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The longer the effluent remains near the surface, the more biologic treatment may <br /> occur. In a situation where permeable soils exist to the depth of the aquifer, it is possible <br /> that any remaining surface contaminants may be transported to the first saturated zone <br /> of the aquifer. <br /> Groundwater Analysis <br /> Depth and Gradient <br /> Live Oak reviewed ground-water elevation information available from the San Joaquin <br /> County Flood Control and Water Conservation District to determine the ground-water <br /> levels near the Site. Data from the spring and fall of 2016 were the most recent <br /> available from this source (Plates 6 and 7). According to an analysis of these maps, the <br /> ground-water elevation in the area is approximately one foot above to 20 feet below <br /> mean sea level. The ground-water flow direction is uncertain for spring; for fall the flow <br /> is to the northeast at a rate of approximately 20 feet per mile. <br /> Given that the ground elevation of the Site is approximately 100 to 105 feet above sea <br /> level, based on the County ground water maps the depth to ground water below the Site <br /> is estimated to be 99 to 125 feet below ground surface. <br /> Potential Ground Water Contamination Issues <br /> The Nitrate Loading Study is not intended to be an investigation into ground-water <br /> contamination sources, and no such investigation was conducted. Many sources can <br /> contribute to ground water contamination, including leaking underground storage tanks, <br /> agricultural activities, dairies and cattle ranches, septic systems, and storm water <br /> infiltration. Agricultural activities and the use of septic systems in the area are known <br /> ground-water contamination sources with the potential to impact the Site. <br /> Live Oak reviewed the San Joaquin County Environmental Health Department's Water <br /> Well Data Table dated March 10, 2009 for nearby addresses that have been tested for <br /> nitrate and dibromochloropropane (DBCP). Only one well was identified in a search of <br /> addresses within approximately one mile of the subject Site. Nitrate was detected at a <br /> concentration from of 88 mg/L-NO3 (19.6 mg/L-N) in the sample; DBCP was not <br /> detected. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate as <br /> NO3 is 45 mg/L (10 mg/L-N). The MCL for DBCP is 0.2 ug/L. <br /> LOGE 1840 Page 3 <br />