Exhibit 026593: Memorandum — Review of Draft De-Icing Dissolved Oxygen Report

Notes

Memorandum from Ken Ludwa of Parametrix, Inc. to Elizabeth Leavitt, dated June 29, 1999, reviewing the Draft De-Icing Dissolved Oxygen Report related to Sea-Tac Airport runway and taxiway acetate washoff. Comments address dissolved oxygen (DO) water quality standards (8 mg/L Class A, 9.5 mg/L Class AA) in Miller Creek and Des Moines Creek, NW Ponds, and Lake Reba. References June 9, 1998 letter from Lisa Austin of Washington State Department of Ecology regarding Port of Seattle obligation to demonstrate DO is not lowered below water quality standards by de-icing chemical runoff. Recommends statistical and time series analysis to distinguish effects of precipitation versus de-icing chemicals, and reorganization of report to emphasize non-violation of state water quality standards. CC’d to Paul Fendt, Tom Hubbard, Barbara Hinkle, Linda Logan, Scott Tobiason.

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