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rC <br /> L 33. PREDICTED NITRATE-NITROGEN LOADING FROM THE <br /> E BUILT-OUT ICEHOUSE PROJECT USING THE MAXIMUM AVERAGE <br /> AILY FLOW(ADF) BASED ON THE PARAMETERS DESCRIBED ON PAGE 12 AND <br /> TAKING THE ENTIRE PROJECT AREA INTO CONSIDERATION: <br /> HANTZSCHEIFINNEMORE EQUATION <br /> I&(1 - d) + RNA <br /> Nr= (I+R) <br /> Where: <br /> Nr= Resultant average concentration of nitrate-nitrogen in recharge water -(ppm NO,-N) <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr <br /> Nw= Total nitrogen concentration of wastewater in mg N/L <br /> d = Fraction(%)of nitrate-nitrogen loss due to denitrification in the soil <br /> R = Average recharge rate of rainfall -inches per yr NLS§3.2 <br /> Nb= Background nitrate-nitrogen concentration of rainfall recharge,exclusive of wastewater influences <br /> (ppm NO,--N) <br /> Values and Assumptions <br /> I= 2,108 gals/d x 250 work d/vr=527.000 gals =total WW/yr=70,454 cu ft = 2.39 in. <br /> 8.1 Ac x 43,560 sq ft/Ac x (1 ft/12 in.) <br /> Nw = 113 mg N/L: 10%reduction from each of four septic tanks=(1-0.4)113 =67.8 mg N/L <br /> d = Assume 30%due to the high clay content soils and apparent denitrification observed in the soil chemistry results. <br /> R = 9 in/yr. <br /> Nb= Assumed to be 0.1 ppm NO3-N <br /> 2.39 in/yr(67.8 mg N/L) (1 -0.30)+(9 in/yr x 0.1 mg/L) _ ) U3 <br /> Nr = (2.39 in/yr+9 in/yr) <br /> P</Nr 10.0 pp s nitrate-nitrogen(NO3-N or 45.0 ppm nitrate (NO,) <br /> The calculated nitrate loading concentration in the recharge effluent is calculated to be at the <br /> Maximum Contaminant Level limit for nitrate in drinking water. The variables used in the <br /> calculations above are conservative. For example, the use of 113 mg N/L, which was determined <br /> from actual septic tank effluent from a Tracy commercial facility, is a much higher nitrogen <br /> concentration than those concentrations published in the sources referenced in Table 5. Secondly, <br /> various researchers place the nitrogen reduction occurring in septic tanks at 10%to 20%. From the <br /> May 8, 2003 Symposium"Onsite Wastewater Treatment-Nitrogen Removal,"Dr. Stuart Oakley of <br /> Chico State University states that"approximately 20%of the total nitrogen generated is removed in <br /> the septic tank" As noted above, a conservative estimate of 10%was used for each of the four tanks <br /> through which the effluent will travel. <br /> 14 <br /> Chesney Consulting <br />