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Table 3 illustrates that evapotranspiration exceeds precipitation, even when using higher rainfall data that exceeds normal rainfall data by 28% (10.33 in. vs. 13.18 in.). The Table also illustrates that during the months of December and January and possibly November and February, deep percolation potentially occurs. This data also illustrates a relatively high potential for there to be significant evapotranspiration from the primary disposal area. F. 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 well water supply in addition to the introduction of human 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 45 mg/L would require: 45 mg/L NH4-N x 7.1 mg CaCO3 = 320 mg/L alkalinity. The alkalinity in the domestic well water supply was measured at 77 mg/L. The alkalinity of the wastes is unknown, but the combination of the well water and wastes may not contribute sufficient alkalinity to promote nitrification, which must be supplied by the soil environment. III. NITRATE LOADING STUDY FINDINGS A. WASTEWATER CHARACTERISTICS AND FLOW VOLUME PROJECTIONS WASTEWATER CHARACTERISTICS The wastewater characteristics are anticipated to be those normally found in typical domestic or household systems. The scientific literature (Ref. 10) cites domestic wastewater nitrogen concentrations between 35 mg/L and 68 mg/L N. Due to dilution affects from bathing, laundry, dishwashing, etc., a concentration of 45 mg/L will be used in the calculations below. WASTEWATER FLOW VOLUME PROJECTIONS To determine nitrate -nitrogen loading from any project, wastewater flow volumes must be determined as accurately as possible. Domestic flow volume projections are typically approximated from the USEPA Onsite Wastewater Treatment Systems Manual, Pg. 3-4. However, for nitrate loading calculations, the EHD has specified wastewater flow projections from single family residential (SFR) structures to be calculated as follows: 100 gallons per day (gpd) for the first bedroom and 50 gpd for all subsequent bedrooms within the structure. Therefore, the flow volumes from the proposed three bedroom SFR are: 100 + 50 + 50 = 200 gpd. B. CALCULATED NITRATE -NITROGEN LOADING NLS§ 3.3, 3.4, 3.5, 3.6. The calculated nitrate -nitrogen impact to the soil and potentially to the groundwater is difficult to determine due to the large number of variables involved and unknown at this time. These include: 1.) Variability in wastewater flows, nitrogen concentrations and dilution affects that may occur, 2.) Impact from upgradient nitrate sources, 3.) Changes in groundwater directional flow and elevation, 4.) Denitrification potential within the soil environment and within the confined and/or unconfined aquifers, and 5.) Landscape grass uptake of nitrogen. 5 Chesney Consulting