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Soil Suitability&Nitrate Loading Evaluation CTE Job#25-1084G <br /> New Septic Leech Lines <br /> 21850 East Liberty Rd <br /> Clements, California <br /> January 30, 2021 (Revised 1/17/2022) Page 6 of 9 <br /> and corresponding percolation rates are not inconsistent with those typical of the soil types <br /> encountered in the vicinity. <br /> Owing to variations in material type and depth, percolation rates would typically be expected to <br /> fluctuate somewhat across a site and are also dependent upon actual construction, depth, size, <br /> location, and workmanship of the drainage element. Based on percolation test results, the soil in <br /> the upper 42-inches of the site are low permeable (percolation rate >30 min/inch) and are <br /> considered suitable for a conventional septic tank/leach trench disposal systems. <br /> 9.0 NITRATE LOADING CALCULATIONS <br /> Per SJEHD requirements, the following summarizes our nitrate loading calculations for the <br /> proposed leach field. The state drinking water standard for nitrate is 45 milligrams per liter (NO3) <br /> and 10 mg/1 as Nitrogen (N) in groundwater. Presented below is our evaluation of nitrate loading <br /> which uses the Hantzshe mass balance equation (source: Predicting Groundwater Nitrate-Nitrogen <br /> Impacts, Hantzsche and Finnemore; 1992) attached as Appendix C. <br /> N, = Calculation of nitrate-nitrogen in groundwater resulting from leach field source and <br /> precipitation(mg/1, as N). <br /> NC _ [I (NW) (1-D) +R(Nb)] / (I+R) <br /> Itotat = Volume rate (Gal/day) of wastewater entering the soil from 4 employees and 143 <br /> vehicles per day(Vehicle per day figure Provided by Client)= 10 gal/vehicle <br /> serviced (per SJC Onsite Wastewater Treatment Systems Standards, January <br /> 2017): <br /> ((2 x 4) +143)x 10 = 1510 gal/day. <br /> Itotat= Volume rate converted to inches/year and averaged over the gross developed <br /> area(using 1/4.94 acre): <br /> = 1510 gal/day x 365 days/year x ft3/7.48gal x 1 acre/43,560 ft2 x 12 in/ft x <br /> 1/4.94 acre <br /> %7CAALUNC <br />