TagArmy Corp of Engineers(124)

A February 2002 technical letter from GeoSyntec Consultants, submitted to the U.S. Army Corps of Engineers on behalf of the Airport Communities Coalition, raises serious concerns about the Port of Seattle's water flow analysis for the Sea-Tac Third Runway expansion project. The report argues that the Port's analysis fails to account for the years-long delay before water would flow through the new embankment fill and reach surrounding creeks, potentially leaving those creeks without adequate water during the critical early years after construction. GeoSyntec concludes that the storage vaults designed to protect creek water levels are likely undersized and that the Port has not reliably demonstrated the project will meet low streamflow requirements.

A February 2002 technical review by GeoSyntec Consultants, submitted to the U.S. Army Corps of Engineers, raises serious concerns about the Port of Seattle's low flow water analysis for the Sea-Tac Airport Third Runway expansion project. The review argues that the Port's models fail to account for the years-long delay before water would flow through the new embankment fill and reach surrounding creeks, potentially leaving those creeks without adequate water during the critical early years of operation. GeoSyntec concluded that the proposed underground storage vaults may be significantly undersized and that the Port has not reliably demonstrated the project will meet required streamflow conditions.

A January 2002 letter from Northwest Hydraulic Consultants to the U.S. Army Corps of Engineers challenges the Port of Seattle's December 2001 Low Streamflow Analysis related to Sea-Tac Airport's third runway development. The letter identifies critical flaws in hydrologic modeling of Miller, Walker, and Des Moines Creeks, including double-counting of groundwater discharges, flawed seepage modeling methodology, and failure to account for construction impacts on stream low flows. The consultants argue these errors cause the Port to substantially underestimate the project's negative impacts on local stream flows.

A January 2002 technical letter from Northwest Hydraulic Consultants challenges the Port of Seattle's December 2001 Low Streamflow Analysis for SeaTac Airport, identifying serious modeling errors that led to underestimated impacts on Miller, Walker, and Des Moines Creeks. Key flaws include double-counting of groundwater discharges in the Miller Creek model, inconsistent methodology for assessing embankment seepage, and failure to account for updated construction methods. The letter was submitted to the U.S. Army Corps of Engineers on behalf of the Airport Communities Coalition.

Parametrix, Inc. technical memorandum dated January 21, 2002, from Jim Kelley, Ph.D., to Muffy Walker, US Army Corps of Engineers Regulatory Branch, regarding Port Of Seattle permit 1996-4-02325 (Sea-Tac Airport Master Plan Update). Provides supplemental information on wetland impacts in upper watersheds of Miller Creek, Walker Creek, and Des Moines Creek, including percent loss of

A January 2002 letter from law firm Helsell Fetterman, on behalf of the Airport Communities Coalition, raises concerns with the U.S. Army Corps of Engineers about the Port of Seattle's revised construction plans for the Sea-Tac Third Runway. The Port switched from an in-place ground improvement approach to excavating up to three million cubic yards of material beneath the proposed retaining wall, a major change that critics argue could significantly harm Miller Creek and adjacent wetlands. Attached technical comments from GeoSyntec Consultants also identify deficiencies in the Port's geotechnical report and argue the changes undermine the Port's Clean Water Act Section 404 permit application.

A December 2001 letter from Azous Environmental Sciences challenges the Port of Seattle's wetland mitigation plan for the SeaTac Third Runway construction project, arguing that the plan inadequately offsets environmental damage to wetlands and streams. The letter contends that the Port has misclassified wetland 'enhancement' work at Vacca Farm as 'restoration,' inflating mitigation credits, and that the overall plan fails to meet no-net-loss standards required under Army Corps of Engineers regulations.

ACC (Airport Communities Coalition) motion for partial summary judgment filed in PCHB No. 01-160 against State of Washington Department of Ecology and Port of Seattle, arguing the Section 401 Certification should be invalidated because the Port lacks a water right to permanently mitigate low-flow impacts of the Sea-Tac Airport third runway project. Cites PCHB December

A December 2001 technical letter from Northwest Hydraulic Consultants, written on behalf of the Airport Communities Coalition, identifies inconsistencies in the Port of Seattle's stormwater management plans for Sea-Tac Airport expansion. The letter argues that the Port's hydrologic modeling failed to account for the planned commercial redevelopment of borrow pit areas by 2006, and that the Natural Resource Mitigation Plan reverted to an outdated stormwater approach relying on regional detention facilities to be built by others. These gaps, the consultants contend, prevent a full assessment of the airport Master Plan Update's environmental impacts.

Northwest Hydraulic Consultants (NHC), retained by ACC (Airport Communities Coalition), wrote to Colonel Ralph H. Graves, Ms. Muffy Walker, and Ms. Gail Terzi of the U.S. Army Corps of Engineers Seattle District (Corps Ref. No. 1996-4-02325) identifying inconsistencies in Port Of Seattle proposals for site development and stormwater management at Sea-Tac Airport Master Plan Update