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} EDMU-G^_ BROWN JR. <br /> �� GOVERNOfi <br /> OALIPOWNIA <br /> MATTHEW RODRIOUEZ <br /> Water '@'' SECRETARY FOR <br /> Boards ENVIRONMENTAL PROTECTION <br /> Central Valley Regional Water Quality Control Board <br /> RECEIVED <br /> 11 July 2017 JUL 1 <br /> 3 2017 <br /> Mr. Taj M. Bahadori, PE ENVIRONMENTAL HEALTH <br /> Senior Civil Engineer PERMITISE V►SE <br /> San Joaquin County Public Works, Solid Waste Division <br /> 1810 E. Hazelton Avenue <br /> Stockton, CA 95201 <br /> NOTICE OF VIOLATION: REVIEW OF THE SECOND SEMESTER AND ANNUAL 2016 <br /> GROUNDWATER AND SURFACE WATER MONITORING REPORT FOR FOOTHILL <br /> SANITARY LANDFILL, SAN JOAQUIN COUNTY <br /> The Foothill Sanitary Landfill is owned by San Joaquin County and operated by Foothill Sanitary <br /> Landfill, Inc. The Foothill Sanitary Landfill is regulated by Waste Discharge Requirements <br /> (WDRs) Order R5-2015-0058. Central Valley Water Board staff has reviewed the Second <br /> Semester and Annual 2016 Groundwater and Surface Water Monitoring Report for the Foothill <br /> Sanitary Landfill. <br /> Unsaturated Zone Violations <br /> During July 2016, the Discharger upgraded the alternate boundary soil gas probes. Probes <br /> SG2A, -3A, -6A, -10A, and -11A were installed as triple completion wells. Single completion <br /> gas probes SG-4, -5, -7, and -9 are left to be reinstalled as triple completion. Eight of ten <br /> alternate boundary gas probes reported continued detections of VOCs during 2016. <br /> These detections indicate a release from the WMU and are a violation of WDRs Prohibitions <br /> A.2, A.4, and A.7. <br /> The remaining four alternate soil gas probes that are single completion wells are required to be <br /> reconstructed as triple completion to comply with the Detection Monitoring Program (DMP) <br /> since LFG in the vadose zone is the threat to water quality beneath the site. The alternate <br /> boundary gas probes were drilled to depths between 29 and 71 feet bgs and backfilled with <br /> 3/8-inch pea gravel to approximately five feet bgs. There exists a large open borehole that is <br /> not being monitored and likely acting as a conduit for gas migration. Furthermore, methane <br /> continues to be detected in probe SG-1, which monitors the vadose zone at a depth of 255 feet <br /> below ground surface. VOCs continue to be detected in groundwater in the vicinity of SG-1, <br /> which is evidence of LFG migration at depth. <br /> Groundwater Violations <br /> Volatile organic compounds (VOCs) have been detected in well MW-3, which is consistent with <br /> past monitoring events. This appears to be an ongoing release that with continued build out of <br /> the landfill gas (LFG) extraction system may reduce VOCs in the vadose zone. The source of <br /> KARL E. LONGLEY SOD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200.Rancho Cordova,CA 95670 1 www.waterboards.ca.gov/centralvalley <br /> `II RECYCLED PAPER <br />