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h'q KLEINFELDER <br /> Test Number Parcel Performed Depth (feet) Percolation Rate <br /> (min./inch) <br /> P-1 A 3.1 0.7 <br /> P-2 B 3.0 85.0 <br /> P-3 C 3.1 11.1 <br /> 7. NITRATE LOADING CALCULATIONS <br /> Per SJCEHD requirements, the following summarizes our nitrate loading calculations for the <br /> proposed leach field. The state drinking water standard for nitrate is 45 milligrams per liter <br /> (NO3) and 10 mg/1 as Nitrogen (N) in groundwater. In our evaluation of nitrate loading, we <br /> have used the Hantzsche mass balance equation (source: Predicting Groundwater Nitrate- <br /> Nitrogen Impacts, Hantzsche and Finnemore (1992)), which is presented below with an <br /> explanation for each factor and the value used in our study. The selection of parameters was <br /> based on previous studies and investigations performed by our firm and others, San Joaquin <br /> County Sewage Standards, previous communication with Mr. Mike Huggins with SJCEHD, <br /> and information provided in a report dated March 19, 1997 prepared by the Questa Engineering <br /> Corporation and authored by Mr. Hantzsche for a development in the Stockton area. Current <br /> -- laws allow two homes on each parcel. We present these calculations based on two single- <br /> family residences over 80 acres, which represents the maximum concentration of homes on any <br /> of the three proposed parcels. <br /> N, =AWN,, (1-D)_+Nb R <br /> AW+R <br /> Where: <br /> N, = Average calculated nitrate-nitrogen in groundwater resulting from domestic sources <br /> and precipitation—mg/l, as N. <br /> A = Number of dwelling units per acre on septic tanks (unit/acre) = 0.03 (based on two <br /> homes divided by 80 acres.) <br /> W = Annual wastewater loading per dwelling unit per acre (inches) = 2.0 inches (per year <br /> per dwelling unit assuming a flow of 150 gal/day/dwelling unit.) <br /> NW = Nitrate concentration of nitrified leachfield effluent (mg/1) = 40 mg/l ((Hantzsche <br /> and Finnemore (1992) based on residential uses.) <br /> D = Percent dentrification of leachfield effluent = 0.1 percent (0.1 to 0.35 percent typical <br /> per Hantzsche and Finnemore (1992)). 0.1 selected given the depth to groundwater. <br /> 48067.G01/ST04R1257 Page 5 of 8 <br /> ©2004 Kleinfelder,Inc. September 29,2004 <br />