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C.B. CALCULATED NITRATE-NITROGEN LOADING <br /> NLS§3.4,3.5,3.6. The calculated nitrate-nitrogen impact to the soil and ultimately to the groundwater under <br /> the proposed disposal area is difficult to determine due to the large number of variables involved. However, <br /> from the analyses of septic tank influent, nitrate loading from the domestic wastewater from the facility can be <br /> reasonably estimated. Some of the Variables that will influence nitrate loading include: 1.)Disposal of <br /> effluent through chambered structures, 2.)Impact from upgradient nitrate sources, 3.) Variability in <br /> wastewater flows,nitrogen concentrations,dilution effects, effluent-and stormwater recharge, 4.) Changes.in <br /> groundwater directional;flow and elevation, particularly due to tidal action, 5:)Denitrification potential within <br /> the soil environment and within the confined and/or unconfined aquifers. <br /> Various scientific methods exist to estimate nitrate-nitrogen loading.-This°.Study.uses the Hantzsche/Finnemore <br /> Formula to predict the average resultant concentration of.nitrate-nitrogen in effluent recharge water,which <br /> cannot exceed 10 ppm nitrate-nitrogen (45 ppm as nitrate). As calculated below,the total acreage of the subject <br /> property,based on the Assessors' Parcel Number,will be used for a total areal loading basis. This will be <br /> correlated with the maximum calculated wastewater ADF flow volume-of 2,493-pd for approximately three <br /> months out of any given year during harvest, as calculated on Page t:5. Although the number of on-site people <br /> will decrease substantially during the remaining nine months of the year,,the maximum-flow volume of 2,493 <br /> gpd must be used to ensure proper operation of the system during harvest/crush. These two factors of areal <br /> loading basis and flow volumes primarily estimate the average resultant concentration of nitrate-nitrogen in the <br /> recharge water. <br /> HANTZS'CHEIFINNEMORE EQ UATION <br /> INW(1 -d)+RNe <br /> Nr= (I+R) <br /> Where: <br /> Nr = Resultant average concentration of nitrate-nitrogen in recharge water=(ppm.NO3-N) <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr <br /> Nw = Total nitrogen (TKN).,conceritration of wastewater as determined in the Dosing Tank <br /> :d Fraction(%)of nitrate-nitrogen loss due to denitrification in:the soil <br /> R = Average recharge rate of rainfall - inches per yr, NL'S§.3.2 <br /> Ne = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br /> Values and.Assurnptions: <br /> I 2,493 gpd'x 365 4/1=909,945 gals/yr=total WW/vr= 121,650 cu ft = '0.48 in/yr <br /> 70.23,Ac. x .43,5 60 sq ft/Ac:x "(1 ft/12 in) <br /> Nw= 130 mg N/L(from analyses) <br /> d = Assume 20% due to fine-grained soil profile <br /> R = 16 in/yr <br /> Nb= Assumed to'be 0.1 ppm NO3-N <br /> 0.48 in/yr(130 m .NLL)�S 1�""0'.�0 ]6 in/yr x 0 l <br /> s -Nr = �_. . . <br /> {0.48 in/yr+ 16 in/yr) 1 <br /> Lt;-N­ ppm us nitrate-nitrogen (NO3-N)or 13.9;ppm as nitrate (NO,) <br /> E <br /> 17 <br /> Chesney Consulting <br />