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FFThepecifies that each bedroom has the potential for two people,therefore an ADF of 140 py. As referenced,the existing house has four bedrooms and the proposed second unit ill have three bedrooms, for a total of seven bedrooms. Therefore, total flow volume = 7 x 140= 980 gallons wastewater/day. 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). 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 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 clay soil environment and within the confined and/or unconfined aquifers. The Hantzsche/Finnemore Formula is used in this report 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). Calculated nitrate-nitrozen loading from the entire subject property: INwLL- _dA+ RNb 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 inches per yr Nw = Total nitrogen concentration of wastewater in mg N/L d = Fraction(%)of nitrate-nitrogen loss due to denitrification in the soil R = Average recharge rate of rainfall - inches per yr NLS§3.2 Nb = Background nitrate-nitrogen concentration of rainfall recharge, exclusive of wastewater influences (ppm NO3-N), Page 5 of 12 Chesney Consulting