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INTRODUCTION General This groundwater monitoring report for the North County Recycling Center and Sanitary Landfill (NCRC&SL) is submitted in compliance with Waste Discharge Requirements (WDR) Order No. R5-2010-0016. The NCRC&SL is located at 17720 East Harney Lane, approximately nine miles east of Lodi (Figure 1). Land uses within 1,000 feet of the facility are primarily agricultural and livestock grazing. The average precipitation near the landfill is 17.5 inches per year. The NCRC&SL is a single solid waste management unit, designated Class III, accepting non- hazardous municipal solid waste and inert waste, as defined in §20164 of Title 27. The site is 185 acres in area, comprised of lined areas (previously designated "modules"), each constructed on an as-needed basis. The total capacity of the landfill is 16.2 million cubic yards. Geology The sediments underlying the Unit consist of inter-bedded sands, silts and clays with occasional gravelly layers. The measured hydraulic conductivity of the unsaturated zone soils underlying the Unit is between 1 x 10-4 and 2 x 10-7 centimeters/second. The first encountered groundwater is 145 to 157 feet below ground surface. Groundwater elevations range from -30 feet -42 National Geodetic Vertical Datum (NGVD), fluctuating seasonally approximately 6 feet. The groundwater is unconfined. Construction Details of construction are contained in the Waste Discharge Requirements for this site. Lined Area 1 (previously designated "Modules 1 and 2") was constructed in 1991. This area was excavated to an elevation of approximately 88 feet NGVD, which is approximately 30 feet below original grade. This Area is provided with a 60-mil HDPE liner installed over a 6-inch (minimum) thick layer of compacted native soil. The unit is not designed to meet Title 27 and RCRA Subtitle D criteria since at the time of constructionthese regulations were not in effect. Lined Area 3 was constructed in 1995, excavated to an elevation of approximately 60 ft NGVD, which is approximately 60 feet below original grade. This Area is provided with a composite liner comprised of a geocomposite clay layer (GCL) under a 60 mil HDPE membrane. This liner design was approved as an engineered alternative to the prescriptive composite liner of Title 27 and RCRA Subtitle D. The interface between Areas 1 and 3 is composed of an anchor trench/berm at an elevation of approximately 96 feet NGVD. Lined Area 4 was constructed in 2003, excavated to a depth of approximately 60 ft NGVD, which is approximately 60 feet below original grade. This Area is also provided with a North County RC&SL Public Works/Solid Waste I"Semiannual 2014 Groundwater Monitoring 1 County of San Joaquin—July 31,2014