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15999 W CORRAL HOLLOW RD Project No.2019-00027 Page 18 A groundwater sample was obtained from a nearby building well source.The sample was obtained from a spigot attached to the building,which was verified to connect to the source well. The sample location is shown on Appendix A,Plate 2. The samples were analyzed for nitrate as nitrogen,nitrate,nitrite,and DBCP. The sample for nitrate was collected in a sterile plastic container; the sample for DBCP was collected in two sterile glass vials. The samples were then transported on ice and released under chain of custody to McCampbell Analytical in Pittsburg,California. DBCP was not detected in the water sample. Nitrogen,nitrate,and nitrite were also non-detect,and therefore below the MCL of 10 mg/L set by the United States Environmental Protection Agency(EPA) and State of California. The analytical reports prepared by McCampbell Analytical are attached in Appendix B. Nitrate in groundwater is attributed to the application of fertilizers,livestock,and untreated septic tank waste.Nitrate is mobile and often accumulates in the shallow ground water zones.The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County and other parts of the Central Valley. DBCP was not detected in the water sample taken. DBCP is a soil fumigant and nematocide used in the past for crops. It is thought to cause health problems consisting of kidney damage,liver damage, and cancer. The use of DBCP was discontinued in 1979.The Environmental Protection Agency(EPA) set the maximum contaminant limit(MCL) at 0.2 parts per billion (ppb) because the EPA believes that given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. 5.0 GEOLOGIC AND SOIL PROFILE INFORMATION The Site is depicted on the Geologic Map of the Midway&Tracy quadrangles,Alameda&San Joaquin Counties,and falls within the upper portion of the Neroly Formation(Tn).Tn is characterized by non- marine clastic,thick bedded,medium grained lithified deposits,Miocene in age(Plate 6,Appendix A). The surface and near surface soils located at the Site are reported by the San Joaquin County Soil Survey to be comprised of the Wisflat(35%)-Arburua(30%)-San Timoteo(20%)Complex(Map Unit 275) with other minor components comprising the remaining 15 percent. The Wisflat soil is comprised of sandy,sandy-gravelly loam with 30-50%slopes.The Arburua soil is comprised of loam derived from weathered calcareous sandstone with 30-50% slopes. The San Timoteo soil is comprised of sandy loam with 30-50%slopes and is derived from weathered calcareous sandstone. (Plate 7, Appendix A) (USDA, 1992). The table below presents some selected properties of the individual soil types: I I Petralogix Engineering,Inc. 26675 Bruella Road,Galt,Ca 95632 (209)-400-5729 www.petralogix.com