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NLS§3.4,3.5,3.6. PREDICTED NITRATE-NITROGEN LOADING FROM THE SUNSET KENNELS FACILITY USING THE MAXIMUM AVERAGE DAILY FLOW (ADF) OF 280 GPD BASED ON THE PARAMETERS DESCRIBED,AND TAKING THE ENTIRE PROJECT AREA OF 0.58 ACRES INTO CONSIDERATION: HANTZSCHEIFINNEMORE EQUATION INW(1 - d, +RNb Nr= (I +R) Where: Nr= Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO3-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 N/L 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= 280 gpd x 365 d/ r�peration= 102,200 gals=total WW/yr= 13,663 cu ft = 6.5 in. 0.58 Ac x 43,560 sq ft/Ac x(I ft/12 in.) �z��•8 x b,D833333 Nw =32 mg N/L: 10% reduction from the septic tank =(1-0.1)1 l 3 =29 mg N/L d = Assume only 10%due to the observed increase in nitrate-nitrogen depth. R = 15 in/yr. Nb= Assumed to be 0.1 ppm NO3-N 6.5 in/yr 29 mg N/L)_(1 -0.10)+Q 5 in/yr x 0.1 my,/L) ; _ D Nr = (6.5 in/yr+ 15 in/yr) z/.S Nr = 7.9 ppm as nitrate-nitrogen(NO3-N)or 35.4 ppm as nitrate(NO3) The calculated nitrate loading concentration in the recharge effluent from the proposed expansion facility is calculated to be under the Maximum Contaminant Level limit for nitrate in drinking water, provided that the ADF is not exceeded. The variables used in the calculations above are very conservative. For example,the use of 113 mg N/L,which was determined from actual septic tank effluent from three commercial facilities is a much higher nitrogen concentration than those concentrations published in the sources referenced in Table 5,and takes into account the same nitrogen concentration from dog urine. Secondly,various researchers place the nitrogen reduction occurring in septic tanks at 10%to 20%. 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, a conservative estimate of 10%was used for the proposed 2,000 gallon septic tank. Thirdly,the biomat does have the beneficial property of removing approximately 10%of the nitrogen from disposal systems. This figure was not used in the nitrate loading calculations also to maintain a conservative loading concentration. 9