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B. CALCULATED NITRATE-NITROGEN LOADING <br /> NLS§ 3.3. The calculated or estimated nitrate-nitrogen impact to the s7anddate7ttoe <br /> groundwater is difficult to determine due to the number of variables involved. These variables <br /> include 1.) Variability in wastewater flows, nitrogen concentrations and dilution effects that may <br /> �} occur, 2.) Impact from previous on-site operations, 3.) Upgradient nitrate sources from agricultural <br /> farmland, 4.) Changes in groundwater directional flow and elevation, 5.) Denitrification potential <br /> of the underlying soil, and 5.) Rainfall recharge. <br /> Various scientific methods are used to estimate nitrate-nitrogen loading. This study uses the <br /> Hantzsche/Finnemore Formula to predict the average concentration of nitrate-nitrogen in effluent <br /> recharge water. <br /> NLS§ 3.4,3.5, 3.6. PREDICTED NITRATE-NITROGEN LOADING FROM THE ENTIRE <br /> PROPOSED HARNEY LANE WINERY PROJECT USING THE MAXIMUM AVERAGE DAILY <br /> FLOW (ADF) OF 450 GPD BASED ON THE PARAMETERS DESCRIBED, AND TAKING THE <br /> ENTIRE PROJECT AREA OF 40.0 ACRES INTO CONSIDERATION. THIS LAND AREA IS <br /> USED BECAUSE THE A.P.N. PARCEL IS THE SMALLEST UNIT OF AREA THAT DESCRIBES <br /> A PARTICULAR PROJECT: <br /> HANTZSCHE/FINNEMORE E UA TION <br /> lNw(1 - d) + R Nb <br /> Nr— (I + R) <br /> Where: <br /> Nr= Resultant average concentration of nitrate-nitrogen in recharge water- (ppm NO,-N) <br /> I — Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr <br /> Nw = Total nitrogen concentration of wastewater in mg N/L <br /> d = Fraction (%) of nitrate-nitrogen loss due to denitrification in the soil <br /> R = Average recharge rate of rainfall - inches per yr NLS§ 3.2 <br /> Nh = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences <br /> (ppm NO3-N) <br /> Values and Assumptions <br /> 1= 450 gpd x 365 d/yr of operation —164,250 gals =total WW/yr=21.958 cu ft = 0.15 in. <br /> 40.0 Ac x 43,560 sq ft/Ac x (1 ft/12 in.) <br /> r� <br /> Nw = 103 mg NIL: 1.0%reduction from the 1,600 gallon septic tank = (1-0.1)103 =93 mg N/L 7 -" <br /> d — Assume 25%due to the clay content of the native soil and the observed reduction of nitrate-nitrogen content <br /> from the 42 inch depth to the 25 ft depths. <br /> R — 15 in/yr. <br /> Nb= Assumed to be 0.1 pm NO,-N <br /> 0.15 in/ 93 m N/L (1 -0.25) + (15 in/yr x 0.1 mg/L) <br /> Nr = (0.15 in/yr+ 15 in/yr) <br /> t 1 Nr = 1.0 ppm as nitrate-nitrogen (NO,-N) or 4.5 ppm as nitrate (NO,) <br /> Chesney Consulting <br />