TagModel Toxics Control Act(32)

This Washington State regulation (WAC 173-340-747) establishes methods for determining safe soil contamination levels that protect groundwater quality at cleanup sites. It outlines several scientific approaches, including three-phase and four-phase partitioning models, leaching tests, and empirical demonstrations, to calculate the maximum allowable concentration of hazardous substances in soil before they risk contaminating groundwater. The regulation requires that soil concentrations not cause groundwater cleanup level exceedances and not result in the buildup of nonaqueous phase liquids in or on groundwater.

Exhibit AR017360, Part IX Tables from MTCA Cleanup Regulation WAC 173-340-900, dated February 12, 2001. Contains Table 720-1, Method A Cleanup Levels for Ground Water, listing hazardous substances including arsenic, benzene, benzo(a)pyrene, cadmium, chromium, DDT, 1,2-dichloroethane (EDC), ethylbenzene, ethylene dibromide (EDB), lead, lindane, methylene chloride, mercury, MTBE, naphthalenes, PCB mixtures, radium 226, tetrachloroethylene, toluene, trichloroethylene,

A January 2001 letter and accompanying meeting notes document communications between the Port of Seattle and the Washington Department of Ecology regarding a groundwater contamination study at Seattle-Tacoma International Airport, conducted under the Model Toxics Control Act (MTCA) Agreed Order 97TC-N112. The records outline the scope of the study, which focuses on hydrogeologic investigation and a review of the Fuel Operations Area, and clarify that any necessary cleanup would be handled separately after the study's completion. Both parties discussed concerns about scope expansion and the process for addressing contaminated sites identified through the study.

A scientist retained by the Airport Communities Coalition wrote to the EPA in December 2000, raising serious concerns about the Port of Seattle accepting contaminated fill materials for the proposed Third Runway project at Seattle-Tacoma International Airport. The letter argues that the Port improperly used Washington State's Model Toxics Control Act (MTCA) cleanup standards as fill acceptance criteria, when those standards were designed to clean up existing contaminated sites, not to permit introducing pollution onto previously clean land. The scientist also criticizes the Port's soil testing methods as statistically inadequate to detect the true extent of contamination, warning that chemicals in the fill could leach into groundwater, wetlands, and surface water including Miller Creek.

Email chain dated September 11, 2000 among Kevin Fitzpatrick, Peter Kmet, Chung K. Yee, Joan Marchioro, and Tom Luster of Washington State Department of Ecology (Water Quality Program, NWRO) regarding clean fill criteria language for the 401 Water Quality Certification on the Sea-Tac Third Runway project. Document marked ‘Deliberative Document Currently Exempt From Public Disclosure.’

Internal email dated September 11, 2000 from Peter Kmet to Chung K. Yee (cc: Kevin Fitzpatrick) discussing new Method A soil cleanup levels under MTCA (Model Toxics Control Act) and their use as a basis for defining clean fill. Kmet addresses specific chemicals including arsenic (recommends 7 PPM background value from USGS statewide study instead

A March 2000 Parametrix memorandum reports the results of pesticide and herbicide soil testing at the Vacca Farm site, part of the Port of Seattle's Third Runway Project. Of 59 compounds tested, only 12 were detected, primarily organochlorine pesticides, with Dieldrin slightly exceeding cleanup levels in shallow soil samples at two locations in the proposed floodplain area. The memo recommends removing the upper six inches of soil from the floodplain area for offsite disposal, while concluding that the proposed Miller Creek relocation corridor does not pose unacceptable risks to human health.

This 1999 plan, prepared jointly by the Washington State Department of Ecology and the Port of Seattle, outlines how the public will be involved in a ground water study at Seattle-Tacoma International Airport. The study was prompted by decades of jet fuel and petroleum product releases from underground storage tanks and fuel systems in the Airport's Aircraft Operations and Maintenance Area, which contaminated soil and ground water across 13 known sites. The plan describes required and additional public participation activities, community outreach roles, and the two-phase study approach, which included computer modeling of ground water flow to assess contamination risks to public water supplies and surface water.

Washington State Department of Ecology publication #94-145 (updated 1/96) presenting the February 1996 annual update to the MTCA (Model Toxics Control Act) Cleanup Standards under CLARC II. Covers Method B and Method C cleanup levels for soil and groundwater, reference doses (RfD), cancer potency factors, hazard quotients, WAC 173-340-740 and WAC 173-340-745 calculations, inhalation correction

This 1995 Washington State Department of Ecology document provides guidance for cleaning up soils contaminated by petroleum products. It outlines remediation standards and procedures under the state's Toxics Cleanup Program, applicable across all regions of Washington State. Note: This document addresses soil contamination cleanup and does not contain content specifically related to Sea-Tac Airport noise policy.