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%.. _- .. <br /> �� KLEINEELDER <br /> Nc = I(Nw)(1-D) + R(Nb) <br /> (I+R) <br /> ` The selection of parameters used in the equation was based on previous studies and <br /> investigations performed by our firm and others, San Joaquin County Sewage <br /> ` Standards, previous communications with Mr. Mike Huggins and Mr. Rodney Estrata <br /> with SJCEHD, and information provided in a report dated March 19, 1997 prepared by <br /> the Questa Engineering Corporation and authored by Mr. Hantzsche for a <br /> ` development in the Stockton area. <br /> NG = Average calculated nitrate-nitrogen in groundwater resulting from [each field <br /> source and precipitation — mg/I, as N. <br /> I = Volume rate of waste water entering the soil averaged over the gross <br /> developed area = 0.45 inches per year calculated as follows: (4,200 <br /> al/week x 52 weeks/year x 0.1337 cubic ft/gal)/(18 acres x 43,56 <br /> acre) x 12 inches/ <br /> Nom, = Nitrate concentration of nitrified leach-field effluent (mg/[) = 45 mg/I (Based <br /> on the Hantzsche and Finnemore (1992) technical paper which indicates <br /> that the average total nitrogen concentration in septic tank effluent ranges <br /> form 35 to 45 mg/l. This range was also reported in the 1996 Dames and <br /> Moore technical memorandum.) <br /> D = Fraction of nitrate-nitrogen loss due to dentrification of leach field effluent = <br /> 0.25 (Per Hantzsche and Finnemore (1992), 0.10 to 0.35 is typical). The <br /> value was selected given the depth to groundwater in the project area. <br /> R = Average recharge rate of rainfall = 8.05 inches per year (representing 60 <br /> percent of the average annual rainfall of approximately 11.5 inches. The <br /> remaining 40 percent of rainfall is assumed to drain off-site into natural or <br /> manmade drainages or be lost to evapotranspiration.) <br /> Nb = Background nitrate nitrogen concentration of rainfall recharge at the water <br /> table = 0.5 mg/I (per Technical Memorandum, Hydrologic and Soil <br /> ` Investigation for the Chico Urban Area, page 6, Dames and Moore, April <br /> 1996) <br /> ` Our calc Ion that inclu both-the proposed-temp+e- a existing home is as <br /> follows: <br /> ` N� = 0.45(45)(1-0.25) + (8.05)(0.5) = 2.26 mg/I as N <br /> (0.45 + 8.05) <br /> L <br /> 43498.G01/ST05R1014 September 27,2005 <br /> ` Copyright 2005 Kleinfelder,Inc. Page 5 of 7 <br />