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Discussion on the Alkalinity Requirement for Nitrification The nitrate-nitrogen loading calculation 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 well water, in addition to the introduction of wastes. Nitrification consumes approximately 7.1 mg of alkalinity for every mg of ammonia- nitrogen(NH4-N) oxidized. Nitrification of the average Total Nitrogen(TN) concentration of 62 mg/L, as determined below, would require: 62 mg/L NH4-N x 7.1 mg CaCO3 =440 mg/L alkalinity. The alkalinity in groundwater was determined to be 106 mg/L. Therefore, soil alkalinity and alkalinity from wastes must provide a significant alkalinity concentration for nitrification to occur. SURFACE WATER INFORMATION Climatic Data: Rainfall versus Evapotranspiration NLS§3.2. It is generally and scientifically accepted that when precipitation exceeds evapotranspiration(Eto), deep percolation of surface rainwater may occur. Evapotranspiration refers to water evaporation that takes place both at the soil surface and transpiration by plants. The following Table illustrates rainfall and evapotranspiration for the Tracy area, which is closest data available. Precipitation data was obtained from the Soil Survey of San Joaqui Coun1y. The conservative "2 years in 10"data was used and not the "average rainfall"data Evapotranspiration data was obtained from the California Irrigation Management Information System(CIMIS): TABLE 3 PRECIP TATION AND Eto DATA FOR TRA Y, CA Month 2 Yeari 10 will have m r Eto Average Potential Dee precipi tion than: (in/� = (in/day) Percolation (in mo) January 2.93 1.55 0.05 1.38 February 2.21 2.24 0.08 -- March 2.38 3.72 0.12 -- April 1.51 5.10 0.17 May 0.71 6.82 0.22 - June 2.09 7.80 0.26 - July 0.28 8.68 0.28 - August 1.05 7.75 0.25 -- September 1 0.84 5.70 0.19 -- Chesney Consulting