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The first encountered groundwater is 145 to 157 feet below ground surface. Groundwater elevations range from-30 feet -42 MSL, fluctuating seasonally approximately 6 feet. The groundwater is unconfined. Construction Details of construction are contained in the Waste Discharge Requirements for this site. Modules 1 and 2 were constructed as a single module in 1991, excavated to a depth of approximately 88 feet NGVD. This Module is provided with a 60-mil HDPE liner installed over a 6-inch (minimum) thick layer of compacted native soil, but was not constructed according to Title 27 and RCRA Subtitle D. For clarity in future reports and documents, this module will be referred to as Module 1. Module 3 was constructed in 1995, excavated to a depth of approximately 60 ft NGVD. This Module is provided with a composite liner comprised of a geocomposite clay layer (GCL)under a 60 mil HDPE membrane, which was approved as an engineered alternative to the prescriptive composite liner of Title 27 and RCRA Subtitle D. The interface between Modules 1 and 3 is composed of an anchor trench/berm at an elevation of approximately 96 feet NGVD. Module 4 was constructed in 2003, excavated to a depth of approximately 60 ft NGVD. This Module is also provided with a 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 Modules 3 and 4 is an anchor trench/berm, raised approximately three feet above the surrounding surfaces. COMPLIANCE HISTORY SUMMARY The groundwater wells at the North County Landfill did not indicate impact until three VOCs were confirmed at 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. This request was not granted by that property owner. County staff therefore proposed 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 scheduled for installation in 2003 with Module 4. Under Evaluation Monitoring, groundwater and soil gas were sampled quarterly (the WDRs require semi-annual North County RCSL 2 Public Works/Solid Waste 1st Semester 2006 Groundwater Monitoring County of San Joaquin—July 31,2006