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From the anticipated wastewater characteristics described above, the nitrogen emanating from the project may be at a higher concentration than what would normally be found in a typical domestic or household system. This can be attributed to the lack of a dilution effect that graywater from showers, laundry, etc. would provide. The scientific literature cites nitrogen concentrations in residential septic effluent typically ranging from 17 mg NIL for basins, sinks, etc. to 140 mg NIL for toilet wastes. Therefore, considering a 70/30 percent usage for toilet water volume and sink water volume, respectively, a value of 103 mg NIL of septic effluent will be used to calculate nitrate-nitrogen loading for this project. B. PREDICTED NITRATE-NITROGEN LOADING The calculated or estimated nitrate-nitrogen impact to the soil and ultimately to the groundwater is difficult to determine due to the number of variables involved. These variables include 1.)past installation methods of the on-site septic systems, 2.) future replacement methods for failed systems, 3.) impact from upgradient nitrate sources, 4.) variability in wastewater flows, nitrogen concentrations and dilution effects, 5.) changes in groundwater directional flow and elevation, G.) denitrification potential and landscape uptake of nitrogen, and 7.) proposed installation of a wastewater treatment system to mitigate nitrate impact. The following nitrate-nitrogen loading calculations are presented under two scenarios. The first loading projections are based on using conventional septic systems (septic tank and Ieachfields) throughout the entire, completed project. This will present comparison data between the use of traditional systems, versus treating a percentage of the total wastewater originating from the project as a whole. The second loading calculations factor in an anticipated reduction in loading through the use of an on-site wastewater treatment system and utilization of landscaping as a nitrogen uptake medium. This estimated nitrogen loading will be added to the remaining projected loading from the conventional systems north of Carmelo Avenue. There are various scientific methods to estimate nitrate-nitrogen loading. This report uses the Hantzsche/Finnemore Formula to predict the average concentration of nitrate-nitrogen in effluent recharge water. PREDICTED NITRATE-NITROGEN LOADING FROM A COMPLETELY BUILT- OUT PROJECT USING CONVENTIONAL SEPTIC SYSTEMS: HANTZSCHEIFINNEMORE EQUATION INW Q - d, +R Nb Nr (I+ R) Chesney Consulting