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NOA Drywell Closure and Investigation Page 4 of 26 <br /> ' May 30, 2014 <br /> 1 Table 1 — Summary of Site-Specific Subsurface Conditions <br /> Summarized from March 28, 2014 and April 1, 2014 Soil Sampling Activities <br /> Depth feet bgs) Description <br /> 0 - 40 Well Casing <br /> 40 - 50 Gravel Pack <br /> ' <br /> 51 - 54 Sand silty, brown fine moist dense <br /> 54 - 58 Sand cleanyellowish brown coarse moist very dense <br /> 58-61 Sand clayey, brownish gray, fine moist very dense <br /> 61 -64 Sand cleangray, coarse moist very dense <br /> 64-75.5 Sand silty, dark gray, fine wet dense <br /> 75.5 - 76.5 Gravel fine poorly sorted dark­gray, wet very dense <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 Regional Hydrogeology <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, depth to <br /> groundwater is 70 feet bgs, and the flow direction is approximately south. According to the San <br /> Joaquin County Flood Control and Water Conservation District Fall 1999 — Spring 2007 <br /> Groundwater Report, groundwater at the subject property in Spring 2004, just after the <br /> installation of the drywells, was also at an elevation of -20 feet bgs, depth to groundwater was <br /> 70 feet bgs, and flow direction was approximately south. <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 0.93 mS/cm Electrical Conductivity (EC) and 595 ppm Total Dissolved Solids <br /> (TDS). According to DWR Water Quality Reports, the pH of groundwater in the region is <br /> between 7.4 and 8.4. <br /> t According to the State Water Resources Control Board 5, the secondary Maximum Contaminant <br /> Level (SMCL) for EC in drinking water is 0.9 mS/cm, the SMCL for pH in drinking water is 6.5 to <br /> 8.5, the SMCL for TDS is 0.5 g/L, and dissolved oxygen should be greater than 3 mg/L. There is <br /> 1 no SMCL for water temperature. Secondary MCLS are non-enforceable drinking water guidelines <br /> for aesthetic considerations. <br /> 1 s Recommended Numerical Limits to Apply Water Quality Objectives, based on A Compilation of Water <br /> Quality Goals, California Regional Water Control Board, Central Valley Region. <br /> 902 Industrial Way• Lodi, CA 95240.209.367.3701 •Fax 209.333.8303 02014 Neil O.Anderson Et Associates,Inc. <br />