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Soil Suitability/ Nitrate Loading Study <br /> Betschart Property Lodi, CA 1rerracon <br /> July 19, 2019 Terracon Project No. NA197044 <br /> Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 <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 leach field is expected to be located <br /> within clayey sandy soils; therefore, denitrification estimate of 15 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 Leachrield Deep <br /> Acres Concentration Percolation <br /> Land Use (Nc)" Daily Flow Denitrification <br /> (mg/L-N) (A) (Q)(gpd) (Nw) ) (d) o IR)lin Il <br /> (mg/L-N <br /> Proposed Residence 9.5 4.25 420 45 15% 4.49 <br /> "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 9.5 mg/L-N <br /> below 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 /> water source is an irrigation channel and/or river overflow area located to the adjoining north of <br /> the site. As the topographic gradient is westerly and the site is relatively flat, we do not foresee <br /> percolating effluent affecting surface water resources north of the 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 (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 im Resourceful ® Reliable 16 <br />