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_ If a projected maximum daily wastewater flow of 3,500 gallons is used, the following calculations indicate the potential nitrate loading per year: 3500 gallons/day= 13,230 L/day X 62 mg N/L= 0.82 kg N/day X 365 days/year= 300 kg N/yr or 660 lbs. N/yr. Denitrification is the only mechanism in the soil which can significantly reduce nitrate concentrations in percolating effluent. It is the biological and chemical reduction of nitrate to volatile gases, such as nitrous oxide and nitrogen gas. The most favorable soil conditions for denitrification are: 1.) High organic matter content of the underlying soils, 2.) High soil moisture content(anaerobic conditions) and 3.) High soil pH. As can be noted on the Soil Analysis Report, the surface and subsurface soils suggest a low concentration of organic matter. However, due to the past agricultural production which have occurred on the subject site,this organic matter concentration is undoubtedly greater toward the soil surface. Organic matter serves two functions: First as a substrate for denitrifying bacteria and secondly as sites where NH4 ions can be "fixed" or bound. Since the soil moisture content becomes saturated at five feet below grade, anaerobic conditions are prevalent. Additionally, the soil pH is alkaline at 7.7 which promotes a favorable environment for denitrification. As referenced earlier, soil samples retrieved from the surface to four feet were analyzed for clay content, measured by the hydrometer method(ASTM D422). These samples were found to possess a clay content average of 62%. High clay content can translate to lower oxygen content(anaerobic conditions) of the subsurface soils. The cation exchange capacity (CEC)measures the potential for clay particles to adsorb NH4 ions, thus preventing nitrification(the conversion of NM ions to nitrate). However, not all types of clays have this capability. The analyzed CEC can be considered extremely high which is representative of the clay fraction present. From the data obtained from the Soil Analysis Report there are relatively favorable conditions for the denitrification process; a conservative estimate being a 30% reduction in NO3-N formation. The clogging mat which may form under the leachlines should theoretically remove another 20% of NO3-N. Although it is impossible to predict an exact concentration of NO3-N loading, a safe assumption is 50% of the total N loading will be as nitrate-nitrogen. Therefore, total NO3-N loading from the proposed project is projected to be 330 lbs. of NO3-N/yr. — 7 .01 Vaffey Ag Psearck