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33503 S Koster Road Project No.2021-00073 Page 14 <br /> ground water aquifers. Therefore, soils of this type typically present a low risk of excessive <br /> mass transport of nitrate or other constituents of concern. <br /> 4.0 GROUNDWATER INFORMATION <br /> 4.1 Groundwater Depth and Gradient <br /> The San Joaquin County Flood Control and Water Conservation District (2017 and 2018) <br /> groundwater reports were reviewed to determine the groundwater levels near the Site. The <br /> Fall 2017 and Spring 2018 maps are the most current official maps available from the <br /> County. According to these maps, (Plates 5 and 6) in Appendix A, groundwater elevation is <br /> approximately 45 and 55 feet below mean sea level (msl) in the fall and spring, respectively. <br /> The elevation of the land, as previously mentioned in Section 1.1, is approximately 125 feet <br /> above mean sea level. Therefore, the depth to groundwater (the difference between the <br /> elevation of the Site and the elevation of groundwater), is approximately 80 and 70 feet <br /> below the ground surface (bgs) in the fall and spring, respectively. The groundwater in the <br /> vicinity of the Site appears to flow to the northeast, at a gradient of approximately 10 feet <br /> per mile. <br /> No groundwater was encountered by the staff of Petralogix, Inc. during the shallow <br /> percolation test hole auguring on September 6, 2021. <br /> 4.2 Potential Groundwater Contamination Issues <br /> No above- or below-ground off-site potential or known sources of contamination were <br /> identified from current uses of the surrounding properties, except for the following: <br /> • Surrounding properties are used for agriculture; agricultural chemicals may be <br /> applied to these properties. <br /> • The site and surrounding properties utilize septic systems. <br /> The Site is located within an agricultural region; groundwater contamination can result from <br /> activities related to farming practices where chemicals are applied to crops which may <br /> permeate to groundwater. The site and surrounding properties utilize septic systems; <br /> leakage from septic tanks or failed septic systems can introduce bacteria to groundwater. <br /> 4.3 Water Sample Locations and Constituents <br /> A domestic well groundwater sample was obtained from the site on September 7, 2021 by <br /> Tonya Scheftner. Laboratory supplied containers, an ice-chest, ice, chain-of-custody <br /> documentaion, and sampling equipment (plastic gloves, plastic bags) were obtained prior to <br /> sampling. The sample was collected after flushing the system with a reduced steady stream <br /> for a minimum of five minutes. No filtration system was observed or reported. <br /> Petralogix Engineering,InC. <br /> 26675 BruelIa Road,Galt,Ca 95632 <br /> (209)-40o-5729 <br /> www.petralogix.com <br />