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15 gallons/capita/day (Per Sewage Standards: Industrial Buildings with no cafeteria) <br /> 100 people X 15 gals/person/day= 1,500 gals/day X 3.79 L/gal = 5,685 L/day X 103 mg N/L = <br /> 586 grams N/day X 313 days/yr(6 days/wk, excludes Sundays) = 183 kg N/yr X 2.21b/kg= <br /> 404 lbs N/yr <br /> When an areal contribution is considered, a concentration of 14 lbs NO3-N/Ac is projected: <br /> 404 lbs N/yr_29 ac= 14 lbs NO3-N/Ac. <br /> The following reductions in the nitrate-nitrogen loading from above are anticipated, according to <br /> the scientific literature: <br /> Septic tanks (as designed)removes 50%N x 404 lbs=202 lbs <br /> Biomat formation removes 10%x 202 lbs= 182 lbs <br /> Denitrification in silt soil strata removes 20%x 182 lbs= 146 lbs <br /> 146 lbs N/yr total theoretical nitrogen load. <br /> Determination of total theoretical nitrogen loading to the underlying groundwater: <br /> Assume 80%reduction in N (from above) = 586 grams N/day - (50% + 10%+20%)_ <br /> 212 grams NO3-N/day - assuming complete oxidation of N to nitrate-nitrogen. <br /> Due to the unknown sizes of the leachfields for business other than the Site Approvals, calculated <br /> nitrogen concentration to the underlying groundwater can only be made on a total areal basis: <br /> Assumptions: <br /> 1. No rainfall contribution(Since most of the area is paved, roofed or compacted road base). <br /> 2. No contribution from retention basins <br /> 3. Groundwater gradient approximately 0.002 ft/ft(2 ft fall/1000 ft) <br /> 4. North-south property distance is 1,100 ft and groundwater flows perpendicular(east-to-west). <br /> Dilution water available (avg water use), QAvg= 1,500 gal/day+avg groundwater flow(Qg,,.) <br /> Groundwater flow perpendicular to 1,100 linear ft of property area= <br /> k(hydraulic conductivity of sat. zone)x(i) x 10 ft(top mixing layer)x 1,100 ft= <br /> Qg,, =2 X 10-2 ft/min (estimated) x (60 min/hr x 24 hrs/day) x 0.002 ft/ft x 10 ft x 1,100 ft= <br /> 634 ft /day or 4740 gals/day <br /> CALCULATED NITROGEN CONCENTRATION TO GROUNDWATER UNDER PROJECT= <br /> 212grams/QAyg+Qg„ =212 g_ [(1,500 +4740)3.78] x 1000=9 mg/L NO3-N/day <br /> H. SEPTIC SYSTEM DESIGN / IMPACT MITIGATION <br /> The design of each Site Approval septic system is based upon consideration for environmental <br /> protection, proper operation and longevity. Plumbing fixtures must consist of low volume <br /> fixtures as specified in the Uniform Plumbing Code (UPC)to prevent excessive water usage. <br /> The system design parameters for each Site Approval can be found in Appendix D, along with <br /> the issued permit. <br /> 6 <br /> Vaffey Ag 9igsearck <br />