Notes
Exhibit 286 (AR 019661–019663), Port of Seattle 1999 Airfield Project Soil Fill Acceptance Criteria for Seattle-Tacoma International Airport (STIA). Establishes geotechnical and environmental criteria for imported fill material sourced from WDOT state-certified commercial borrow pits, contractor/supplier-certified construction sites, and Port-owned property. Environmental suitability standard is MTCA Method A contaminant levels; arsenic elevation at certain commercial sources requires supplier certification. Details two-category source certification process: Category A (industrial sites, sites listed on Ecology Confirmed and Suspected Contaminated Sites Report, Underground Storage Tank List, Leaking Underground Storage Tank List) requires environmental professional observation, TPH and metals analyses; Category B (all other sources) requires observation and interview with escalation to Category A if contamination potential identified. Washington Department of Ecology requested this description in conjunction with 401 Water Quality certification process. Port to provide quarterly fill certification submittals to Ecology. Independent consulting soil technicians to conduct in-place soil density tests (3–5 per day) during material delivery and placement.