Notes
Northwest Hydraulic Consultants Inc. letter dated September 27, 2000, to Gordon White, Program Director, Shorelands and Environmental Assistance Program, Washington State Department of Ecology, providing third set of preliminary review comments on the August 2000 Stormwater Management Plan (SMP) for the Seattle-Tacoma International Airport Master Plan Update Improvements (third runway). Raises two core issues: (1) failure to demonstrate compliance with Governor Gary Locke’s June 30, 1997 Certification requirement that the third runway not alter the hydrologic divide between Miller Creek and Des Moines Creek affecting average instream flows; SMP basin boundary figures are based on 2006 future-condition subbasin boundaries rather than pre-development conditions, inconsistent with normal hydrologic assessment practice; (2) feasibility of stormwater peak flow control via Industrial Wastewater System (IWS) lagoon improvements not demonstrated — lack of continuous simulation modeling (HSPF), proposed Lagoon 3 expansion to 72 MG conflicts with FAA Advisory Circular 150/5200-33 Hazardous Wildlife Attractants guidelines (10,000-foot siting requirement vs. 2,000–3,000-foot actual distance), and 4 MGD processing rate assumption unconfirmed. King County September 2000 SMP review and Ecology June 9, 1998 letter (Lisa Zinner) cited. Kennedy/Jenks Consultants April 1998 IWS Engineering Report Addendum referenced.