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TABLE 3 <br />PRECIPITATION AND Eto DATA FOR TRACY, CA <br />Month <br />Precipitation (in/mo) <br />Eto Average <br />Potential Deep <br />Percolation (in/mo) <br />(in/mo) <br />Adj. Et <br />January <br />2.93 <br />1.24 <br />0.74 <br />2.19 <br />February <br />2.21 <br />1.96 <br />1.18 <br />1.03 <br />March <br />2.38 <br />3.41 <br />2.05 <br />0.33 ' <br />April <br />1.51 <br />5.10 <br />3.06 <br />May <br />0.71 <br />6.82 <br />4.09 <br />-- <br />June <br />2.09 <br />7.80 <br />4.68 <br />-- <br />July <br />0.28 <br />8.06 <br />4.84 <br />-- <br />August <br />1.05 <br />7.13 <br />4.28 <br />-- <br />September <br />0.84 <br />5.40 <br />3.24 <br />-- <br />October <br />1.06 <br />3.72 <br />2.23 <br />-- <br />November <br />2.10 <br />1.80 <br />1.08 <br />1.02 <br />December <br />2.38 <br />0.93 <br />0.56 <br />1.82 <br />TOTALS (in.) <br />13.18 <br />57.0 <br />------ <br />6.39 <br />HANTZSCHE/FINNEMORE EQUATION <br />INW(1- d)+RNb <br />Nr = (I + R) <br />Where: <br />Nr = Resultant average concentration of nitrate -nitrogen in recharge water - (ppm NO3-N) <br />I = Volume rate of wastewater entering the soil averaged over the gross developed area in in/yr <br />Nw = Total nitrogen concentration of wastewater in mg N/L <br />d = Fraction (%) of nitrate -nitrogen combined loss in the soil due to denitrification. <br />R = Estimated Annual Rainfall Recharge in in/yr <br />Nb = Background nitrate -nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br />(ppm NO3-N). <br />Values and Assumptions: <br />I = 400 gpd x 365 d/yr = 146,000 gals/yr = total WW/yr = 19,519 cu ft = 5.6 in/yr <br />0.96 Ac x 43,560 sq ft/Ac x (1 ft/12 in) <br />Page -3- <br />Chesney Consulting <br />