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10 Septic Permit History in the Vicinity Based on a review of septic permits on file at the San Joaquin County Environmental Health Department for nearby properties, it appears that most septic systems in the area utilize leach lines with sumps or 12- to 14-foot deep seepage pits; two permits indicated systems with 25-foot deep seepage pits. The septic permits can be found in Appendix 4 of this report. Expected On-Site Maximum Septic Tank Usage Maximum expected septic usage on the Site would be from the existing home, a theoretical second unit dwelling on Parcel 1, and theoretical primary and secondary dwellings on Parcels 2, 3, and 4. No new construction is proposed. 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 the spring and fall of 2016 were the most recent available from this source (Plates 5 and 6). According to an analysis of these maps, the ground-water elevation is approximately 0 to 20 feet above mean sea level; the ground- water flow is to the northwest at a rate of approximately 14 to 17 feet per mile. Given that the ground elevation of the Site is approximately 115 feet above sea level, based on the County ground water maps the depth to ground water below the Site is estimated to range between 95 to 115 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 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). Four wells were identified at addresses within approximately one mile of the subject Site. Three of the wells had been tested for DBCP; it was not detected in any of the three. All the wells had been tested for nitrate; it was detected in three of the wells at concentrations of 11.8 to 14.9 mg/L-NO3 (equivalent to 2.6 to 3.3 mg/L-N) 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 1834 Page 3