SITE INFORMATION AND CORRESPONDENCE_3

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t Mr. Robert Trommer U Comments on CUF Site Closure Recommendations for Various SitesPage 6 of 7 March 3, 2010 conducted. The EHD expects a very short remediation period that will not involve rebound testing as groundwater is currently too low to be significantly impacted. Assuming that the RP and consultant move forward on this site expeditiously, the EHD anticipates site closure in six to I nine months. I Claim No. 14558 -2353 Toste Road Tracv This site was being remediated by ozone injection at the time of the CUF site closure recommendation in May 2009. The EHD directed cessation of the ozone injection and rebound testing by letter dated June 1, 2009. Since that time, groundwater analytical results have been favorable except for variable concentration of tert-butyl alcohol in monitoring well MW-7. The TBA has not been detected in any down-gradient wells, nor has MTBE. The EHD will present this site to the CVRWQCB as a closure candidate and initiate site closure procedures. The EHD anticipates site closure in six to nine months. Claim No. 15211 -23569 Santa Fe Road Escalon During the fast reported monitoring event (September 2008); the TPHg and benzene concentrations in monitoring well MW-3 appeared to have rebounded from 790 pg/L and 2.5 pg/L to 86,000 pg/L and 270 pg/L, respectively. Concentrations of the same analytes :in MW-7 E were also elevated at 2,100 pg/L and 230 pg/L, respectively. Impacted ground water around ' MW-3 was delineated by monitoring wells in three directions while it is similarly delineated in only one direction around MW-7. The impacted groundwater is in an area of high groundwater usage; in fact MW-7 is approximately 15 feet from a domestic wellbelieved to be only 140 feet deep. In August 2008, a membrane interface probe (MIP) investigation in the core areas was conducted, but the results have not been submitted to the EHD for review. At this time the EHD believes additional monitoring of the core and inboard wells is needed to more fully understand the import of the last reported monitoring results. Additional monitoring of MW-3 and MW-7 would also be helpful. The EHD believes it would only be prudent to review the report of findings for the recent MIP investigationand conducting at least one more monitoring event before initiating site closure. The major impediment for moving forward on this site is that the RP had received significant reimbursements from the CUF, but reportedly has not paid his consultant. The consultant is not conducting any additional work and is holding back the report of the MIP investigation. Claim No. 15890 - 545 E. Miner Avenue, Stockton A vapor intrusion and ESL evaluation of the site resulted in impacted soil gas and soil exceeding acceptable contaminant concentrations. By letters dated February 1, 2008, and July 11, 2008, the EHD commented on the results of a soil gas survey and soil impact investigation, noting that the TPHg concentrations in soil gas exceeded the San Francisco Bay Regional Water Quality Control Board's (SFBRWQCB) November 2007 environmental screening levels (ESLs) and directed additional vapor intrusion evaluation and either justification for leaving soil impacted above the ESLs in place or conducting site remediation. On November 19, 2009, an additional soil gas investigation was conducted and no other site work has occurred since the fourth quarter 2008. The EHD is awaiting a report of investigation for the November 2009 work and the technical justification for leaving soil impacted above ESLs for gross contamination and direct contact in place; assuming favorable results, the EHD anticipates closing the site in six to nine months. Comments on CUF Site Closure Recommendations 0310.doc-