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• Geo -Logic ASS O C I ATE S Geologists, Hydrogeologists and Engineers San Joaquin County Department of Public Works 1810 E. Hazelton Avenue Stockton, California 95205 • December 15, 2011 JN 2011-0115 Attention: Mr. W. Michael Carroll SUBMITTAL OF WELL COMPLETION REPORT FOR THE EVALUATION MONITORING PROGRAM AT THE CORRAL HOLLOW SANITARY LANDFILL, SAN JOAQUIN COUNTY, CALIFORNIA Geo -Logic Associates is pleased to provide the San Joaquin County Department of Public Works (County) with the attached Well Completion Report for the Evaluation Monitoring Program (EMP) at the Corral Hollow Sanitary Landfill (CHSL). This document fulfills a reporting requirement outlined in an Order to the County from the Central Valley Regional Water Quality Control Board (RWQCB) staff dated July 7, 2011. As described in the report, three temporary wells were installed and sampled in accordance with the EMP workplan approved by the RWQCB staff. Volatile organic compounds (VOCs) were detected in primary and verification samples collected from each temporary well, suggesting that the three temporary well sites are within the VOC plume that extends to the north of the CHSL. In order to determine the extent of the plume and fulfill that requirement of the EMP workplan, three additional well locations are proposed. The "step -out" wells will be located where VOC concentrations are estimated to be at non-detectable levels based on extrapolation of the isoconcentration contours for total VOCs. These three "step -out" wells will be drilled, logged, and sampled in accordance with the methods outlined in the approved EMP workplan . Once well construction is completed, a revised Well Completion Report will be prepared and submitted to the RWQCB. Afterward, the findings and conclusions from the EMP investigation will be compiled and presented to the RWQCB, followed by an Engineering Feasibility Study outlining the County's proposed course of corrective action. The attached report has been developed based on the data described therein. Our firm should be notified if conditions are found that differ from those described in this report, since this may require a re-evaluation of the conclusions and recommendations. If you have any questions regarding this letter, please call me at (858) 451-1136 at your convenience. Geo -Logic Associates i 4, e� XhnM.ower, CEG Supervising Geologist CC: Steve Sarantopoulos, GLA -Grass Valley 11415W. Bernardo Court, Suite 200, San Diego, California 92127 Phone: (858) 451-1136 FAX: (858) 451-1087 7