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B. Calculation of Alkalinity Requirement for Nitrification The nitrate-nitrogen loading calculations below 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 and the introduction of wastes to the wastewater. As referenced,nitrification consumes approximately 7.1 mg of alkalinity for every milligram of ammonia-nitrogen(NH4-N) oxidized. Water chemistry for the new domestic well for the project will probably be similar to the sampled domestic well which serves the Cunha facility. Nitrification of the average Total Nitrogen(TN) concentration of 88 mg/L is determined in. Section IV below. Considering that ammonium typically composes 70-90% of the total nitrogen in septic tank effluent: 88 mg/L x 80% =70 mg/L NH4-N x 7.1 mg CaCO3 = 500 mg/L alkalinity required. Therefore the alkalinity in the domestic water supply is deficient if the TN will be approximately 88 ppm, and nitrification may be inhibited. C. Mounding Analysis Reference is made to the encountered groundwater table at 11 feet under the existing grade of the proposed filter bed. This shallow groundwater table may induce a phenomenon known as the mounding effect. An analytical procedure found in Small and Decentralized Wastewater Management Systems is used below to predict the long-term maximum rise of the mound: h= H +Zm-2 where: h=distance from boundary to mid-point of the long-term mound, in ft H=height of stable groundwater table above impermeable boundary, in ft Zm= long-term maximum rise of the mound, in ft Substituting known and estimated values for the variables,we find the following: H= From the attached well log for the on-site well drilled in 1995, a clay layer exists from 36 to 39 ft below grade. Therefore, since the water table is at 11 ft, and using 36 ft as the boundary, H =25 ft. Long-termmaximum rise is estimated at 4 ft. Therefore, h=25 +4-2 = 15 Zm 1 C 1 (4 )n 1 Kh)a5. ' t 1-0.5n where: Q=maximum daily flow in ft3/day A=area of disposal field in ft' C =mounding equation constant L=length of disposal field in ft K=horizontal permeability of soil in friday n=mounding equation exponent LL Page -5- Chwxy Consufting