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Wastewater Characteristics Blackwater will originate from toilets and graywater from showers, laundry, teeth brushing, dishwashing and hand washing. Additional wastewater constituents may consist of other liquids to the system, such as coffee, juices, etc. The scientific literature cites nitrogen concentrations in domestic septic effluent typically ranging from 17 mg N/L for basins, sinks, etc. to 140 mg N/L for toilet wastes. Therefore, taking a composite of these values, a nitrogen concentration of 62 mg N/L within the septic effluent will be used to calculate nitrate-nitrogen loading for this project (See Kaplan - Septic Systems Handbook, Pg. 147). 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 variables unknown at this time. These include: 1.) Impact from upgradient agricultural and septic system sources, 2.) Variability in wastewater flows, nitrogen concentrations and dilution effects from stormwater recharge, 3.) Changes in groundwater directional flow and elevation, 4.) Denitrification potential within the loam and clay soil fractions, and within confined and/or unconfined aquifers. The Hantzsche/Finnemore Formula is used below to predict the average resultant concentration of nitrate-nitrogen in effluent recharge water. As calculated below, the property has been assessed on a total areal loading basis correlated with the total projected yearly wastewater flow volumes calculated above. These two factors primarily estimate the average resultant concentration of nitrate-nitrogen in the recharge water. This concentration should not exceed 10 ppm nitrate-nitrogen (45 ppm as nitrate). Nitrate-nitrogen loading calculations: INw (1 - + R Nb Nr = (I+R) Where: Nr = Resultant average concentration of nitrate-nitrogen in recharge water - (ppm NO3-N) I = Volume rate of wastewater entering the soil averaged over the gross developed area in ac-ft Nw = Total nitrogen concentration of wastewater in mg N/L d = Fraction (%) of nitrate-nitrogen combined loss in the high clay content soil due to: 1.) Prevention of nitrification and 2.) The denitrification of nitrate molecules that may form. R = Estimated Annual Rainfall Recharge in ac-ft Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences (ppm NO3-N). Page -5- Chesney Consulting