Laserfiche WebLink
Table 4. Assumptions for Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Q 7,095 gpd Effluent flow rate <br /> Nw 85 mg/L-N Effluent stream concentration <br /> A 9.49 acres Site area <br /> Nb 0.3 mg/L-N Concentration of rainwater <br /> d 0.35 constant Denitrification factor <br /> R 3.00 inches per year Deep percolation of rain <br /> W 10.1 inches per year Uniform waste water loading (calculated) <br /> The details of the nitrate loading calculation are included in Plate 15. The results of the <br /> calculation are presented in the following table. <br /> Table 5. Result of Nitrate Loading Calculation <br /> Variable Value Units Description <br /> Nc 42.6 mg/L-N Long-term average concentration of percolating effluent <br /> The US EPA recommended MCL for nitrate in drinking water is 10 mg/L-N. In a worst- <br /> case situation, the maximum buildup of nitrates in the aquifer from the use of septic <br /> systems on the Site is predicted to be 42.6 mg/L-N. The result of the nitrate loading <br /> estimate exceeds the maximum drinking water standard. <br /> The Hantzsche and Finnemore equation is a conservative method for determining <br /> potential impacts, and actual nitrate loading experienced on the Site over time may be <br /> less than predicted. The requirement by San Joaquin County Environmental Health <br /> Department that the calculation use rainfall and evapotranspiration data to determine <br /> ground-water recharge is particularly conservative, as it does not include consideration <br /> of recharge from irrigation water or surface water sources. <br /> LOGE 1947 Page 13 <br />