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Values and Assumptions: <br />I = 971,712 gals = total WW/yr = 129,908 cu ft = 1.157 in/yr <br />30.94 Ac x 43,560 sq ft/Ac x (1 ft/12 in) <br />Nw = 90 mg N/L <br />d = Assume 25% due to the high percentage of clay soil (29%) throughout the soil profile that not only <br />mitigates nitrification, but also promotes denitrification of nitrate molecules that may form. <br />R= 13 in/yr. <br />Nb = Assumed to be 0.1 ppm NO3-N <br />1.157 in/yr (90 mg N/L) (1 -0.25) + (13 in/yr x OA mg/L) <br />Nr = (1.157 in/yr + 13 in/yr) <br />Nr = 5.6 ppm as nitrate-nitrogen (NO3-N), or 25 ppm nitrate. <br />CONCLUSIONS <br />The rainfall Mass Balance Approach used in the Nitrate Loading calculations above indicates a resultant average <br />concentration of nitrate-nitrogen (NO3-N) in the recharge water to be 6.7 ppm. Using the Isohyetal Rainfall Data <br />as total rainfall recharge in the Nitrate Loading calculations, a resultant average concentration of nitrate-nitrogen <br />in recharge water is found to be 5.6 ppm; a difference of 1.1 ppm between the two data/calculation procedures <br />with both procedures below the MCL for nitrate-nitrogen of 10 ppm. <br />Respectfully submitted, <br />CHESNEY CONSULTING <br />Don Chesn ,PE <br />Registered Civil Engine #C75479 <br />CA Registered Nitrogen Management Specialist #341829 <br />Page 3 of 3 <br />Chesney Consulting