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• Given that the ground elevation of the Site is approximately 25 to 35 feet, the depth to water below the Site is estimated to be 24 to 43 feet, depending on the location on the Site. 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. According to the State Water Resources Control Board's GeoTracker website, Delicato Vineyards is the site of a leaking underground storage tank case. The leak reportedly affected soil only, and the case was closed in 1997. Delicato Vineyards is also required by the California Regional Water Quality Control Board (Regional Board) to participate in a Monitoring and Reporting Program, which includes sample collection at the wastewater ponds and land application area, as well as ground water sampling from six monitoring wells. One of the constituents for which the ground water samples are analyzed is nitrate. According to the Waste Discharge • Requirements issued by the Regional Board (2013), values of nitrate as nitrogen in the monitoring wells have ranged from 1 to 32 mg/L between 2001 and 2012; the EPA's Maximum Contaminant Level (MCL) is 10 mg/L. Other waste water-related constituents have also been detected in the monitoring wells. Live Oak reviewed the EHD's Water Well Data Table dated March 10, 2009 for nearby addresses that have been tested for nitrate and dibromochloropropane (DBCP), common ground-water contaminants in San Joaquin County. A total of 11 wells were identified within approximately one mile of the Site. All but one of the wells were analyzed for nitrate; nitrate as NO3 was detected in all 10 wells tested at concentrations from 3.4 to 96.0 mg/L. All but two of the wells had been tested for DBCP; it was detected in only one of the nine wells tested, at a concentrations of 1.6 µg/L. One of the wells tested was a public water well at the Site address of 12001 S. Highway 99; nitrate was detected in this well at a concentration of 3.4 mg/L-NO3; DBCP was not detected. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate as NO3 is 45 mg/L (equivalent to 10 mg/L-N); the MCL for DBCP is 0.2 µg/L. It appears that nitrate and DBCP are present at levels in excess of the MCL in some ground water in the area. • LOGE 1714 Page 7