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LOGE 1903: Coldani NLS Addendum Page 2 <br /> March 21, 2019 <br /> The following table presents a summary of the assumptions for, and results of, the <br /> nitrate loading calculation for the Site when recharge is derived by the <br /> evapotranspiration reduction method with CIMIS data. A modified version of this <br /> method is currently being developed by the San Joaquin County Environmental Health <br /> Department for use in future studies. Details of the calculation are presented in Plate 2. <br /> Table 1. Inputs and Results for Nitrate Loading Calculation, <br /> Recharge Derived from Evapotranspiration Reduction Method <br /> Variable Value Units Description <br /> Q 137.6 gpd Effluent flow rate <br /> Nw 85 mg/L-N Effluent stream concentration <br /> A 10.31 acres Site area <br /> Nb 1.00 mg/L-N Concentration of rain <br /> d 0.25 constant Denitrification factor <br /> R 12.60 inches per year Recharge rate of rainfall <br /> W 0.2 inches per year Uniform waste water loading (calculated) <br /> Nc 1.9 mg/L-N Long-term average concentration of percolating <br /> effluent <br /> For this Site, the long-term average concentration of percolating effluent is found to be <br /> 1.9 mg/L-N when calculated as shown. This value is well below the US EPA <br /> recommended MCL for nitrate in drinking water of 10 mg/L-N. <br /> Although nitrate was detected above the Maximum Contaminant Level (MCL) in the <br /> water sample collected from the domestic well, this impact most likely derives from the <br /> dairy located approximately 900 feet east of the Site, as well as the wastewater <br /> treatment facility located approximately 2,500-feet south of the Site. With the exception <br /> of these two facilities, the surrounding area is largely agricultural. <br />