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There are several factors that should be considered, however, when evaluating the <br /> degree to which the Site is likely to impact ground water with nitrate: <br /> • The Hantzsche and Finnemore equation is a conservative method for <br /> determining potential impacts. The requirement by San Joaquin County <br /> Environmental Health Department that the calculation use rainfall and <br /> evapotranspiration data to determine ground-water recharge is particularly <br /> conservative, as it does not include consideration of recharge from irrigation <br /> water or surface water sources. <br /> • Depth to ground water beneath the Site is estimated to be approximately 58 feet, <br /> and only shallow septic systems are typically permitted in this area. Given these <br /> conditions, the vadose zone of the new, shallow septic system will be at least 48 <br /> feet, and significant nitrate attenuation may take place over the course of this <br /> span. Selection of leach lines or a filter bed septic system, rather than leach <br /> lines with sumps, would increase the vadose zone. <br /> • Nitrate was detected at 18.8 mg/L-N, significantly over the MCL, in the on-site <br /> domestic well. Based on the sparse residential development in the area, it <br /> appears that fertilization of the surrounding orchards may be a major contributing <br /> factor to the elevated nitrate level. <br /> LOGE 2619 Page 14 <br />