TagEnvironmental Impact Statement(400)

This technical document compares observed and model-predicted 7-day low streamflows for Walker Creek and Des Moines Creek near Seattle-Tacoma Airport for water years 1991–1996. Results show that calibrated (simulated) flows generally underestimated observed flows at most gage locations, with the exception of 1995, when the model overpredicted flows. Discrepancies at upstream gage locations are attributed to uncertain groundwater conditions within the watersheds.

Parametrix, Inc. report prepared for Port of Seattle, Seattle-Tacoma International Airport Master Plan Update Improvements, December 2001. AR 052659/052660/052661. Volume 1 includes main text and Appendices B through J. Sub-consultants include Aqua Terra Consultants, Earth Tech Inc., Foster Wheeler Environmental Corporation, HNTB, and Pacific Groundwater Group. Addresses low streamflow analysis and summer low flow impact

Wetland Functional Assessment and Impact Analysis prepared by Parametrix, Inc. for Port Of Seattle, December 2001, project number 556-2912-001 (03). Assesses wetland functions and impacts associated with Seattle-Tacoma International Airport Master Plan Update Improvements including the new Third Runway, Runway Safety Areas (RSAs), relocation of South 154th Street, Borrow Area 1 excavation, South Aviation Support

Report by Pacific Groundwater Group (project JE0105) prepared for Port Of Seattle, dated November 27, 2001, analyzing embankment fill modeling in support of low streamflow analysis for the Sea-Tac Third Runway. Uses HYDRUS-SLICE modeling to assess vertical infiltration through embankment fill materials (General Fill and Type 1 Fill), saturated flow beneath the fill, and effective

Port Of Seattle letter dated November 16, 2001 from Elizabeth Leavitt, Manager of Aviation Environmental Programs, to Ann Kenny at the Washington Department of Ecology Northwest Regional Office, transmitting the Third Runway Embankment Seepage and Groundwater Monitoring Plan in satisfaction of § 401 Water Quality Certification Order #1998-4-02325, Condition E.3. The plan, AR 052417–052419, covers

This document presents site features and cross-sectional diagrams used for Hydrus-Slice hydrological modeling of the Sea-Tac Third Runway Embankment Fill project. It shows fill depths ranging from 0 to 160 feet across multiple modeled slices, with cross sections identifying impervious areas, elevation contours, and the watershed divide between Miller Creek and Walker Creek. The figures were produced in November 2001 as part of environmental engineering analysis for the third runway construction.

Port of Seattle Natural Resource Mitigation Plan figure (AR017604, Exhibit 46, dated 12-20-01) showing Master Plan Update Improvement Projects at Seattle-Tacoma International Airport (STIA). Map depicts Third Runway construction area, Runway Safety Areas (RSAs), MSE retaining walls used to avoid and minimize wetland impacts, relocated section of Miller Creek, Miller Creek Detention Facility, Lora Lake,

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,

Parametrix, Inc. prepared this Des Moines Way Nursery Mitigation Plan (AR 052455) for Port Of Seattle, Seattle-Tacoma International Airport, November 2001, project number 556-2912-001(03). The plan covers wetland restoration and enhancement at the Des Moines Way Nursery mitigation site, including grading design, expected hydrology, wildlife considerations, planting plan, vegetation monitoring, performance standards, maintenance and contingency

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