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Soil Suitability/ Nitrate Loading Study <br /> Ernst Property Tracy, CA Irerracon <br /> February 21, 2019 Terracon Project No. NA197000 <br /> percent. Soils with higher clay content, moist soil conditions, high pH, and organic material <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 new leach field is expected to be <br /> located within silty sandy soils with clay below 2.5 feet bgs. Based o the soils encountered <br /> during our borings and anticipated percolation rate, a denitrification stimate of 30 percent was <br /> 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 6. <br /> Summary of Nitrate Mass Balance Equation. <br /> Result Average Effluent Leachfield Deep <br /> Acres Concentration Percolation <br /> Land Use (Nc)* Daily Flow Denitrification <br /> (mg/L-N) (A) (Q)(gpd) (Nw) (d) of Rainfall <br /> (mg/L-N) (R)(in) <br /> Existing Residence 7.2 2.07 700 35 30% 12.78 <br /> Existing Residence 9.5 2.07 1,120 / 35 j 30% 12.78 <br /> and Proposed Mobile / <br /> Home <br /> *Maximum contaminant level(MCL)for nitrate in drinking water is 10 mg/L-N. j 1 �Yi �J , AVI <br /> Qx-r-,rY, (Ao4aP <br /> Based on the nitrate loading balance calculation (Table 6), nitrate levels for the proposed use is <br /> anticipated at 9.5 mg/L N below the MCL of 10.0 mg/L-N. <br /> 2.3.6 Impact of Nitrate Loading to Nearby Water Sources <br /> Since the subject property building area is relatively flat, we do not foresee percolating effluent <br /> affecting any surface water resources. <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 (9.5 <br /> mg/L N) indicates that the development on the parcel is not anticipated to cause a buildup of <br /> nitrates in the aquifer above the MCL of 10 mg/L-N. <br /> Responsive ■ Resourceful ■ Reliable 15 <br />