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composite liner comprised of a geocomposite clay layer (GCL) under a 60-mil HDPE membrane as an approved engineered alternative to the prescriptive composite liner of Title 27 and RCRA Subtitle D. In addition, a one-foot thick layer of soil with not less than 30% passing 200 sieve, compacted to not less than 90% relative density, was constructed under the composite liner. The interface between Areas 3 and 4 is a lined anchor trench/berm, raised approximately three feet above the surrounding surfaces. COMPLIANCE SUMMARY Data from the groundwater wells at the North County Landfill did not indicate impact until three VOCs were confirmed at low concentrations in well G-4 in July 2002. Because G-4 is at the western property boundary, County staff contacted the neighbor immediately to the west, requesting permission to drill temporary groundwater monitoring wells to determine the extent of groundwater impact according to the "step out, step down" approach. That property owner did not grant this request but allowed County staff to sample the water from the well on that property. No contaminants were detected. County staff therefore implemented a phased approach for evaluation monitoring within the landfill property. The first phase was to install and monitor the new groundwater well G-6 and the soil gas wells that were installed in 2003 with Area 4. Under Evaluation Monitoring, groundwater and soil gas were sampled quarterly (the WDRs require semi-annual sampling). The soil gas wells on the landfill property boundary were also used to monitor for off-site migration of landfill gas in accordance with CCR Title 27 Section 20925. In the January 2003 monitoring event, new groundwater well G-6 indicated no groundwater impact, while at well G-4, one VOC was detected.. VOCs above the trace level have not been detected at G-4 since January 2003. All other groundwater wells continued to be free of VOCs. Note that VOCs are found at many of the soil gas wells, but not in the groundwater, indicating that the presence of VOCs in the soil does not necessarily indicate the potential for impact to groundwater at this site. Although groundwater impact has not been seen since January 2003, the results of the first phase of evaluation monitoring allowed the County to delineate the problem sufficiently to proceed with engineering feasibility of corrective action options. It was apparent that the cause of the impact at G-4 was landfill gas (LFG), and that sporadic detections at G-4 could occur in the future unless corrective action was taken. After evaluating soil gas extraction as a possible method to prevent further impacts to G-4, the County submitted an addendum to the Engineering Feasibility Study with associated Amended Report of Waste Discharge (December 21, 2004). This addendum proposed active LFG collection. In accordance with the Report of Waste Discharge (January 29, 2010), all groundwater monitoring wells will continue to be sampled semi-annually for field and monitoring parameters per the WDRs. Soil gas continues to be sampled semi-annually per the WDRs. This data is included in semi-annual reports for this site. 1 North County RC&SL Public Works/Solid Waste 1"Semiannual 2014 Groundwater Monitoring 2 County of San Joaquin—July 31,2014