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based on the San Joaquin County On-Site Wastewater Treatment Systems Standards (2017) or other engineering recommendations. Ground Water Information 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 spring and fall of 2016 were the most recent available from this source (Plates 6 and 7). The Site is beyond the mapped area for both years; the closest ground-water contours are at ten feet below sea level. The ground-water flow direction and gradient could not be calculated. Ground water depth and flow direction in the Delta islands is highly dependent on seasonal pumping and irrigation in the area. No ground water was encountered by Live Oak during the drilling of the shallow percolation test boring discussed later in this report. Given that the ground elevation of the Site is approximately five feet above sea level, based on the maps reviewed and projection of the mapped ground-water contours, the depth to water below the Site is estimated to be less than 15 feet. Potential Ground Water Contamination Issues The Soil Suitability 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, 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 maps of Nitrate - Land Use Data and DBCP - Land Use Data dated February 20, 2019. According to the maps, no wells in the immediate vicinity of the Site have been tested for either constituent. The closest wells are approximately two miles from the Site. As the nitrate map shows (Plate 8), six wells within two miles of the Site were tested for nitrate; nitrate was detected in four of the wells at a concentration between 0.1 and 5.0 mg/L-N; no nitrate was detected in the remaining two wells. As depicted on the DBCP map (Plate 9), four wells within two miles of the Site were tested; no DBCP was detected in any of the wells. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 ug/L. The surrounding area consists of agricultural land and orchards with occasional rural residences and agricultural buildings. LOGE 20-17 Page 3