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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Pickens Property■ Tracy, California <br /> May 12, 2020 ■ Terracon Project No. NA207032 <br /> uses associated with this project. The following table presents a summary of the nitrate loading <br /> calculation for the site. A copy of the nitrate loading calculation is included in Appendix F. <br /> Table 10. <br /> Summary of Nitrate Mass Balance Equation. <br /> Result Average Effluent Leachfield Net Rainfall <br /> Acres Concentration <br /> Land Use (Nc)" Daily Flow Denitrification Charge(R) <br /> (mg/L-N) (A) (Q)(gpd) (Nw) (d) (inlyear) <br /> (mg/L-N) <br /> Existing Residence 11.6 1.10 200 40 35% 3.31 <br /> Existing&Proposed 15.9 1.10 400 40 35% 3.31 <br /> Residence <br /> Total 15.9 <br /> `Maximum contaminant level(MCL)for nitrate in drinking water is 10.0 mg/L-N. <br /> Based on the nitrate loading balance, nitrate levels for the existing residence is 11.6, above the <br /> MCL of 10.0 mg/L-N. The proposed second residence is anticipated to further increase nitrate as <br /> N levels to 15.9 mg/L-N, also above the MCL of 10.0 mg/L-N. <br /> 2.3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> Based on the aerial photographs and topographic maps (Section 1.1), the nearest surface water <br /> source is the Delta Menodota Canal which is located to the adjoining north of the site and elevated <br /> above the site and is not anticipated to be effected by percolating effluent. <br /> 2.4 Discussion of Nitrate Loading Results <br /> 2.4.1 Total Nitrate Impact <br /> Based on the method and assumptions described, the result of the nitrate loading balance (15.9 <br /> mg/L N for both residences) indicates that the development on the parcel may cause a buildup of <br /> nitrates in the aquifer above the MCL of 10.0 mg/L-N. <br /> 2.4.2 Methods of Mitigation <br /> Based on the nitrate loading results, nitrate impacts to groundwater are anticipated; therefore, <br /> mitigation measures may be required for the project. <br /> 3.0 CONCLUSIONS AND RECOMMENDATIONS <br /> Terracons 2018 Percolation Test Letter stated the following: "Based on the results of the field <br /> work, site soils consist primarily of dry clay in the upper 1.8 feet and fine sand to a fine sandy silt <br /> with clay from 1.8 feet to 10 feet bgs. A visual inspection of the soils from the percolation test and <br /> Responsive ■ Resourceful ■ Reliable 16 <br />