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C ` NLS§3.4,3.5,3.6. PREDICTED RATE-NITR GEN LOADING FROM THE PROPOSED SAHIB TRACY FO PHASE H US NG THE MAXIMUM AVERAGE DAILY FLOW rGURUDWARA ADF) OF 472 GPD BASED ON T PARAMETE S DESCRIBED,AND TAKING THE ENTIRE PROTECT AREA OF 2.29 ACRES I O CONSID RATION: HANTZSCHE/FINNEMORE EQUATION INW 1 -d +RN Nr= (I+R) Where: Nr= Resultant average concentration of nitrate-nitrogen in recharge water-(pprn NO,-N) I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr Nw= Total nitrogen concentration of wastewater in mg NIL d = Fraction(%)of nitrate-nitrogen loss due to denitrification in the soil R = Average recharge rate of rainfall-inches per yr NLS§3.2 Nb= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences (ppm NO3-N) Values and Assumptions I= 4.72 gpd x 365 d/)E= 172,280 gals=total WWlyr,=23,032 cu ft = 2.77 in. 2.29 Ac x 43,560 sq ft/Ac x(I ft/12 in.) Nw = 113 mg N/L: 20%N reduction occurring in the septic tank and 10%in biomat=(1-0.3)113 =79 mg N/L d = Assume 25%due to the clay loam nature of the native soil and therefore medium-high denitrification potential R = 9.25 in/yr. Nb= Assumed to be 0.1 pprn NO3-N 2.77 in/yr(79 mg N/L) Q - .25) + (,9.25 in/yr x 0.1 mg/L) Nr = (2.77 in/yr+9.25 in/yr) Nr 13.7 m as nitrate-nitrogen(NO3-N) or 61 ppm as nitrate(NO3) The calculated nitrate loading concentration in the recharge effluent from Phase H of the Gurudwara Sahib Tracy is calculated to exceed the Maximum Contaminant Level limit for nitrate in drinking water by 37%. However,as will be discussed in the following Conclusions Section of this report, although this resultant recharge concentration exceeds the MCL, it will cause a dilution effect to the nitrate concentration in the receiving water table. Other factors to consider with the nitrate loading calculations are the following: The variables used in the i nitrate loading calculations above are conservative. For example,the use of 113 mg NIL,which was determined from actual septic tank effluent from three Places of Worship in San Joaquin County is a much higher nitrogen concentration than those concentrations published in the sources referenced in Table 7. ! Secondly, the ADF is based on EHD criteria which is extremely conservative and forces a higher nitrate loading potential. Additionally, from the May 8, 2003 Symposium"Onsite Wastewater Treatment-Nitrogen Removal,"Dr. Stuart Oakley of Chico State University states that"approximately 20%of the total nitrogen generated is removed in the septic tank."As noted above,this estimate of 20%was used for nitrogen j reduction occurring in the septic tanks. 15 Chesney Consulting