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f k4 KLEINFELDER <br /> _ Depth of Test Hole Percolation Rate <br /> Lot Number Date of Test feet Min <br /> ./inelt <br /> 3.0 Did Not Pere. �- <br /> _ 13 January 26, 2005 16.5 7.6 <br /> 3.0 9.6 <br /> r 14 January 26, 2005 13.7 7.1 <br /> 3.5 62.5 + ti <br /> 15 January 26, 2005 13.6 11.9 <br /> 3.1 3.2 <br /> 16 January 28, 2005 13.8 9.3 <br /> 3.1 41.7 <br /> 17 January 28, 2005 19.0 11.9 <br /> 7. NITRATE LOADING CALCULATIONS <br /> Per SJCF-HD requirements, the following summarizes our nitrate loading calculations for the <br /> proposed leach fields. The state drinking water standard for nitrate is 45 milligrams per liter <br /> (NO3) and 10 mg/l 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. Therefore, we present these calculations based on two <br /> single-family residences on each of the 1.7 proposed parcels. <br /> N, = AWN,, (1-DI+ (N R <br /> AW -+- R <br /> Where: <br /> N, = Average calculated nitrate-nitrogen in groundwater resulting from domestic sources <br /> and precipitation — nig/l, as N. <br /> A = Number of dwelling units per acre on septic tanks (unit/acre) = 0.8 (based 34 homes <br /> (two homes on each of the 17 lots) divided by 42.9 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 /> 52709.GOI/ST05R550 May 9,2005 <br /> ©2005 Kleinfelder, Inc. Page 5 of <br />