1600 MADISON ST 2016-01-01 MF Import

� adjacent residential property where no detectable concentrations were noted. This report also concludes that the majority or the contaminated soil has been removed (dL,; to the presence of dense glaci3l till soils) and remaining contaminated soil "will stabilize now that the source has been removed". Z•2 Regulatory Background The rules that guide the cleanup process at sites within Washington are known as the Model Toxics Control Act (MTCA), which is administered by th<: Washington Department of Ecology (Ecology). MTCA "establishes administrative processes and standazds tc identify investigate, and ;(eanup facilities wher� hazazdous substances have come tn be located" (WAC 173-340-100). Soil and groundwater Cleanup Levels promulgated under MTCA aze used as standazds for deciding when additional investigation or cleanup is appropriTte. Therefore, for this exploration, we have compazed analytical laboratory results to publishec� MTCA Method A and/or B Cleanup Levels for soil and groundwater. However, the MTCA regulation states that published Cleanup Levels should not automatically be used to deine contaminant concentrations that must be met for financial, real estate, insurance ,:overage, or similaz purposes. Additionally, exceeding I�lTCA published Cleanup Levels does not necessarily mandate a cleanup action for a site. In addition to published cleanup levels for petroleum hydrocazbons under MTCA, Ecology also allows ar; evaluation of their toxicity and solubiliry in order to identify appropriate cleanLp levels. This approach is called the Interim TPH Policy and provides a means of evaluating the health hazazd and leachabiliry of peholeum hydrocazbons that remain in subsurface soil based on the chemical composition of the hydrocarbons. tn general, hydrocarbon toxicity and leachability (the likelihood that a chemical will travel from soil into groundwatcr) decrease as the r�umber of cazbons in a hydrocarbon molecule increase. A cleanup-level evaluation using the Interim TPH Policy was not performed as part of this assessment, but can be conducted if required. Amendments to the MTCA regulations also aze neazly complete, with several proposed ( changes to the published Method A Cleanup Levels. For this si:,;, most of the cleanup levels � will go up, reflecting the current understandin of the risks osed b B p y petroleum- � hydrocarbon compounds. 01-OIOS�C•RT.doc . O 9��'J'C's' Copyright 2001 G•Logics, Inc. Page 5 af 14 J �