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Soil Suitability/Nitrate Loading Study Irerracon <br /> Soares Property ■ Escalon, CA <br /> December 13, 2019 ■ Terracon Project No. NA197095 <br /> denitrify by about 35 percent, and soils with high sand content and fast percolation rates are <br /> estimated to denitrify at a lower rate, about 10 percent to 15 percent. <br /> Based on the results of the shallow soil borings, the proposed leach field is expected to be located <br /> within sandy silt and sandy clay soils. Based on depth to groundwater and review of the Well <br /> Completion records (Section 1.5.4), a denitrification estimate of 25 percent was selected. <br /> 2.3.5 Nitrate Loading Scenario <br /> A nitrate loading scenario was performed to determine the impact from the proposed project. The <br /> scenario utilizes the variables discussed previously which represent the estimated conditions and <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 11. <br /> Summary of Nitrate Mass Balance Equation. <br /> Result Average Effluent Leachfield Deep <br /> Acres Concentration Percolation <br /> Land Use (Nc)* (A) Daily Flow (Nw) Denitrification of Rainfall <br /> (mg/L-N) (Q)(gpd) (mg/L-N) (d) (R)(in) <br /> Proposed Residence 24.2 0.81 420 45 25% 2.89 <br /> LL L-Maximum contaminant level(MCL)for nitrate in drinking water is 10 mg/L-N. <br /> Based on the nitrate loading balance, nitrate levels for the proposed residence is 24.2 mg/L-N, <br /> 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), no surface water source is <br /> near site. <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 (24.2 <br /> mg/L N) indicates that the development on the parcel may cause a buildup of nitrates in the aquifer <br /> above the MCL of 10 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 /> Responsive ■ Resourceful ■ Reliable 16 <br />