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the aquifer up to 10.7 mg/L-N for two homes. Adding an accessory dwelling unit raises <br />the calculated buildup of nitrates to 12.7 mg/L-N. <br />The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. The results <br />of the nitrate loading calculations exceed the maximum drinking water standard. <br />Discussion of Nitrate Loading Results <br />Total Nitrate Impact <br />Based on the method and assumptions described, the results of the nitrate loading <br />estimates indicate that the existing and proposed development on the Site have the <br />potential to cause a buildup of nitrate in the aquifer over 10 mg/L-N. <br />It should be remembered, however, that the Hantzsche and Finnemore equation is a <br />conservative method for determining potential impacts, and actual nitrate loading <br />experienced on the Site over time may be less than predicted. The requirement by San <br />Joaquin County Environmental Health Department that the calculation use rainfall and <br />evapotranspiration data to determine ground -water recharge is particularly conservative, <br />as it does not include consideration of recharge from irrigation water or surface water <br />sources. <br />Although Live Oak cannot make engineering recommendations, we are aware that the <br />San Joaquin County Environmental Health Department typically allows the use of <br />standard systems with oversized septic tanks in cases where a 30 percent reduction <br />would bring the nitrate loading under the MCL; the subject Site's nitrate loading result <br />meets this criterion. The use of shallow septic leach fields rather than deeper sumps is <br />anticipated to provide additional reduction in nitrate loading. <br />LOGE 2234 Page 13 <br />