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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 Paize <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 /> h.,.i = Volume rate (Gal/day) of waste water entering the soil from 1 fixture and <br /> Stores, per toilet fixture"= 150 gal/fixture (per SJC Onsite Wastewater Treatment <br /> Systems Standards, January 2017): <br /> 2 x 150 = 300 gal/day. <br /> h w= Volume rate converted to inches/year and averaged over the gross developed <br /> area(using 1/4.94 acre): <br /> = 300 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 /> 0.816 inches/year. <br /> NW= Nitrate concentration of nitrified leach-field effluent is assumed to be on <br /> the order of 40 mg/1 (average is 35 to 45 mg/1 per Hantzsche and <br /> Finnemore; 1992). <br /> % <br /> T,INC- <br />