Notes
Final meeting notes from October 30, 2001 Low Flow Analysis meeting regarding Port Of Seattle’s revisions to the Low Streamflow Analysis and Summer Low Flow Impact Offset Facility Proposal per 401 Permit conditions for Sea-Tac Airport Third Runway. Attendees included Ann Kenny (Dept. of Ecology), Kelly Whiting and David Masters (King County), Lisa Scott (Corps of Engineers), Keith Smith and Robin Kordick (Port Of Seattle), Paul Fendt (Parametrix), Joe Brascher (Aquaterra), Pony Ellingson (Pacific Groundwater Group), Felix Kristanovich (Foster Wheeler), and Kate Snider (Floyd Snider McCarthy). Six modeling errors are described and corrected: (1) 1/24th conversion factor error in HSPF embankment fill input causing 24x underestimate of embankment flow contribution; (2) incorrect daily AGWO vs. hourly AGWI input files for embankment modeling; (3) revised direct modeling of impervious area at embankment filter strips using AGWI and SURO time series data; (4) switch from 2-d to 1-d Hydrus model; (5) modeling of discharge from infiltration basins in Miller Creek basin; (6) inaccurate predeveloped groundwater routing for SDS-5,6&7 in Des Moines Creek Basin. QA review by Norm Crawford of Hydrocomp (HSPF developer) also documented; recommendation to route ‘seepage to till’ directly to creek was rejected by Port, Ecology, and King County.