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Nitrate Loading Study Page 6 Proposed Warehouse 26550 South Banta Road Tracy, California April 15, 2014 CTE Job No 20-2463G installed. Nitrate/nitrogen loading is expected five-and-one-half days per week, based on a five day work week and half day worked on Saturdays. 4.5 Mass Balance of Nitrate/Nitrogen Loading Usina Hantzsche/Finnemore Model The following summarizes nitrate loading calculations for the proposed septic system and leach field to comply with SJCEHD requirements using the Hantzsche /Finnemore Model (Hantzsche /Finnemore, 1992). Offsite sources were excluded as they are not part of the scope of this study, and their impacts are occurring regardless of the results of this study. The model utilized is as follows: nr= [I(nw)(I-d)+R(nb)]/(I+R) nr= Calculation of nitrate-nitrogen in groundwater resulting from leach field source and precipitation (mg/l, as N). 1 = Volume rate of waste water entering the soil averaged over the gross developed area. I= (450 gal/day x 365 days/yr x 1 ft'/7.48 gal)x(1/3.53 acre)x(1 acre/43560 ft')x(12 in/ft) I = 1.71 inches/year nw= Nitrate concentration of nitrified leach-field effluent is conservatively assumed to be on the order of 70 mg/I (per discussion with San Joaquin County previous study). d = Fraction of nitrate-nitrogen loss due to dentrification of leach field effluent is assumed to be on the order of 0.25(0.10 to 0.35 is typical per Hantzshe and Finnemore, 1992). R = Average recharge rate due to rainfall=8.5 incites per year(taken as 80%of annual 10.6 inches, 20% assumed lost to offsite drainage& evapotranspiration). nb= Background nitrate nitrogen concentration of rainfall recharge at the water table is conservatively assumed to be on the order of 1.0 mg/1(typically between 0.5-1.0 mg/I per Hantzshe and Finnemore, 1992). Our nitrate loading calculation is as follows: Using nr= [I(nw)(1-d)+R(nb)]/(I+R), nr= [1.71 in/yr x 70 mg/1(1-0.25)+8.5 in/yr(1.0 mg/1)]/(1.71 in/yr+ 8.5 in/yr) nr=9.6 ma/l as N (average concentration of nitrate-nitrogen loading in recharge water)