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Soil Suitability and Nitrate Loading Evaluation Page 4 <br /> U of P-Golf Practice Facility Expansion _ <br /> 6301 West Eight Mile Road <br /> Stockton, California <br /> May 13 2019 CTE Job#25-0711 G <br /> with the San Joaquin County Environmental Health Department (SJEHD) Document 42- <br /> 014 (January 2017). Percolation test data is presented in Appendix B. <br /> --The percolation test utilized a 6.0-inch diameter test hole excavated to a depth of about <br /> - 36-inche__ d grain nine (4-inch diameter), slotted within the lowermost 6-inches, placed <br /> within the hole. Pea gravel was used at the base and annular space to limit sloughing of <br /> the boring walls. Preliminary information was obtained by adding 12-inches of potable <br /> water, 12.0-inches of water remained in the hole after the 60 minutes (no take). <br /> 9.0 NITRATE LOADING CALCULATIONS <br /> Per SJEHD requirements, the following summarizes our nitrate loading calculations for <br /> the proposed leach field. The state drinking water standard for nitrate is 45 milligrams <br /> per liter (NO3) and 10 mg/l as Nitrogen (N) in groundwater. Presented below is our <br /> evaluation of nitrate loading which uses the Hantzshe mass balance equation (source: <br /> Predicting Groundwater Nitrate-Nitrogen Impacts, Hantzshe and Finnemore; 1992). <br /> N,= [I(NW)(1-D)+R(Nb)] /(I+R) <br /> Nc = Calculation of nitrate-nitrogen in groundwater resulting from leach field <br /> source and precipitation(mg/l, as N). <br /> I = Volume rate of waste water entering the soil averaged over the gross <br /> developed area <br /> I = 275 gal/day (Appendix D, septic system design flow calcs) x 365 <br /> days/year x ft3/7.48 gallons x 1 acre/ 43,560 ft2 x 12 inches / foot x 1/10 <br /> acres <br /> 0.37 inches/year <br /> NW = Nitrate concentration of nitrified leach-field effluent is assumed to be on <br /> the order of 70 mg/l (per Soil Suitability&Nitrate Loading Study report <br /> by Kleinfelder, Inc., dated August 30, 2005). <br /> D = Fraction of nitrate-nitrogen loss due to denitrification of leach field <br /> effluent is assumed to be on the order of 0.20 (per Hantzshe and <br /> Finnemore(1992)0.10 to 0.35 is typical). <br /> R = Average recharge rate due to rainfall = 11.2 inches per year(taken as 80% <br /> of annual 14.0 inches, 20% assumed lost to offsite drainage & <br /> evapotranspiration). <br /> cAl <br />