TagEnvironmental Impact Statement(325)

Memorandum dated October 20, 2000 from Michael A.P. Kenrick, P.E., and Michael J. Bailey, P.E. of Hart Crowser to Jim Thomson at HNTB (project J-4978-06), prepared for Port Of Seattle regarding Sea-Tac Third Runway Borrow Area 3 wetland preservation. Reviews hydrology sustaining Wetlands 29, B9, 30, B7, B6, and B5 in Borrow Area 3, located

Memorandum dated October 13, 2000 from Michael Bailey P.E. and Michael Kenrick P.E. of Hart Crowser to Jim Thomson P.E. at HNTB (project J-4978-06), analyzing infiltration into the proposed Third Runway embankment at Sea-Tac Airport and effects on shallow water-bearing zone base flow to Miller Creek and adjacent wetlands. Analysis uses three sequential models —

Email chain AR 018494 in which Erik Stockdale (Washington State Department of Ecology, ESTO461@ECY.WA.GOV) sends internal memo to Gail Terzi and Jonathan Freedman (Army Corps of Engineers) outlining status of the natural resource mitigation plan and associated documents for Sea-Tac Airport expansion. Stockdale notes the Port of Seattle is objecting to Ecology’s choice of consultant

Hart Crowser draft report prepared for Port of Seattle, August 9, 2000 (J-4978-13), evaluating perched groundwater zone interception and potential wetland hydrology impacts from Borrow Area 3 excavation for the Sea-Tac Third Runway project. Addresses Pacific Groundwater Group (PGG, 2000) concerns commissioned by Washington State Department of Ecology regarding impacts to Wetland 29. Includes ModFlow

Biological Assessment prepared by Parametrix, Inc. for the Federal Aviation Administration and Port Of Seattle regarding reinitiation and initiation of Section 7 ESA consultation for Seattle-Tacoma International Airport Master Plan Update Improvements. Covers ESA-listed species managed by USFWS and NMFS including Chinook salmon, bull trout, and essential fish habitat (EFH). Analyzes hydrologic systems including Miller

Port Of Seattle SEPA Addendum (POS SEPA No. 00-07) dated May 5, 2000, to the Final Supplemental Environmental Impact Statement for the Proposed Master Plan Update Development Actions at Seattle-Tacoma International Airport (STIA), issued jointly by FAA and Port Of Seattle in May 1997. Documents the Auburn Wetland Mitigation Project on an approximately 67-acre parcel

Northwest Hydraulic Consultants submitted follow-up technical comments in May 2000 raising serious concerns about flawed stormwater modeling used to assess the impact of a proposed third runway at Seattle-Tacoma International Airport. The consultants identified major inconsistencies in soil-type assumptions and runoff parameters in the hydrologic models, concluding that the Stormwater Management Plan's predictions of detention facility performance were unreliable and required a complete overhaul. The letter also flagged a lack of adequate local regulatory oversight to ensure that Port of Seattle stormwater designs complied with King County surface water standards.

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.

SEPA Addendum (April 27, 2000) prepared by Port Of Seattle and FAA as addendum to the Final Supplemental Environmental Impact Statement for the Proposed Master Plan Update Development Actions at Seattle-Tacoma International Airport (STIA), and to the SEPA Environmental Checklist for the Auburn Wetland Mitigation Project (August 1998). Documents modification to Master Plan Update wetland

A February 2000 email from hydraulic consultant Bill Rozeboom argues that the proposed expansion of Sea-Tac Airport's Integrated Wetlands System (IWS) lagoon—tripling its storage capacity—is primarily driven by the airport's Master Plan Improvements, including the proposed third runway, rather than being a routine water quality project. Rozeboom notes that the planned increase in impervious drainage area (roughly 521 additional acres) closely mirrors the proposed increase in IWS storage volume, supporting his conclusion that the third runway is the primary driver of the expansion. He also raises concerns that the environmental documents fail to adequately assess the impact of large-scale out-of-basin water transfers on aquifer recharge and stream base flows in the Miller Creek and Des Moines Creek basins.