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r-'l 0 F m previous studies within the County of San Joaquin, a small number of commercial e averaged a Total Nitrogen concentration of 87 mg N/L. This concentration of 87 mg onsidered a high, or strong strength wastewater and will be used in the calculations entire build-out of Phase 1 and Phase 2 because it provides a safety factor to account for the increased organic loading from the three Fast Food Restaurants and one Hotel Restaurant. f Three different equations and formulas will be used below to quantify the nitrate-nitrogen loading for 1! the Complex. These methods include the Hantzsche/Finnemore Equation,the Crites/ j Tchobanoglous Formula from Small and Decentralized Wastewater Management Systems and the ! method presented by O. B. Kaplan in Septic Systems Handbook. However,the Hantzsche/ Finnemore Equation is widely regarded as the scientific basis for nitrate loading calculations. The primary variables involved in the assessment or in quantifying nitrate impact to the underlying groundwater under the subject property are the Total Nitrogen concentration, volume of yearly wastewater flows, extent of denitrification, and the extent of evapotranspiration. Denitrification capabilities of the indigenous surface soils and the fine-grained subsurface soils are expected to increase and substantiate the denitrification potential. Ammonium retention in the clay soils should also be significant, as has been observed in other projects with similar soils. Evapotranspiration has not been factored in any of the three nitrate loading methods; however, it could ultimately be a significant part of wastewater management and consequently nitrate-nitrogen r loading. 5.2 fHant_sc a/JF nnemore Equation-(Ehase IT& Comole�e Build=Out) NLS§ 3.5 INw(1 - dl+R Nb Nr= (I+R) Where: Nr= Resultant average concentration of nitrate-nitrogen in recharge water-ppm NO3-N. I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr. Total wastewater olume ed will be lesser volume calculated in Column 3, Page 17 For both Phase 1 and Phase 2 a 25,080 gp x 365 days/year=9,154,200 gals= 7.48 gals per ft' _ 1,223,800 cu ft of wastewater. Does no account for Eva otrans iration. Nw= Total nitrogen concentration of wastewater at 87 mg N/L based on discussion referenced above. Does not account for loss of nitrogen in septic tanks (15%+) or through biomat(10%+). d = Fraction(%) of nitrate-nitrogen loss due to denitrification in the soil R = Average recharge rate of rainfall: 12 inches per yr(NLS§ 3.2) Nb= Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences(ppm NO,-N) Values and Assumptions 1= 9,154,200 gals = total WW/yr= 1 223 8 ft (= 3:0.66 i 11.00 Ac x 43,560 sq ft/A 1 ft/12 in) Page -19- Chesney Consulting