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Discussion of Nitrate Loading Results <br /> Total Nitrate Impact <br /> Based on the method and assumptions described, the result of the nitrate loading <br /> estimate indicates that a two-bedroom house on the Site has the potential to cause a <br /> buildup of nitrates in the aquifer slightly above 10 mg/L-N; a three- or four-bedroom <br /> house may cause a greater buildup. <br /> There are several mitigating factors that should be considered, however, when <br /> evaluating whether or not this Site is likely to impact ground water with nitrate: <br /> • The Hantzsche and Finnemore equation is a conservative method for <br /> determining potential impacts, and actual nitrate loading experienced on the Site <br /> over time may be less than predicted. 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 /> • According to the map reviewed, several wells in the area have been tested for <br /> nitrate; none are exhibiting nitrate levels above 5 mg/L-N. The test results may <br /> indicate that residential development in the area is not adversely impacting water <br /> quality. <br /> • Based on the clay soil type present on the Site, it is likely that adsorption of <br /> nitrate ions to clay will occur as percolating effluent travels downward through the <br /> vadose zone. True nitrate reduction may exceed that accounted for by the soil <br /> denitrification factor included in the calculation. <br /> • Mr. Kumar has indicated that the area will be connected to municipal sewer <br /> services at some point in the future. The sewer connection will mitigate long- <br /> term impacts from development. <br /> Because of these factors, Live Oak recommends that development of a two-bedroom <br /> house be allowed with a standard septic system utilizing leach lines or a filter bed. If a <br /> three- or four-bedroom house is desired, it is anticipated that the San Joaquin County <br /> Environmental Health Department may request septic system modification for nitrate <br /> reduction. <br /> LOGE 1910 Page 12 <br />