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Soil Suitability/ Nitrate Loading Study 1��rracon Ripon Winery Proposed Warehouse ■ Ripon, CA January 20, 2017 ■ Terracon Project No. NA167059 gallons per person per day for 30 persons working three 8 hours shifts per day and 16 visitors at 5 gallons per day per person, 5 days per week). 1.4 Groundwater Information 1 .4.1 Groundwater Depth and Gradient Groundwater was not encountered in our percolation test hole excavated to a depth of 36 inches on January 12, 2017. According to the San Joaquin County Flood Control and Water Conservation District Groundwater Report(SJCWCD) Fall 2015, groundwater depth lies between approximately 40 and 50 feet bgs. Based on a review of the SJCWCD Lines of Equal Elevation of Groundwater Fall 2015 map, groundwater flow gradient appears to be in a northerly direction. The groundwater flow direction and the depth to shallow, unconfined groundwater, if present, would likely vary depending upon seasonal variations in rainfall and other hydrogeological features. Without the benefit of on-site groundwater monitoring wells surveyed to a datum, groundwater depth and flow direction beneath the site cannot be directly ascertained. 1.4.2 Potential Groundwater Contamination Issues The presence of nitrates is not uncommon in shallow groundwater aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in groundwater occurs as a result of the application of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is mobile and often accumulates in the shallow groundwater zones. In the early 1900s, natural levels of nitrate in groundwater were measured in forty-three (43)wells throughout the Sacramento Valley by Kirk Bryan (1923). It was thought that groundwater at that time was close to "natural' conditions. Based on the work by Bryan, it is estimated that under "natural" conditions, groundwater concentration containing nitrate is no more than about 13.5 mg/L-NO3 (3 mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate concentrations may be increasing (Hull, 1984). DBCP (dibromochloropropane) is a nematocide and soil fumigant for vegetables and grapes. It is thought to cause health problems consisting of kidney damage, liver damage, and cancer. The use of DBCP was discontinued in 1979. EDB (ethylene dibromide) was used in gasoline to prevent lead deposits and build up. It was also used in pesticides and fumigants. Exposure to EDB is linked to many adverse health effects stemming from organ damage to cancer. Agricultural activities, industrial activities, and the use of septic systems in the area should be considered potential groundwater contamination sources. The concerns for groundwater contamination in this area are deemed low to moderate due to the depth to groundwater of 90 to 100 feet bgs. Responsive■ Resourceful ■ Reliable 7