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Soil Suitability/Nitrate Loading Study Irerracon <br /> Proposed Commercial Truck Yard ■ Stockton, CA <br /> August 16, 2019 ■ Terracon Project No. NA197053 <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 State Water Resources Control Board online map, there were no nitrate <br /> impacted wells identified near the site. Based on the historical information, the past agricultural <br /> land use and former septic systems on the site should be considered potential groundwater <br /> contamination sources. <br /> 1.4.3 Water Sample Location <br /> A groundwater well is not located on the site, therefore, a groundwater sample was not collected. <br /> 1.4.4 Groundwater Sample Analysis <br /> Refer to Section 1.4.3. <br /> 1.4.5 Groundwater Sample Handling <br /> Refer to Section 1.4.3. <br /> Responsive■ Resourceful ■ Reliable 8 <br />