to Barbara Hinkle, Port Of Seattle, regarding Third Runway Project Borrow Areas 1, 3, and 4 and projected impacts to wetlands. Document J-4978-02 quantifies potential wetland resource impacts from excavation of borrow areas providing 7.9 million bank cubic

Hart Crowser subsurface conditions data report prepared for HNTB Corporation and Port Of Seattle, project J-4978-06, July 1999, supporting 404 permit for Third Runway embankment at Sea-Tac Airport. Covers generalized geologic and hydrogeologic conditions, subsurface soil conditions, hydraulic conductivity estimates, slug testing, water level data, SPT borings (HC99-B31 through HC99-B47), test pits (HC99-TP1 through HC99-TP21,

A 1999 draft assessment prepared by Parametrix, Inc. for the Port of Seattle outlines best management practices (BMPs) for managing stormwater runoff at Seattle-Tacoma International Airport as part of its Master Plan Upgrades. The document describes how the Port plans to implement water quality treatment measures—including filter strips, bioswales, and wet-vaults—across existing and newly developed stormwater drainage subbasins to meet Washington State Department of Ecology redevelopment requirements. Note that while archived alongside airport planning documents, this report focuses on stormwater and water quality compliance, not noise policy.

Technical memorandum prepared by HNTB Corporation for the Port of Seattle and Parametrix, Inc. (June 15, 1999) analyzing temporary wetland impacts during Seattle-Tacoma International Airport Third Runway embankment construction. AR 042490. Covers storm water management during construction, temporary fill in wetlands west of runway embankment toe, impacts to Wetland 37 (Miller Creek basin) and Wetland

Email chain (AR 033708–033710) among Washington State Department of Ecology staff Paula Ehlers, Tom Luster, and Raymond Hellwig, with ATG staff Tom McDonald and Joan Marchioro, dated June 1–13, 1999, regarding the Port Of Seattle third runway proposal and 401 water quality certification for Des Moines Creek. Discusses antidegradation requirements under Washington Water Quality Standards

This 1999 email exchange between Washington State Department of Ecology staff debates the legal basis for requiring the Port of Seattle to restore water quality in Des Moines Creek as a condition of receiving a Section 401 water quality certification for the Sea-Tac Airport third runway project. The central question is whether Ecology can require a single applicant to fix broader watershed problems that pre-exist their project, or whether mitigation can only address the applicant's direct project impacts. Staff ultimately conclude that under antidegradation requirements, no further degradation of the creek can be permitted until existing beneficial uses are restored, meaning the Port's mitigation plan must include measures such as flow augmentation and stormwater controls to bring the creek into compliance with water quality standards.