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• Mass Transport Soil Properties The soil type will allow some infiltration of water through the surface soils. The longer the effluent remains near the surface, the more biologic treatment may occur. In a situation where permeable soils exist to the depth of the aquifer, it is possible that any remaining surface contaminants may be transported to the first saturated zone of the aquifer. Groundwater Analysis Depth and Gradient Live Oak reviewed ground-water elevation information available from the San Joaquin County Flood Control and Water Conservation District to determine the ground-water levels near the Site. Data from the spring and fall of 2016 were the most recent available from this source (Plates 6 and 7). According to an analysis of these maps, the ground-water elevation in the area ranges from 28 to 37 feet below mean sea level, depending on the season; the ground-water flow is to the east-northeast at a rate of eight to nine feet per mile. • Given that the ground elevation of the Site is approximately 55 feet above sea level, based on the County ground water maps the depth to ground water below the Site is estimated to range from 83 to 92 feet below ground surface. Potential Ground Water Contamination Issues The Nitrate Loading Study is not intended to be an investigation into ground-water contamination sources, and no such investigation was conducted. Many sources can contribute to ground water contamination, including leaking underground storage tanks, agricultural activities, dairies and cattle ranches, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known ground-water contamination sources with the potential to impact the Site. Live Oak reviewed the San Joaquin County Environmental Health Department's Water Well Data Table dated March 10, 2009 for nearby addresses that have been tested for nitrate and dibromochloropropane (DBCP). Nine wells were identified in a search of addresses within approximately one-half mile of the subject Site. All of the wells had been tested for nitrate; it was detected in seven of the wells at concentrations ranging from 0.2 to 35.0 mg/L-NO3, in one well at a concentration of 64.0 mg/L, and it was not detected in the final well. Eight of the wells had been tested for DBCP; it was not detected in any of the samples. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate as NO3 is 45 mg/L (10 mg/L-N). The MCL for DBCP is 0.2 µg/L. • LOGE 1821 Page 3