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THOMAS M.GAU P.O.BOX 1810-1810 E.HAZELTON AVENUE DIRECTOR STOCKTON,CALIFORNIA 95201 (209)468-3000 FAX(209)468-2999 www.sigov.org/pubworks FRITZBUCHMAN DEPUTY DIRECTOR Werung f(w YOU MICHAEL SELLING DEPUTY DIRECTOR STEVENVWNKLER DEPUTY DIRECTOR ROGER JANES BUSINESS ADMINISTRATOR RECEIVED August 20, 2012 A'U"1; 2 3 2'01'!/-' Mr. Todd Del Frate, PIG ENVIRONMENTAL HEALTH California Regional Water Quality Control Board PERMITISERVICES 11020 Sun Center Drive, #200 Rancho Cordova, California 95670 SUBJECT: EVALUATION MONITORING PROGRAM (EMP) REPORT— PHASE 11 CORRAL HOLLOW SANITARY LANDFILL Dear Mr. Del Frate: Enclosed, please find the Evaluation Monitoring Program Report—Phase //, prepared by Geo- Logic Associates. This report presents results and discussion of the second set (Phase 11) of off-site monitoring wells installed to characterize the nature and extent of shallow groundwater impact near the Corral Hollow Landfill in accordance with the Order for Technical Reports issued by the California Regional Water Quality Control Board —Central Valley Region (RWQCB) dated July 7, 2011 (the Order). The Groundwater Monitoring Well Installation Report presenting the installation of these Phase 11 wells was submitted May 7, 2012. Data collected from these Phase 11 wells are sufficient to characterize the nature and extent of shallow groundwater impact. I believe the conclusions of this report are encouraging. Phase 11 wells show decreasing concentrations of volatile organic compounds (VOCs) with increasing distance from the landfill, consistent with previous data. Geo-Logic reports that VOC concentrations beyond the landfill property are apparently below State and Federal maximum contaminant levels. In addition, third quarter groundwater monitoring at the Phase 11 wells show decreased concentration of all landfill VOCs in each Phase 11 well, compared to the Phase 11 EMP data. It therefore appears that human health and safety is not threatened by the present condition of the groundwater. Further corrective action, such as installing additional landfill gas wells included in the upcoming closure project, is anticipated to further improve the situation. As you and I discussed on November 21, 2011, the data from the first three off-site wells (Phase 1) did not allow us to characterize the nature and extent of shallow groundwater impact. To comply with the schedule of the items on Page 4 of the Order, it was agreed that the installation of Phase I wells would be presented in a Groundwater Monitoring Well Installation Report(item 2), and data collected from those wells would be presented in an Evaluation Monitoring Program Report(Item 3). Those reports were submitted in accordance with that schedule.