Notes
GeoSyntec Consultants letter dated 7 February 2002, authored by Cheryl J. Hammer, submitted to U.S. Army Corps of Engineers Regulatory Branch (Muffy Walker/Gail Terzi) on behalf of Airport Communities Coalition (ACC). Provides technical review of the Port of Seattle Sea-Tac Third Runway embankment fill low streamflow analysis, specifically critiquing the November 27, 2001 Pacific Groundwater Group (PGG) report ‘Embankment Fill Modeling in Support of Low Streamflow Analysis.’ Key findings: failure to account for initial-years water lag (1–6 years depending on embankment height: 20 ft, 110 ft, 150 ft cross-sections), overestimation of hydraulic conductivity, under-designed storage vaults, uncalibrated Hydrus and SLICE spreadsheet models, and failure to evaluate embankment soil variability. GeoSyntec independent Hydrus 2D analyses cited. Exhibit AR022134, PCHB Third Runway EIS proceeding.