1600 MADISON ST 2016-01-01 MF Import

MTCA Addendum (August 2000), only the gasoline concentration exceeds groundwater cleanup levels. Furtherntore, the new Cleanup Level for gasoline assumes :hat groundwater is used as drinking water. Therefore, the �• discovered concentrations would not be expected to pose a significant threat to human health or the environment, based on adoption of the MTCA �� amendmenfs, the planned future uses of the site, and the indication that water " discovered in VW-2 is discontinuous and not representative of groundwater. _ 7.0 RECOMMENDATInNS G-Logics recommen�is that this repoR (and the attached previcus site-assessment reports) be - fonvazded to the Wachington Department of Ecology (Ecology). This information should be " presented to Ec�logy to continue to meet the reporting provisions of 173-340-300 WAC, as explained in Ecology Policy Memo 101, dated May 25, 1990. Additional specific recommendations are: noted below. Recommendations for Petroleum-ajjected SoiL• Although petroleum hydrocazbons and benzene aze not present at concentrations that exceed MTCA Method A Soil Cleanup Levels, G-Logics recommends that the eastern and southem azeas of the former tank be over excavated during development of the site and any pockets of gasoline-contaminated soils be removed. Particulazly, this recommendation applies to the soils located in the azea of monitoring well VW-1, where some remaining contaminated soils (perhaps located beneath the station building) aopazently aze locally impacting subsurface water in this azea. The volumes of remaining contaminated soils to be excavated are estimated to be approximately 100 to 200 cubic yazds. Recommendations for Petroleum-ajjected Water: G-Logics has not identified information _ that would indicate groundwater is contaminated beneath the site, or that concentrated contaminants have migrated to a depth that might impact deeper groundwater. Additionally, the water discovered in VW-1 appezrs to be present due to the infiltration of surface water around the monitoring well and not representative of groundwater or perched groundwater. As such, the above recommendation for the over excavation of any remaining contaminated soils is anticipated to address concerns about possible groundwater contamination in this area. Therefore, typical recommendations for groundwater treatment, such as pump-and- treat or air sparging, aze not recommended for this site. Recommendations forAdditional Exploration: G-Logics recommends further exploration and sampling at this site only if additional information is required to meet the risk- 01-0105-C-RT.doc . i( S`vl(�CS � Co ht 2001 G•Logics, lnc. Page 12 of 14 �'� � PY�B