TagArmy Corp of Engineers(124)

Letter dated November 26, 2001, from Northwest Hydraulic Consultants (on behalf of ACC, Airport Communities Coalition) to Colonel Ralph H. Graves, Ms. Muffy Walker, and Ms. Gail Terzi of U.S. Army Corps of Engineers, Seattle District, Corps Ref. No. 1996-4-02325. Identifies serious flaws in Port Of Seattle’s low flow mitigation analysis for Miller Creek, Walker

A November 2001 letter from Northwest Hydraulic Consultants, written on behalf of the Airport Communities Coalition, raises serious technical objections to the Port of Seattle's proposed plan to manage low streamflow impacts from SeaTac Airport's third runway construction on Miller, Walker, and Des Moines Creeks. The letter argues that the Port's analysis contains critical flaws, including an incorrect assumption that virtually all runway runoff infiltrates into adjacent grassed filter strips, and that the use of hourly rather than shorter time intervals in hydrological modeling causes stream impacts to be underestimated and mitigation storage facilities to be undersized. The consultants also express concern that the Port was not adequately addressing outstanding public comments or certification requirements set by regulatory agencies such as the Washington Department of Ecology.

Hart Crowser, Inc. geotechnical summary report prepared for the Port of Seattle for presentation to the U.S. Army Corps of Engineers (Seattle District), dated November 2, 2001, project number 4978-06. Covers design of the Third Runway embankment and three mechanically stabilized earth (MSE) retaining walls (50–135 feet height) at Seattle-Tacoma International Airport (STIA). Addresses 17,000,000

This November 2001 document from Parametrix, Inc. contains responses to U.S. Army Corps of Engineers questions regarding the Sea-Tac International Airport (STIA) Master Plan Update's natural resource mitigation project. It addresses technical questions about wetland mapping, watershed basin sizes, low-flow analysis, and cumulative wetland impacts across the Miller Creek, Walker Creek, and Des Moines Creek basins, showing projected wetland acreage reductions of approximately 3-4% with the project. The document also covers mitigation measures including wetland restoration sites and performance standards for invasive species control.

Hart Crowser geotechnical summary report (project 4978-06) prepared for the Port of Seattle for presentation to the U.S. Army Corps of Engineers, November 2, 2001. Covers Third Runway embankment construction at Seattle-Tacoma International Airport: 17,000,000 cubic yards compacted earth fill, maximum fill thickness 165 feet, 2H:1V side slopes, three Mechanically Stabilized Earth (MSE) retaining walls

Memorandum dated November 1, 2001 from Elizabeth Leavitt (Port Of Seattle) to Muffy Walker (U.S. Army Corps of Engineers) regarding Army Corps Section 404 review of on-site borrow areas for Sea-Tac Airport Third Runway embankment fill. Covers Borrow Areas 1, 3, and 4 located in Des Moines and SeaTac; combined 6.1 million cubic yards of

Report prepared by Parametrix, Inc. for Port Of Seattle regarding the Miller Creek Riparian Corridor and Instream Enhancement Project and Wetland A17 Restoration, part of the Seattle-Tacoma International Airport Master Plan Update Improvements. Document AR 052286 covers wetland mitigation design, Army Corps of Engineers requirements, buffer averaging, hydrology, soils, vegetation, grading, landscape plan, performance standards,

US Army Corps of Engineers Regulatory Guidance Letter No. 01-1, dated 31 October 2001, providing guidance for the establishment and maintenance of compensatory mitigation projects under Section 404(a) of the Clean Water Act and Section 10 of the Rivers and Harbors Act of 1899. Covers debit/credit assessment methodology, role of preservation, inclusion of upland areas,

Memorandum dated October 30, 2001 from Michael Kenrick of Hart Crowser, Inc. to Jim Thomson of HNTB (project number 4978-06), CC Elizabeth Leavitt of Port Of Seattle, regarding wetland hydrology impacts of the Third Runway Embankment Fill at Sea-Tac Airport. Covers depression wetlands, slope wetlands, and riparian wetlands; references FEIS for the Master Plan Update

Memorandum dated October 30, 2001 from Michael Kenrick of Hart Crowser, Inc. to Jim Thomson of HNTB, CC Elizabeth Leavitt of Port Of Seattle, project number 4978-06. Addresses wetland hydrology impacts of Third Runway Embankment Fill construction at Sea-Tac Airport, covering depression wetlands, slope wetlands, and riparian wetlands. References Miller Creek and Walker Creek baseflow,