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Soil Suitability/ Nitrate Loading Study <br /> Schuler Property . Tracy, California Irerracon <br /> May 30, 2019 Terracon Project No. NA197026 <br /> hydrogeological features. Without the benefit of on-site groundwater monitoring wells surveyed to <br /> a datum, groundwater depth and flow direction beneath the site cannot be directly ascertained. <br /> 1.4.2 Potential Groundwater Contamination Issues <br /> Potential groundwater contamination can occur from a number of sources including historical <br /> petroleum hydrocarbon use, agricultural activities, dairies, septic systems, and storm water <br /> infiltration. As per EHD requirements nitrate as N and 1,2-dibromo-3-chloropropane (DBCP)have <br /> been included as part of the SSS discussion. Identifying potential groundwater contamination <br /> other than nitrates and DBCP is beyond the scope of work for this report. <br /> The presence of nitrates is not uncommon in shallow groundwater aquifers in San Joaquin County <br /> and other parts of the Central Valley. Nitrate in groundwater occurs as a result of the application <br /> of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is mobile and often <br /> accumulates in the shallow groundwater zones. <br /> In the early 1900s, natural levels of nitrate in groundwater were measured in forty-three (43)wells <br /> throughout the Sacramento Valley by Kirk Bryan (1923). It was thought that groundwater at that <br /> time was close to "natural' conditions. Based on the work by Bryan, it is estimated that under <br /> "natural" conditions, groundwater concentration containing nitrate is no more than about 13.5 <br /> milligrams per liter (mg/L) nitrate (NO3) or (3 mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L- <br /> N) or more are those in which nitrate concentrations may be increasing (Hull, 1984). <br /> DBCP (dibromochloropropane) is a nematocide and soil fumigant for vegetables and grapes. It <br /> is thought to cause health problems consisting of kidney damage, liver damage, and cancer. The <br /> use of DBCP was discontinued in 1979. <br /> Based on a review of the Regional Water Quality Control Board GAMA website, nitrate impacted <br /> wells were not identified on the site or in the vicinity. Based on the historical information, the past <br /> agricultural land use and septic systems in the area should be considered potential groundwater <br /> contamination sources. <br /> 1.4.3 Water Sample Location <br /> A groundwater sample was collected from a faucet located east of the existing vacant mobile <br /> home and northwest of the existing barn. <br /> 1.4.4 Groundwater Sample Analysis <br /> On May 10, 2019 two groundwater samples (GW-1 and GW-2) were collected from an exterior <br /> faucet connected to the onsite groundwater well and submitted on ice to McCampbell Analytical <br /> Inc. for analysis. Sample GW-1 was collected into a clean unpreserved plastic 125 milliliter (ml) <br /> bottle and analyzed for nitrate as N by EPA Extraction Method E300.1. Sample GW-2 was <br /> Responsive ■ Resourceful ■ Reliable 7 <br />