October 30, 2001August 2, 2026

401 Permit Post-Issuance Clarification: Sea-Tac International Airport Third Runway Low Flow Analysis Final Meeting Notes

Notes

Final meeting notes from an October 30, 2001 meeting convened by the Port of Seattle to discuss errors identified in the low streamflow modeling for the Sea-Tac Airport Third Runway 401 Permit. The meeting covered six specific modeling errors and associated revisions, including a 1/24th conversion factor error in embankment fill input to HSPF, incorrect input files, and revised approaches to modeling impervious areas and infiltration basins. The notes also document an independent QA review by Hydrocomp and conclusions regarding required revisions to the Low Streamflow Analysis and Summer Low Flow Impact Offset Facility Proposal.

Sidebar On/Off

As the source for federal transportation grants, the Puget Sound Regional Council was charged with developing a system to meet the growing need for commercial aviation. When the search for a second airport failed, they authorized the Port of Seattle to build the Third Runway, with a mandate to develop a noise abatement and mitigation program. In their effort to stop the Third Runway, the ACC argued over every detail of the Port's efforts--including property buyouts and sound insulation. The dispute was meant to be settled by a three member Expert Arbitration Panel. This is their final report. It finds 2-1, that the Port's program was insufficient in several respects. Despite that, funding for the Third Runway was approved by the PSRC, and the 'Port Package' program, proceeded largely unchanged. Expert Arbitration Panel's final decision finding that the Port of Seattle had not shown sufficient reduction in real on-the-ground noise impacts to satisfy noise reduction conditions required for approval of a third runway at Sea-Tac International Airport. The majority decision concluded the Port's noise abatement programs were insufficient despite being impressive in scope.

continue...

V V

Notes

Message