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levels near the Site. Data from the fall of 2017 and the spring of 2018 were the most recent available from this source. The Site is just beyond the mapped area (Plates 4 and 5); the closest ground-water contours are zero to ten feet below mean sea level. The ground-water gradient beneath the Site could not be calculated. Given that the ground elevation of the Site is approximately 10 feet above mean sea level, extrapolation would suggest a depth to water of 10 to 20 feet below ground surface in the area. It is anticipated that water levels beneath the Site will fluctuate, especially on a seasonal basis, depending on pumping practices in the area. According to the State Water Resources Control Board's Revised USTCF 5-Year Review Summary, 3rd Review for the Site (2009), ground-water levels beneath the Site fluctuate from 8.6 to 16.5 feet below ground surface, and ground water flows down to the north-northeast. 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. Two common ground-water contaminants in San Joaquin County are nitrate and dibromochloropropane (DBCP). 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 (Plates 6 and 7). According to the nitrate map, two wells within a one-mile radius of the subject Site have been tested for nitrate. One of these wells was found to contain nitrate at a concentration between 0.1 and 5.0 mg/L-N; no nitrate was detected in the other well. According to the DBCP map, one well within a one-mile radius of the Site has been tested for DBCP; no DBCP was detected. The Site is a closed Leaking Underground Storage Tank (LUST) case known as the "Former Gardner Property." According to a Closure Summary Report by Advanced GeoEnvironmental (2009), three gasoline underground storage tanks (USTs) were removed from a service station on the Site in 1989, and soil contamination was identified in the tank excavation. Three ground-water monitoring wells were installed in 1990; gasoline and benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds were detected in the water samples collected; other related compounds were detected in later sampling. Approximately 1,400 cubic yards of soil were excavated from the former UST area in 1995, though impacted soil remained at depths between 11 and 30 feet below ground surface; the excavation was backfilled with clean soil. Advanced GeoEnvironmental estimated that 0.24 pounds of dissolved total petroleum LOGE 2130 Page 3