EXH AR046044: Sea-Tac Third Runway – Borrow Area 3 Preservation of Wetlands Memorandum

Notes

Memorandum dated October 20, 2000 from Michael A.P. Kenrick, P.E. and Michael J. Bailey, P.E. of Hart Crowser to Jim Thomson of HNTB regarding Sea-Tac Third Runway Borrow Area 3 wetland preservation, project J-4978-06, prepared for Port Of Seattle. Covers hydrology sustaining Wetlands 29, B9, 30, B7, B6, and B5 in Borrow Area 3, including perched groundwater zone, Indianola series soils, glacial drift outwash, interflow, deep percolation, and why excavation will not drain the wetlands. References Hart Crowser 1999 and 2000 subsurface investigations and Parametrix 1999 Wetland Delineation Report. Discusses proposed drainage swale design, seepage gradient changes, and black muck organic soils.

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