SITE INFORMATION AND CORRESPONDENCE

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Mr. Robert Trommer Page 2 of 7 Comments on CUF Site Closure Recommendations for Various Sites March 3, 2010 requested very specific information regarding these issues in correspondence dated September 23, 2009, and the response report issued by the consultant, dated November 10, 2009, did not directly address any of these issues. The EHD is preparing additional correspondence requesting the specific information required by the EHD to render a professional opinion, based on reliable data, on the potential vapor intrusion issue. If these issues had been adequately addressed in the November report, the EHD believes this site would be closed now (or nearly closed). The EHD believes this site should be closed, but vapor intrusion has been identified at the State level as a potential health issue that must be addressed before closing a site. The EHD is attempting to exercise due diligence by acquiring defensible data that demonstrates that the health risk posed by potential vapor intrusion from residual contamination is at or below an acceptable level. If the California State Water Resources Control Board Cleanup Fund (CUF) technical staff can provide the EHD with additional insight on these matters, it will be carefully considered. Claim No. 8828 - 632 S. EI Dorado Street, Stockton This site has been though remediation by soil vapor extraction (SVE) and groundwater extraction (GWE). One monitoring event has been conducted since cessation of active remediation, but the extraction well was not sampled. The EHD has directed an additional monitoring event to check for rebound. Anticipating favorable results, the EHD believes the site can reach final closure in approximately six months (sampling event not yet performed or reported). Claim No. 889 - 5491 F Street, Banta A monitoring well has been installed to check for deep total petroleum hydrocarbons quantified as motor oil (TPHmo) encountered by cone penetrometer testing (CPT) sampling. The initial monitoring of the well did not detect TPHmo. The EHD plans one more monitoring of the new well to verify that TPHmo is not an issue in this area of high groundwater utilization. Anticipating favorable results, the EHD believes the site can be closed in approximately six months. Claim No. 1978 - 106 Second Street, Ripon The contaminants are generally delineated for this release, except toward the north as demonstrated by impacted CPT grab groundwater samples collected from boring CPT3 near the center of Second Street; therefore, the plume is undefined toward the north. As a municipal well was formerly located toward the northeast of the site, a work plan to obtain additional grab groundwater samples north and northeast of the site has been approved to complete plume delineation. Monitoring well MW-3 used to be the heavily impacted well, but the plume shifted to MW-2 between 2003 and 2005, and appears to be gradually declining in MW-2 since 2007. Without knowing the pumping history of the former municipal well, the EHD is concerned that the change in plume stability may be related to the change in the municipal well usage. Assuming favorable result from the grab groundwater samples, the EHD anticipates closing this site in six to nine months (to allow time to perform the field work, prepare and review the report of findings, and destroy monitoring wells). Claim No. 2612 - 110 N. Filbert Street, Stockton This site is in the closure process, and the notification paperwork for the Central Valley Regional Water Quality Control Board (CVRWQCB) is in preparation. A large number of monitoring wells need to be destroyed. The EHD anticipates final site closure in three months. Comments on CUF Site Closure Recommendations 0310.doc