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F7NLS§ RATE SOURCES AND CALCULATED IMPACT TO GROUNDWATER iables that influence nitrate loading include: 1.) Variability in wastewater flow ngths, 2.) Impact from upgradient nitrate sources, 3.) Changes in groundwater directional flow and elevation, 4.)Nitrification, denitrification and other chemical reaction potential within the underlying soil, and 5.) Rainfall stormwater recharge and dilution effects. The following calculations predict the nitrate-nitrogen-loading from the built-out project by using formulas from two researchers for comparison purposes with regard to loading potential. These top researchers include the Hantzsche/Finnemore Equation, and the Crites/Tchobanoglous Formula obtained from Small and Decentralized Wastewater Management Systems. The following criteria were used as primary data to arrive at the calculated loading: 1.) The Average Daily Flow based on the parameters described on Pages 1-3 of the Phase II Report, 2.) Using a Total Kjeldahl Nitrogen (TKN) concentration of 25.3 mg/L as derived below, and 3.) Taking the entire project area of 2.81 acres into consideration. Only TKN concentrations are taken into consideration, which exclude nitrate concentrations since nitrate does not typically exist in septic/grease tanks. The assumption is made that all TKN nitrifies to nitrate. To determine the total nitrate-nitrogen impact potential from the project,the anticipated nitrogen concentration from each of the sources must be calculated. Beginning with the TKN content from the last(assumed) grease interceptor tank, a TKN concentration of 52.7 mg/L was determined. The TKN concentration from the last(assumed) conventional septic tank was found to be 66.7 mg/L. A number of design features and operational changes will be implemented when the new system is installed. These include extreme capture of all food products, and oil and grease before dishwashing for solid waste disposal, larger tankage and therefore longer hydraulic retention times, conducive dishwashing chemicals,and effluent filtration. Consequently, it is anticipated that the TKN concentration from the kitchen wastewater flows will be decreased by at least one-half to 26.4 mg/L. These two TKN concentrations will ultimately commingle within the second chamber of the conventional tank. Taking the sum of the concentrations and dividing by 2 to reduce the volume back to one liter, we find: 26.4 + 66.7 =46.5 mg/L TKN. It is assumed the TKN concentration from the ARCO septic tank will be a low concentration in comparison to the Restaurant tank; on the order of one-quarter(16.7 mg/L) because of an anticipated lower volume of solid wastes. Effluent from the ARCO tank will gravity flow to the first polishing tank to commingle with the effluent from the Restaurant. Now we have a theoretical TKN concentration (assuming relatively equal volumes from the two sources) in the first compartment of the polishing tank of: 46.5 mg/L+ 16.7 mg/L-2 = 31.6 mg/L. At a May 8, 2003 Symposium"Onsite Wastewater Treatment-Nitrogen Removal,"Dr. Stuart Oakley of Chico State University states that"approximately 20%of the total nitrogen generated is removed in the septic tank." A 20%nitrogen reduction will be used instead of 40%(for two polishing tanks). This gives a final projected TKN concentration of 25.3 mg/L(31.6 x 1-0.2=25.3 mg/L)before the effluent is pumped from the second polishing tank to the soil disposal area. This concentration is used in the calculations below. Page 5 of I 1 Chesney Consulting