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KLE/NFELOER gyne noao.+'gem samw„ 10 NITRATE LOADING CALCULATIONS Per SJCEHD requirements, the following summarizes our nitrate loading calculations for the entire parcel, including the existing two septic systems and the proposed septic system. As a conservative approach, the MicroSepTec system discussed above will not be taken into consideration in our nitrate loading calculations. Instead, all systems will be treated as conventional septic systems with septic tanks and leach fields. The state drinking water standard for nitrate is 45 milligrams per liter (NO3) and 10 mg/I as Nitrogen (N) in groundwater. In our evaluation of nitrate loading, we have used the Hantzsche mass balance equation (source: Predicting Groundwater Nitrate-Nitrogen Impacts, Hantzsche and Finnemore (1992)), which is presented below. Nc 1(%)(1-D) + R(Nb) (I+R) The selection of parameters used in the equation was based on previous studies and investigations performed by our firm and others, San Joaquin County Sewage Standards, and information provided in a report dated March 19, 1997 prepared by the Questa Engineering Corporation and authored by Mr. Hantzsche for a development in the Stockton area. Average calculated nitrate-nitrogen in groundwater resulting from leach field source N, _ and precipitation—mg/1, as N. Volume rate of waste water entering the soil averaged over the gross developed area I = = 1.07 inches per year (calculated as follows: ([14,700 gal/week x 52 weeks/year x 0.1337 cubic fugal]/[26.31 acres x 43,560 sq ft/acre]) x 12 inches/ft) Nitrate concentration of nitrified leach-field effluent (mg/1) = 45 mg/I (The Hantzsche and Finnemore (1992) technical paper indicates that the average total nitrogen Nw = concentration in septic tank effluent ranges from 35 to 45 mg/I. This range was also reported in the 1996 Dames and Moore technical memorandum.) 20162869.001 A/STO1 6R38644 Page 10 of 15 April 19, 2016 0 2016 Kleinfelder