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NOA Drywell Closure and Investigation Work Plan Page 4 of 16 <br /> ' March 18, 2014 <br /> Revised March 20, 2014 <br /> 1 The ground surface elevation of the Site is approximately 50 feet above MSL. According to the <br /> California Soil Resource Lab, online soil survey", the subject property is located within a zone <br /> classified as Tokay-Urban land complex. Fifty percent is Tokay, 35 percent is Urban, and 15 <br /> percent are inclusions. The Tokay series includes coarse loam, with 0 to 2 percent slopes, is <br /> well drained, and consists of alluvium derived from granitic rock sources. The landform <br /> classification includes fan skirts and landscape consists of valleys. <br /> 2.5.2 Site-Specific Geology <br /> Site-Specific Geology would be determined by on-site drilling activities during soil sampling. <br /> 2.6 Hydrogeologic Conditions <br /> ' The Site hydrogeologic conditions were obtained from the San Joaquin County Flood Control <br /> and Water Conservation District, the California Department of Water Resources (DWR), and Site <br /> reconnaissance. <br /> 2.6.1 Reoional Hvdrogeoloov <br /> According to the San Joaquin County Flood Control and Water Conservation District Fall 2012 <br /> Groundwater Report, groundwater elevation at the subject property is -20 feet and depth to <br /> groundwater is 70 feet bgs. According to the San Joaquin County Flood Control and Water <br /> Conservation District Fall 1999 — Spring 2007 Groundwater Report, groundwater at the subject <br /> property in Spring 2004, just after the installation of the drywells, was also at an elevation of <br /> -20 feet bgs and depth to groundwater was 70 feet bgs. <br /> According to the San Joaquin County Flood Control and Water Conservation District Fall 2012 <br /> Groundwater Report, groundwater in the nearest northern San Joaquin County groundwater <br /> well contains 23 ppm Chloride, 0.93 EC, and 595 ppm TDS. According to DWR Water Quality <br /> Reports, the pH of groundwater in the region is between 7.4 and 8.4. <br /> 2.6.2 Site-SDecific Hvdrooeologv <br /> Depth to groundwater measurements taken on March 6, 2014, just prior to termination of the <br /> release, indicate that on-site groundwater levels range from 43.34 feet bgs to 45.65 feet bgs. <br /> Groundwater levels are anticipated to drop subsequent to discontinuation of the discharge to <br /> the wells. <br /> °UC Davis California Soil Resources lab,Online Soil Survey, httD7//`casoilresource.lawr.ucdavis.edu/­soilweb/ <br /> 902 Industrial Way•Lodi,CA 95240-209.367.3701•Fax 209.369.4228 02014 Neil O.Anderson&Associates,Inc <br />