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February 24,2020 BGG Job No. G123.02 Expected On-Site Maximum Septic Tank Usage Maximum expected usage for the proposed onsite septic system will be from the future employees at the proposed winery as well as daily visitors and quarterly event patrons. Septic system design should be based on the San Joaquin County On-Site Wastewater Treatment Systems Standards (2017)or other engineering recommendations. GROUNDWATER INFORMATION Groundwater Depth and Gradient We reviewed ground water elevation information available from the California Department of Water Resources Water Data Library (CA WDL) and the San Joaquin County Flood Control and Water Conservation District(SJCFCWCD)to determine the ground water levels near the Site. Recent data indicates that ground water at the site is approximately 70 to 75 feet below ground surface(bgs)and ground water flows predominantly toward the northwest.The property owner recently recorded the groundwater level in the existing onsite irrigation well to be approximately 71 feet bgs.A detailed evaluation of these and other factors,which may be responsible for groundwater fluctuations,was beyond the scope of this study. Potential Ground Water Contamination Issues The Soil Suitability Study is not intended to serve as an investigation into groundwater contamination sources,and no such investigation was conducted. Many sources can contribute to ground water contamination, including underground storage tank leaks, agricultural applications, dairy activities, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known groundwater contamination sources with the potential for impact to the site. BGG reviewed the SJC EHD Water Well Data Table dated March 10,2009 for nearby addresses that have been tested for nitrate and dibromochloropropane (DBCP), identified groundwater contaminants in San Joaquin County. The Maximum Contaminant Level(MCL)established by the US EPA for nitrate as NO3 is 45 mg/L(10 mg/L-N)and the MCL for DBCP is 0.2 pg/L. For wells identified within approximately 1 mile of the subject site, the following summarizes the reported results: • Nitrate was detected in the wells identified, at concentrations of 25.0 to 48.0 mg/L-NO3. • DBCP was not detected. Wells Onsite A domestic well is currently located at the site, northwest of the existing residence, as shown on Plate 2, Site Plan. The existing well is used by the private residence and will not be utilized for the proposed winery improvements. No well permits were identified for the Site from among files at the San Joaquin County Environmental Health Department. Water Sample A water sample was not collected for this study. BAEZ GEOTECHNICAL GROUP Soil Suitability Study and Nitrate Loading Study-Zinc House Winery Page 3