Laserfiche WebLink
Discussion of Nitrate Loading Results <br /> Total Nitrate Impact <br /> Based on the methods and assumptions described, the result of the nitrate loading <br /> estimate indicates that the proposed development on the Site has the potential to cause <br /> a buildup of nitrate in the aquifer slightly over the MCL of 10 mg/L-N. <br /> There are several mitigating factors that should be considered, however, when <br /> evaluating the 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 /> • The calculated exceedance of 0.9 mg/L-N over the MCL is well within the margin <br /> of error of the nitrate loading calculation. <br /> • Nitrate was not detected in the on-site domestic well, despite the presence of an <br /> existing home on the Site. Based on the map reviewed, none of the five wells <br /> tested for nitrate within one mile of the Site were found to have concentrations <br /> exceeding the MCL. <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. <br /> Taking these factors into account, the actual nitrate loading experienced on the Site <br /> over time may be significantly less than predicted. <br /> LOGE 2606 Page 13 <br />