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C75.5Calculation of Alkalinity Requirement for Nitrification All 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. As referenced,nitrification consumes approximately 7.1 mg of alkalinity for every milligram of ammonia-nitrogen (NH4-I) oxidized. Effluent sampled from domestic and commercial septic tanks typically exhibit higher alkalinity than groundwater, with domestic well water from deeper aquifers generally having a much lower alkalinity than shallower groundwater from shallow wells. Nitrification of the average Total Nitrogen concentration of 87 mg/L as used in the calculations would require the following: Assume that of the 87 mg/L Total Nitrogen, 70% is in the ammonium form: 87 x 70%= 61 NH4 N x 7.1 mg CaCO3 =432 mg/L alkalinity. As noted in Table 6, the J alkalinity from the domestic well was 220 mg/L. Consequently, the anticipated wastewater must contribute approximately 210 mg/L of alkalinity for nitrification to readily proceed. 6. PRELIMINARY WASTEWATER DISPOSAL OPERATIONAL CRITERIA The following information describes the preliminary details of the wastewater disposal system for the different types of commercial business within the subject complex. Since the entire project is in the initial phases of planning, several facets of the project are subject to change;which in tum would cause changes to the wastewater disposal system ultimately installed. Septic and Grease Interceptor Tanks SSS§3.7 Influent from each of the different business within the Complex must flow either by gravity or low pressure piping systems into septic tanks. Food wastes from the restaurants must flow into interceptor tanks, commonly referred to as grease traps. These tanks will provide the preliminary treatment of the influent from all of the businesses. The volume of tanks required is primarily dependant upon hydraulic residence time, although other factors may also be considered on a site-specific basis. 1 6.2 Septic Tank Volume Hydraulic Detention Time Example - Completely Built Out j Project Consisting of both Phase 1 and Phase 2 Detention Time=70,000 gal septic tank capacity x 0.70 (30%volume lost to sludge/scum accumulation) 2 (Peaking Factor) x 25,830 gals/day Detention Time= 1.0 day. The minimum acceptable detention time is 1.0 day. Septic Tank Volume Hydraulic Detention Time Example - Phase 1 Exclusively 1 Detention Time= 35,00 gal septic tank capacity x 0.70 (30%volume lost to sludge/scum accumulation) 2 (Peaking Factor) x 12,000 gals/day Detention Time = 1.0 day. Page -22- Chesney Consulting