SITE INFORMATION AND CORRESPONDENCE

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• • Mr. Frank Barone - 3 - 18 August 2005 will be too late to effectively remediate the pollution. Alternatively, there are off-site monitoring wells closer to the site that should be used as indicator wells. MSRMshould identify two thresholds. One is protection of human health from off-site residents overlying the plume, and the other should identify if the plume is migrating. Since shallow groundwater is not a source of drinking water for the overlying residents, the health concern relates to vapor transmission of volatile organic compounds. The Contingency Plan should identify specific steps that will betaken if either of these thresholds is exceeded. • For the second encountered groundwater aquifer(intermediate zone),MSRM proposes to implement the alternative remediation if constituents exceed the cleanup levels and are not also present in the upgradient intermediate zone monitoring well, MW-17. Regional Board staff concur with this proposal. • If a groundwater depression is not apparent beneath the site by the summer of 2008, MSRM will implement the alternative remediation. Regional Board staff concur with this proposal. MSRM proposed a deed restriction limiting future uses of the site to industrial. Regional Board staff prefer to postpone the consideration of institutional controls until residual contaminant levels are known. The site may ultimately meet residential health standards, in which case a deed restriction will not be necessary. In summary, please revise the Contingency Plan to identify thresholds that will indicate a potential threat to human health and plume migration, and identify specific actions that will be taken should a threshold be exceeded. Please provide the Revised Contingency Plan by 21 October 2005. Regional Board staff concur with the phytoremediation operation and maintenance elements of the Groundwater Cleanup Plan provided MSRM make the following changes to the soil sampling program commencing with the fall 2005 sampling event: • Add analyses for triazine compounds (EPA Method 619) and chlorinated herbicides (EPA Method 8151), and MSRM may remove analyses for organophosphorous compounds, volatile organic compounds, and fumigants. If you have y que tions, you may contact me at(916)464-4680. AMY TERRELL Private Sites Cleanup Unit cc: Mr. Michael Infurna, San Joaquin County Environmental Health Department Mr. Alan Prouty, J.R. Simplot, Boise ID Mr. Kyle Rutherford,UNOCAL, San Luis Obispo Mr. Timothy Souther, Geomatrix, Fresno Mr. David Hahn, Crosswinds of California, Inc., Stockton Ms. Lynda Brothers, Esq., Sonnenschein Nath and Rosenthal, San Francisco