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F7LS§ ATED IMPACT FROM NITRATE-NITROGEN LOADING 3.6 The calculated or estimated nitrate impact to the soil and ultimately to theextremely difficult to determine due to the number of variables involved. Formber of people to inhabit the houses is unknown and variable. A value of four people per household has been used,which incorporates a safety factor. The nitrate-nitrogen loading will be calculated below under two different methods,both as described by Hantzsche and Finnemore in different publications. In the first equation, the gross developed area is considered as specified in Hantzsche and Finnemore's scientific article in the publication Ground Water(1992). The second equation is based on assessing each residential source per unit area as presented in a 1997 document by Hantzsche. HANTZSCHE IFINNEMORE EQUATION CONSIDERING THE EQUATION IN TERMS OF "GROSS DEVELOPED AREA": IN O -d)+RN6 NT= (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 N mg/L(66 mg N/L/day) d = Fraction(%)of nitrate-nitrogen loss due to denitrification in the soil R = Average recharge rate of rainfall-inches per yr(15.5 in.) NLS§3.2 Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences (ppm NO,-N). Values and Assumptions: 270 gals/house (Pg. 9) x 11 houses(Does not include second unit dwellings SSS§3.7) = 2,970 gpd x 365 d/yr= 1,084,050 gals=7.47 gal per ft' 145,120 cu ft of wastewater 145.120 cu ft/w wastewater I= 14.87 Ac x 43,560 cu ft/Ac ft x (1 ft/12 in) I= 2.69 in/yr Nw= 66 mg/L(Pg.9)- 10%reduction of N in the septic tank=59 mg/L N d = 10%from biomat and 25%denitrification that must be occurring from EHD Groundwater Study of the Morada Area. Nb = Assumed to be 0.1 ppm NO,N 2.69 in/w(59 me N/L) 0 -0.35)+(15.5 in/yr x 0.1 mg/L) Nr = (2.69 in/yr+ 15.5 in/yr) LNr = 5.7 ppm as NO3 N or 25.6 ppm as NO, Page-10- Chesney Consulting