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CI = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO,-N) = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr = Total nitrogen concentration of wastewater in mg N/L d = Fraction (%) of nitrate-nitrogen loss due to denai�7ification in'the soil R = Average recharge rate of rainfall -inches perS§3.2 j Nb= Background nitrate-nitrogen concentration of rnf�lLlrecharge, exclusive of wastewater influences (ppm NO,-N) ---_ Values and Assumptions I= 144 gpd x 250 work d/yr=36,000 gals=total WW/yr=4,813 cu ft = 0.14 in. 9.45 Ac x 43,560 sq ft/Ac x(1 ft/12 in.) Nw = 113 mg N/L: 10%reduction from the septic tank =(1-0.1)113 = 102 mg N/L d = Assume 0% due to the sandy nature of the native soil and therefore low denitrification potential R = 11 in/yr. Nb= Assumed to be 0.1 ppm NO,-N 0.14 in/yr(102 mg N/L) (1 -0)+(11 in/)r x 0.1 ma/L) Nr = (0.14 in/yr+ 11 in/yr) Nr = 1.4 ppm as nitrate-nitrogen(NO,-N) or 6.2 p m as nitrate(NO,) The calculated nitrate loading concentration in the recharge effluent from the Office Building is calculated to be under the Maximum Contaminant Level limit for nitrate in drinking water. The variables used in the calculations above are 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 4. 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 septic tank. C. SEPTIC SYSTEM OPERATIONAL PARAMETERS AND COMPONENTS - AREA TO SERVE THE MANTECA RV STORAGE PARK SSS§ 3.7. The design of the pressurized filter bed disposal system for the Manteca RV Storage Park will be under the direction of Mr. Carl Fiorica, R.C.E. of RBF Consulting - Roseville California. Discussion of efficient operation, disposal field longevity, and environmental protection are based upon the environmental parameters discussed below. An overview of the system operation is as follows for the new Office Building: Influent waste from the building will gravity through a four-inch ABS tightline(0.25 inch/1 ft)-into the first compartment of a two-compartment 1,200 gal septic tank. The effluent will then gravity into the second compartment which will be the pump "chamber. This chamber will have an Orenco Biotube filter vault, and a duplex pump system to pressurize effluent for disposal to two filter-beds, as depicted on the Site Plans. As referenced below, each filter bed is to be 10 ft wide and 40 ft long. 12 Chesney Consulting