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Nitrate Loading Study <br />Nielsen Property Ripon, California <br />January 15, 2019 Terracon Project No. NA187066 <br />lierracon <br />Table 4. <br />Summary of Nitrate Mass Balance Equation. <br />Land Use <br />Result <br />(Nc)* <br />(mg/L- <br />N) <br />Acres (A) <br />Average <br />Daily Flow <br />(Q) (gpd) <br />Effluent <br />Concentration <br />(Nw) <br />(mg/L-N) <br />Leachfield <br />Denitrification <br />(d) <br />Deep <br />Percolation <br />of Rainfall <br />(R) (in) <br />Proposed <br />residential use 20 1.79 560 35 10% 2.54 <br />* EPA maximum contaminant level (MCL) for nitrate as N in drinking water is 10 mg/L-N. <br />Based on the nitrate loading balance calculation (Table 4), nitrate levels for the proposed future <br />use is anticipated to be 20.0 mg/L-N which is above the MCL of 10.0 mg/L-N. <br />3.5.3 Impact of Nitrate Loading to Nearby Water Sources <br />Based on a review of the USGS Avena (1994) California Quadrangle topographic map (Appendix <br />A), the site is located at approximately 80 feet above mean sea level with a topographic gradient <br />toward the west. The nearest surface water source to the site is an unidentified irrigation canal <br />located approximately 1,000 feet southwest of the site. As the subject property is relatively flat, <br />we do not foresee percolating effluent affecting the surface water resources. <br /> <br />4.0 DISCUSSION OF NITRATE LOADING RESULTS RELATIVE TO PROPOSED <br />METHOD OF WASTEWATER DISPOSAL <br /> <br />4.1 Total Nitrate Impact <br />Based on the method and assumptions described, the result of the nitrate loading balance <br />indicates that the proposed residential use on the site may cause a buildup of nitrates (20.0 mg/L- <br />N) in the aquifer above the MCL of 10 mg/L-N. <br /> <br />4.2 Methods of Mitigation <br />Mitigation may consist of the utilization of an advanced water treatment product such as those <br />available by Orenco, which are specifically designed to lower nitrates at point of discharge. Other <br />mitigation options include the use of a carbon source such wood chips. Based on the proposed <br />usage, mitigation may be required by the EHD. <br /> <br />5.0 CONCLUSIONS AND RECOMMENDATIONS <br />The proposed residential use has the potential to cause a buildup of nitrates (20.0 mg/L-N) above <br />the MCL of 10 mg/L-N when an average double occupancy is calculated per bedroom. A <br />groundwater well is not located on the site; therefore, a groundwater sample was not collected. <br />Elevated nitrate levels (up to 70.4 mg/L-N) were reported in off-site groundwater wells located <br />Responsive • Resourceful • Reliable 8