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Soil Suitability Nitrate Loading Study l��rracon Recreation Vehicle Service Facility ■ Lockeford, CA April 12, 2017 ■ Terracon Project No. NA177006 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 67,) considered potential groundwater contamination sources. The concerns for groundwater contamination in this area are deemed low to moderate due to the anticipated depth to groundwater of 100 to 120 feet bgs. 1.4.3 Water Sample Location The groundwater well located on the site was not in operation at the time of the report therefore a water sample could not be obtained from the site. Terracon spoke with Mr. Steven Shih of the EHD on March 29, 2017 who indicated a water sample could be collected from the adjoining properties. Ms. Angela (last name not disclosed), resident of the adjoining southern property �3� address of 12008 E. Brandt Road granted Terracon permission to collect water samples from her property. A groundwater sample was collected from a faucet located west of the residence. Refer to Plate 2 for the groundwater well location. 1.4.4 Groundwater Sample Analysis Groundwater sample W1 was analyzed for Nitrate as N by EPA method 300 with laboratory results reported in milligrams per liter (mg/Q. Groundwater sample W2 was analyzed for 1,2-dibromo- 61 LO 3-chloropropane (DBCP) and 1,2-dibromoethane (EDB) by EPA method 82606 with results reported in micrograms per liter(ug/L). The following table summarizes the laboratory results: Responsive■ Resourceful ■ Reliable 7