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26440,8875,&8925 Thornton Road Project No.2017-00010 Page 14 <br /> (msl) to 4.94 msl, respectively..According to the water data library, Well ID 04NO5E03DO03, <br /> labeled as an irrigation well and located approximately 1,800 feet north of the site (parcel <br /> 8925 W. Thornton Road) has groundwater elevation ranging from -3.36 msl to 5.64 msl, or <br /> 12 feet to 3 feet bgs, respectively,based on fall and spring measurements from 1987 to 2010. <br /> DWR's GeoTracker$ website was additionally reviewed for potential groundwater <br /> information. A closed Leaking_Underground Storage Tank (LUST) clean-up site, RB_Case <br /> Number 390193 is located at 8960 Walnut Grove Road, approximately 50 feet due south of <br /> the site. According to the Case Closure Summary, dated April 28, 2004, depth to <br /> groundwater, as measured from seven (7) groundwater monitoring wells onsite, had a high <br /> groundwater depth of 5 feet bgs and a low groundwater depth of 9 feet bgs. The flow <br /> direction was reportedly west/southwest.A review of the monitoring well data provided for <br /> each well point on GeoTracker indicates the wells were measured each September, from <br /> 2001 to 2003. <br /> The nearest depth to groundwater data for the site is reported for the previously discussed <br /> LUST Case Closure Summary RB Case Number 390193 on the parcel located approximately <br /> 50 feet due south of the Site at 8960 W.Walnut Grove. In addition to being in close proximity <br /> to the site, the site has similar ground surface elevations, ranging from 10 to 15 feet msl. <br /> Based on this information, the site is estimated to have a depth to groundwater of <br /> approximately 5 to 9 feet bgs and a flow direction of west/southwest. Based on the lack of <br /> data for the area, a gradient has not been determined, although it is anticipated to be a <br /> shallow based on the relatively flat topography. <br /> 3.2 Potential Groundwater Contamination Issues <br /> The site is located within a small urban mixed commercial-residential community and near <br /> parcels involved in agricultural practices; 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 /> 3.3 Current and Future On-Site Groundwater Uses <br /> The use of public water for drinking water provided by the San Joaquin County Maintenance <br /> District is planned for the proposed development!There are currently no wells on the site. <br /> 4.0 SOURCES AND IMPACT OF NITRATE TO GROUNDWATER <br /> 4.1 Current Off-Site Sources of Nitrate <br /> Septic systems and agriculture in the area may be the most significant sources of nitrate. In <br /> an attempt to determine the septic system density for the vicinity of the site, our office <br /> 8 http://Peotracker.waterboards.ca.gov/Accessed November 18, 2017. <br /> Petralogix Engineering,Inc. <br /> 26675 Bruella Road,Galt,Ca 95632 <br /> (209)A00-5729 <br /> www.petralogixcom <br />