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21300 MANN ROAD Project No.2019-00095 Page 14 4.0 GROUNDWATER INFORMATION 4.1 Groundwater Depth and Gradient The San Joaquin County Flood Control and Water Conservation District(2016)groundwater reports were reviewed to determine the groundwater levels near the Site. The Fall 2016 and Spring 2016 maps are the most current official maps available from the County. According to these maps, (Plates 6 and 7) in Appendix A, groundwater elevation lies between -50 and -30 feet below mean sea level (msl)in the spring and fall,respectively. The elevation of the land,as previously mentioned in Section 1.1, is approximately 80 feet above mean sea level. Therefore, the depth to groundwater (the difference between the elevation of the Site and the elevation of groundwater), ranges between approximately 110 and 130 feet below the ground surface (bgs), depending on the season. The groundwater in the vicinity of the Site appears to flow to the west,toward a cone of depression during the spring, and north-northeast toward a cone of depression during the fall, at a gradient of approximately 10 feet per mile. No groundwater was encountered by the staff of Petralogix, Inc. during the percolation test hole auguring on November 1,2019. 4.2 Potential Groundwater Contamination Issues No above- or below-ground off-site potential or known sources of contamination were identified from current uses of the surrounding properties,except for the following: • Surrounding properties are used for agriculture; agricultural chemicals may be applied to these properties. • The site and surrounding properties utilize septic systems. The site is located within an agricultural region; groundwater contamination can result from activities related to farming practices where chemicals are applied to crops which may permeate to groundwater. The site and surrounding properties utilize septic systems; leakage from septic tanks or failed septic systems can introduce bacteria to groundwater. 4.3 Water Sample Locations and Constituents There is currently one domestic well onsite, however, there was no power to the site at the time of the nitrate loading study,therefore the groundwater at the site was not tested. 4.4 Current and Future On-Site Groundwater Uses The use of ground water for drinking water is planned for the proposed development. There is currently one domestic well onsite, however,at the time of the nitrate loading study/soil suitability study,there was no power to the site,therefore the well was inoperable. Petralogix Engineering,Inc. 26675 Brue Road,Galt,Ca 95632 (209)-400.5729 www.petralogix.com