TagPollution Control Hearings Board(1532)

A study at Seattle-Tacoma International Airport found that galvanized metal roofing on cargo buildings was the primary source of elevated zinc levels in the airport's stormwater runoff, which drains into salmon-bearing streams including Miller Creek and Des Moines Creek. Researchers used whole effluent toxicity (WET) testing and source-tracing methods to identify the problem, focusing on one outfall (SDN1) that consistently showed higher zinc concentrations and toxic effects on aquatic organisms. The findings prompted the Port of Seattle to investigate remediation options as part of its stormwater pollution prevention program under its NPDES permit.

Parametrix, Inc. prepared this Des Moines Way Nursery Mitigation Plan (AR 052455) for Port Of Seattle, Seattle-Tacoma International Airport, November 2001, project number 556-2912-001(03). The plan covers wetland restoration and enhancement at the Des Moines Way Nursery mitigation site, including grading design, expected hydrology, wildlife considerations, planting plan, vegetation monitoring, performance standards, maintenance and contingency

Memorandum dated November 1, 2001 from Elizabeth Leavitt (Port Of Seattle) to Muffy Walker (U.S. Army Corps of Engineers) regarding Army Corps Section 404 review of on-site borrow areas for Sea-Tac Airport Third Runway embankment fill. Covers Borrow Areas 1, 3, and 4 located in Des Moines and SeaTac; combined 6.1 million cubic yards of

Final Natural Resource Mitigation Plan (NRMP) prepared by Parametrix, Inc. for the Port Of Seattle, covering Master Plan Update Improvements at Seattle-Tacoma International Airport (Sea-Tac Airport). Document number 556-2912-001 (03), dated November 2001. Administrative Record document AR 029275–AR 029277.

Port of Seattle Natural Resource Mitigation Plan figure (AR017604, Exhibit 46, dated 12-20-01) showing Master Plan Update Improvement Projects at Seattle-Tacoma International Airport (STIA). Map depicts Third Runway construction area, Runway Safety Areas (RSAs), MSE retaining walls used to avoid and minimize wetland impacts, relocated section of Miller Creek, Miller Creek Detention Facility, Lora Lake,

Natural Resource Mitigation Plan for Seattle-Tacoma International Airport (STIA) Master Plan Update, November 2001, document reference 556-2912-001 (03). Table 1.3-1 lists all proposed Master Plan Update improvement projects including: third parallel runway 16X/34X (8,500 ft), Runway Safety Areas (RSAs) for 16R/34L and 16L/34R, South 154th Street relocation, South Aviation Support Area (SASA) for cargo/maintenance, embankment

A November 2001 email chain discusses a meeting held on October 30, 2001, regarding errors discovered in a low flow analysis related to environmental modeling near Seattle. Raymond Hellwig of NWRO confirms that revisions to the low flow analysis may be considered to correct previous modeling errors, but stresses that any revised submissions must include thorough documentation and clear rationale. The correspondence involves multiple agencies and contractors, including Floyd Snider McCarthy, Inc., the U.S. Army Corps of Engineers, and Port of Seattle representatives.

US Army Corps of Engineers Regulatory Guidance Letter No. 01-1, dated 31 October 2001, providing guidance for the establishment and maintenance of compensatory mitigation projects under Section 404(a) of the Clean Water Act and Section 10 of the Rivers and Harbors Act of 1899. Covers debit/credit assessment methodology, role of preservation, inclusion of upland areas,

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

These draft meeting notes from October 30, 2001 document a technical review session in which Port of Seattle consultants disclosed and explained several errors found in the low streamflow modeling for the Sea-Tac Airport Third Runway project. The key errors included a 1/24th magnitude conversion factor mistake in embankment fill data input, incorrect input files used for embankment modeling, and an overlap in which approximately 8 acres of the Walker Creek embankment appeared to be counted in both the Hydrus embankment model and the HSPF stream model. The meeting outlined corrective steps to be taken by the Port's consulting team to fix these errors before finalizing the revised Low Streamflow Analysis required under 401 Permit conditions.