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r owers are 1.8 gpm(New CA standard)and should be restricted to 10 min/shower. Assume 4 owers/day= 18 gals/shower x 4 showers/day= 72 gals/day. arrive at the yearly wastewater production, a workweek would be composed of six days, and 50 eks per year based on Holidays and other designated days off. 320 + 72 = 392 gpd x 6 d/wk x 50 s/yr= 117,600 gals/yr. This yearly wastewater generation will be used for the nitrate loading calculations below. Wastewater Characteristics The domestic wastewater generated from the office and shop buildings will be composed primarily of blackwater from toilets and graywater from hand washing. There will be no high organic loading from food preparation in a cafeteria, but additional graywater flows from showers. Consequently, a nitrogen concentration of 65 mg N/L is used below and is based on septic tank effluent analysis from similar facilities. B. CALCULATED NITRATE-NITROGEN LOADING NLS§3.0,etc. The calculated nitrate-nitrogen impact to the soil and ultimately to the groundwater is difficult to determine due to the large number of variables involved and variables unknown at this time. These include: 1.) Nitrate impact from upgradient agricultural sources, 2.) Variability in wastewater flows, effluent nitrogen concentrations and dilution effects, 3.) Changes in groundwater directional flow and elevation, 4.) The denitrification potential of the indigenous soils. HANTZ.SCHFI,G'INNEMOn,'EOUA'1'ION INWLL-d)+RNb 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/yr Nw = Total nitrogen concentration of wastewater in mg N/L d = Fraction(%)of nitrate-nitrogen combined loss in the soil due to denitrification. R = Estimated Annual Rainfall Recharge in inches/yr. Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences. Values and Assumptions: I = 117,600 gals/-yr= 15,722 cu ft = 0.89 in/yr 4.85 ac x 43,560 sq ft/Ac x(1 ft/12 in) Page -5- Chesney Engineering, Inc.