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determinations are based on current and particularly long-term growth projections. The following calculations demonstrate flow projections: It is assumed there no cooking within the kitchen of the residence/office and therefore no use of a garbage disposal and therefore, nor heavy organic loading. The characteristics of the wastewater flow will be predominately blackwater, with a comparatively small volume of sink water and no graywater from the washing of clothes,bathing, etc. Kitchen wastewater may consist of juices or other similar type liquids to the system. B. CALCULATED IMPACT FROM NITRATE-NITROGEN LOADING From the anticipated wastewater characteristics described, the nitrogen emanating from the project may be at a slightly higher concentration than what would normally be found in a typical _ domestic or household system. This can be attributed to the lack of a dilution effect which graywater would provide. The scientific literature cites nitrogen concentrations in septic effluent (residential) typically ranging from 17 mg N/L for basins, sinks, etc. to 140 mg N/L for toilet wastes. Therefore, considering a 70/30 percent usage for toilet water volume and sink water volume, respectively, a value of 103 mg N/L of septic effluent will be used to calculate nitrate- nitrogen loading for this project. The loading projection is based on the original occupancy of one guard and one on-site office staff and 20 additional people added to the system on a daily basis. This number will create a "safety factor" and is also based on 17 car spaces. Each person is assigned 10 gallons per day: 22 people X 10 gals/person/day=220 gals/day X 3.79 L/gal= 834 L/day X 103 mg N/L = 86 grams N/day X 365 days/yr= 31 kg N/yr X 2.2 Ib/kg=69 lbs N/yr When an areal contribution is considered, a concentration of 91bs of nitrate-nitrogen is projected: 69 lbs N/yr- 8 ac=91bs NO3-N. The following reductions in the nitrate-nitrogen loading from above are anticipated, according to _ the scientific literature: Septic tank(as designed) removes 50%N x 69 lbs= 35 lbs Biomat formation removes 10%X 35 lbs=3.5 lbs Denitrification in silt soil strata removes 25%X 31.5 lbs= 8 lbs 69 lbs -47 lbs =22 lbs N/yr total nitrogen load. Determination of the theoretical nitrogen contribution to the groundwater: Assume 85% reduction in N (from above) = 86 grams N/day - 85%= 13 grams N oxidized to nitrate-nitrogen. Dilution water available (avg water use), QAVE= 220 gal/day +avg groundwater flow(Qg,,,) Groundwater flow perpendicular to 100 linear ft of leachfield area= k(hydraulic conductivity of sat. zone)x(i)x 2.5 ft (top mixing layer) X 100 ft= Q9W=2 X 10-3 ft/min(estimated)x(60 min/hr x 24 hrs/day) 0.02 x 2.5 ft x 100 ft= 14 113/day or 108 gals/day 4 ,. Vaffey Ag 4rsearch