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30 June 2022 AdvancedGeo <br /> Project No. 22-6900 An Employee-Owned Company <br /> Page 12 of 15 <br /> The total nitrate-nitrogen (NO3_N) average concentrations in domestic waste ranges <br /> between 20 to 85 mg/1-N with an average of 45 mg/1-N when washing and sanitation is <br /> considered. <br /> The weighted average calculation for total nitrogen concentrations for onsite residential <br /> flow is proposed as the following: <br /> • Residential volume 200 gpd. <br /> • Home use concentration 45 mg/1-N (EHD standard). <br /> • The flow concentration of 9,000 mg/1-N gallon. <br /> 9.5. DENITRIFICATIONS CAUSED BY SOILS <br /> The process of denitrification is important when utilizing subsurface septic lines and <br /> regularly occurs in the soil within the leach fields where bacteria utilize oxygen in the <br /> nitrate to release nitrogen gas out to the atmosphere. The denitrification process is <br /> controlled by waste concentrations, soil type, annual rainfall, pH of the soils, total organic <br /> concentration of the soil (TOC) and exposure time to nitrogen. The soils with a high or <br /> moderate clay content, higher organic content, high pH, and adequate soil moisture <br /> denitrify the concentrations by approximately 30 percent and less desirable soils with <br /> more sands and faster percolation rates (less moisture and clay content) denitrify only <br /> about 10 percent. <br /> A denitrification factor of 30 percent was selected for the calculation based on the sandy <br /> loam and clay soil existing at the site. <br /> 9.6. MASS BALANCE OF NITROGEN LOADING <br /> The EHD requires the user to consider all potential sources identified for wastewater <br /> generation. Further, the EHD supports the use of Hantzsche/Finnemore, or other <br /> appropriate formula/model to calculate a mass of nitrogen loading. <br /> RESIDENTIAL: <br /> The Hantzsche / Finnemore (Nr) equation for residential home application: <br /> Nr = I x Nw (1-d) + R x Nb = (I+R) <br /> Definitions: <br /> Nr = The average concentration of nitrate-nitrogen in the recharged wastewater parts per <br /> million of nitrate-nitrogen. <br /> I = Volume rate of wastewater entering the soil averaged over the gross developed area <br />