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Nitrate Mass Balance Calculation 241 4th Street, French Camp, CA Data Input: Result: Effluent Quantity (Q): 1,509 gals/day Concentration Rain (Nb): 1.0 mg/L-N Effluent Stream (Nw): 100 mg/L-N Denitrification (d): 35% Site Area (A): 13.91 Acres Deep Perc. of Rain (R): 8.99 in/yr Waste Loading (W): 1.46 in/yr Mass Balance (Nc): 9.9 mg/L-N MCL Drinking Water Nitrate as N: 10 mg/L-N Percent of MCL Nitrate as N 99% Equations: (W) in = (Q) gal x 1 ft3 x 365 day x 1 acre x 12 in x 1 yr day 7.48 gal 1 year 43,560 ft2 1 ft (A) acre Find (W) 1.46 in/yr (site) = 1,509 gal/day x (1 cu-ft / 7.48 gals ) x (365 days/ 1 year ) x (1 acre / 43,560 sq-ft) x (12 in / 1 ft) x (1 site / 13.46 acres) Nc = WNw(1-d)+RNb W+R Hantzsche-Fennemore Equation (Nc) 9.9 mg/L-N = ((1.46 in/yr x 100 mg/L-N x (1-0.35))+(8.99 in/yr x 1mg/L-N))/(1.46 in/yr + 8.99 in/yr ) Variables: Nc = Average nitrate-N concentration (mg/l) of combined effluent and rainfall percolate (9.9 mg/L-N). W = Uniform waste water loading for study area (in/yr) (1.46 inches/year). Nw = Total nitrate-N concentration of waste water percolate (100 mg/L-N). d = Fraction of nitrate-N loss due to denitrification in the soil (35%), significant clay in shallow soil. R = Uniform deep percolation of rainfall (8.99 in/yr). Nb = Background nitrate-N concentration of rainfall (1 mg/L-N). Assumptions: 1. Total nitrogen concentration of waste stream based on estimate of 100 mg/L-N. 2. Fraction of nitrate-N loss due to denitrification in the soil is assumed to be 35%. 3. Estimated deep percolation of rainfall is 8.99 in/yr, see deep percolation of rain worksheet. 4. Assume background nitrate-N concentration of rainfall is 1 mg/L-N.