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Calculated nitrate-nitrogen loading: L&(] -d)+RN, Nr= (I+R) Where: Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm 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 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 Values and Assumptions: j j I=250 gpd x 365 d/yr=91.250 gals=total WW/vr=12.199 cu ft =4.54 in/yr 0.74 Ac x 43,560 sq ft/Ac x (1 ft/12 in) Nw=36 mg N/L as determined above. d = 30%from the fine-grained loam fraction of the soil, as described in Ref. 8,Pgl0. However,there is potential evidence of significant(50%)denitrification within the on-site soils. R = 8.67 in/yr from Table 3. Nb= Assumed to be 0.1 ppm NO3-N 4.54 in/yr(36 mg N/L) (I -0.30)+(8.67 in/yr x 0.1 mg/L) Nr = (4.54 in/yr+8.67 in/yr) Nr = 8.7 ppm as nitrate-nitrogen (NO3-N) or 38.8 ppm as nitrate (NO3) EFFLUENT DISPOSAL OPERATIONAL PARAMETERS A filter bed disposal structure and three -42" dia. seepage pits will be installed for this project, as illustrated on the attached site plans. Required lineal ft of leachline (LFLL) =400 X 4= 1,600 sf of filter bed area. The filter bed dimensions are to be: 20 ft N-S and 65 ft E-W= 1300 sf+each 42" pit= 80 ft LL X 3 =240+ 1,300= 1,540 sf. Although a 1,600 gallon septic tank is required, a 2,000 gallon tank is specified to be installed on the east side of the new house. The 100%replacement area is also denoted on the site plans and is a slightly different configuration due to a 10 ft setback from the garage. Page -7- Chesney Consulting