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30 March 2022 AdvancedGeo <br />Project No. 22-6800 An Employee -Owned Company <br />Page 10 of 15 <br />8.2. EXISTING OR POTENTIAL GROUNDWATER CONTAMINATION <br />The immediately adjacent and outlying land use for the parcel is agricultural and <br />residential. Potential groundwater contamination can occur from several sources <br />including leaking underground storage tanks, septic systems, agricultural activities, <br />dairies, and stormwater infiltration. <br />A review of the DTSC EnviroStor Database and the Geotracker Web site did not reveal <br />any LUST sites within a half -mile radius of the site. The review did not reveal any other <br />sites of environmental concern within a half -mile radius of the site. Based on the <br />information reviewed, there is no existing or known groundwater contamination at the site <br />and the potential for groundwater contamination is de minimis. <br />8.3. CURRENT AND FUTURE USE OF GROUNDWATER AT THE SITE <br />The existing water supply well at 10800 E West Ripon Road (site) conforms to DWR and <br />EHD standards. The well is currently utilized for the potable water source at the property <br />and will continue to be used to supply the subject property with a domestic water source. <br />9.0. IMPACT OF NITRATE TO GROUNDWATER <br />Due to the planned residential use of the property and the potential for nitrate leaching <br />into the groundwater from the proposed septic system, a nitrate loading analysis for the <br />future use of the septic system is required by the EHD. <br />9.1. CURRENT OFF-SITE SOURCES OF NITRATE <br />Septic systems and agriculture are sources of nitrates in the area of the site. The property <br />is bordered by agricultural and residential land, which might provide a nitrate source. <br />There are several residences within 1,000 feet of the site. <br />9.2. IMPACT OF RAINFALL CONTRIBUTION TO NITRATE LOAD <br />The rainfall of the area has been estimated for the nitrate loading analysis. Deep <br />percolation is estimated by calculating the average monthly rainfall and <br />evapotranspiration of the site area. If average monthly rainfall exceeds average monthly <br />potential for evapotranspiration (ETo) there is a potential for deep percolation without <br />consideration for runoff. Average potential ETo was estimated from data obtained from <br />the California Irrigation Management Information System (CIMIS) Ripon Station #249. <br />Ripon Station #249 has been collecting ETo and precipitation data since January 2017. <br />