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i� 73L. Crites/Tchohano lous Formula LNLw CN F where: L, = nitrate-nitrogen loading in lbs/ac-day LW = wastewater loading in gals/ac-day= 5,400 gals/day- 21.19 ac = 254.8 gals/ac-day CN = nitrogen concentration: average determined to be 56 mg NIL F= conversion factor: 8.34 lbs/[106 gal-(mg/L)] LN= 254.8 gals/ac-day x 56 mg N/L x (8.34)(10-6) = 1.19 lbs N/ac•day x 365 days/yr= 434.4 lbs N/ac/yr. It is generally regarded that people excrete approx. 6 kg N per year, or 13.2 lbs per year: 13.2 lbs N/person/yr x -60 people in the subdivision= 792 lbs N/yr. The effluent disposal areas will be approximately 12,000 sq. Mot x 15 lots =4.1 acres. Therefore, and assuming all nitrogen eliminating converts to nitrate, the nitrate-nitrogen loading is approximately 792 lbs N/yr_4.1 acres =193 lbs N/ac/yr based on the 6 kg/person/yr premise. Therefore, the Crites/Tchobanoglous Formula overestimates the nitrogen-loading on an acre areal basis by a factor of approx. two (434 lbs N/ac/yr vs. 193 lbs N/ac/yr). 4, Calculation of Alkalinity Requirement for Nitrification.- All itrificationAll of the nitrate-nitrogen loading calculations above are contingent upon the environmental factors required for nitrification to occur. These conditions include soil pore-space oxygen content, soil temperature, pH, electrical conductivity, organic matter, cation exchange capacity, and alkalinity. Alkalinity in wastewater effluent is derived from the domestic water supply in addition to the introduction of wastes. Nitrification consumes approximately 7.1 mg of alkalinity for every mg of ammonia-nitrogen(NH4-N) oxidized. The alkalinity from the domestic well boring water reveals a total alkalinity of 71 ppm at depth of 294 it, a total alkalinity of 97 ppm at 350 ft and a total alkalinity of 71 at 458 ft depth. Total nitrification of the average Total Nitrogen concentration of 56 mg/L, as calculated, would require: 56 in L NH,,-N x 7.1 mg CaCO = 398 m L alkalinit . Determining the alkalinity of the groundwater from the tested depths,we find an average alkalinity of 80 ppm. Consequently, it may be that nitrification will be inhibited because of a significant deficiency in the groundwater alkalinity. The introduction of alkalinity from the domestic waste stream would have to be substantial for the nitrification reaction to occur. G. .Agronomic Input Comparisons PROJECTED AGRONOMIC NITRATE IMPACT IF PROPERTY WERE IN WALNUT PRODUCTION i Although the property is currently fallow, the flat portion of the acreage could be planted in ' walnuts,which would be the logical crop since walnuts are being grown adjacent to the north and west of the property. Mature walnut trees may use approximately 250 pounds of nitrogen per acre, which is the total uptake in the harvested portion. Page -14- Chesney Consulting