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Soil Suitability / Nitrate Loading Study Azevedo Property Acampo, CA June 19, 2019 Terracon Project No. NA197009 lierracon depending upon seasonal variations in rainfall and other 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 V117 13`) Potential groundwater contamination can occur from a number of sources including historical petroleum hydrocarbon use, agricultural activities, dairies, septic systems, and storm water infiltration. As per EHD requirements nitrate as N and 1,2-dibromo-3-chloropropane (DBCP) have been included as part of the SSS discussion. Identifying potential groundwater contamination other than nitrates and DBCP is beyond the scope of work for this report. 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 milligrams per liter (mg/L) nitrate (NO3 ) or (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 nennatocide 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. Based on a review of the DWR Water Data Library, from the 1950s to 1970s three groundwater wells are located within 0.75 miles northwest and northeast of the site, were analyzed for various constituents including nitrate. Dissolved nitrate was reported in the wells between approximately 5 and 18 mg/L below the EPA MCL of 45 mg/L for nitrate. Copies of the DWR records are included in Appendix D. Based on a review of the State Water Resources Control Board online map, there were no nitrate impacted wells identified near the site. Based on the historical information, the past agricultural land use and septic systems in the area should be considered potential groundwater contamination sources. Refer to Section 1.3.2 for further discussion for information regarding the site groundwater well. 1.4.3 Water Sample Location On April 17, 2019, two groundwater samples (GW-1 and GW-2) were collected from a faucet directly attached to the groundwater well and submitted on ice to McCampbell Analytical Inc. for Responsive Resourceful Reliable 7