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Soil Suitability Study Irerracon Flag City#4 Lodi, California February 14, 2019 Terracon Project No. NA187043 Water Resources (DWR) Water Data Library, between the years 1989 and 2013, depth to groundwater measured between approximately 14 to 28 feet bgs at a groundwater well located approximately one quarter mile south of the site. Based on a review of the Lines of Equal Elevation of Groundwater maps available on the SJCFCWCD website, between 2015 and 2016 groundwater flow appeared to have a southerly direction; however, the groundwater flow direction and the depth to shallow, unconfined groundwater, if present, would likely vary 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. 4,2 Potential Groundwater Contamination Issues Identifying potential groundwater contamination sources was not part of the scope of work for the SSS. Potential groundwater contamination can occur from a number of sources including historical petroleum hyrdrocarbon 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. 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 mg/L-NO3 (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 is a nematicide 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 the historical information, agricultural land use and septic systems in the area should be considered potential groundwater contamination sources. Refer to Section 4.4 for further discussion. 4,3 Water Sample Location One groundwater well is currently located on the northern portion of the site. It is our understanding the groundwater well is intended to be used for the proposed development. Refer to Section 4.4 for further discussion. Responsive ■ Resourceful ■ Reliable 7