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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Pickens Property■ Tracy, California <br /> May 12, 2020 ■ Terracon Project No. NA207032 <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 (dibromo chloropropane) 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 the historical information, the past agricultural land use, former onsite septic system, <br /> and septic systems in the area should be considered potential groundwater contamination <br /> sources. According to the State Water Resources Control Board website, there were no nitrate <br /> impacted wells reported within 2,000 feet of the site. <br /> 1.4.3 Water Sample Location <br /> A domestic groundwater well is currently located east of the existing residence (Exhibit 2). On <br /> April 14, 2020 two groundwater samples (GW-1 and GW-2) were collected directly from a water <br /> faucet located near the garage (See Exhibit 2). The water faucet was allowed to run for <br /> approxiametly 10 minutes until the well pump turned on and cycled multiple times. <br /> 1.4.4 Groundwater Sample Analysis <br /> Sample GW-1 was collected into a clean unpreserved plastic 125 milliliter(ml) bottle and analyzed <br /> for nitrate as N by EPA Extraction Method E300.1. Sample GW-2 was collected into two clean <br /> glass 40 ml VOAs preserved with ascorbic and meleic acid and analyzed for DBCP (1,2-Dibromo- <br /> 3-chloropropane) by EPA Extraction Method E524.3. <br /> 1.4.5 Groundwater Sample Handling <br /> The groundwater samples were immediately placed on ice and submitted to M_cCamebell �L�N <br /> Anal ical._ln — for analysis. Nitrate as N was reported at',14 milligrams per liter (mg/L)1 in N S <br /> groundwater sample GW-1 slightly above the MCL of 10 mg/L-N. Groundwater sample GW-2 <br /> reported below laboratory reporting limits of 0.010 micrograms per liter(ug/L) for DBCP. <br /> 1.5 Soil Profile and Geologic Information <br /> The site is depicted on the Geologic Map of California 2010, as within generalized quaternary <br /> Pleistocene and Holocene deposits which are comprised primarily of unconsolidated and semi- <br /> consolidated alluvium, lake, playa, and terrace deposits. <br /> Responsive ■ Resourceful ■ Reliable 8 <br />