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04 November 2019 AdvancedGeo <br /> AGE Project No. 19-4819 Environmental <br /> Page 3 of 5 n.N'V <br /> 9.4. FUTURE ON-SITE SOURCES OF NITRATE <br /> The future site usage includes the addition of a 2,100-square foot residence with two <br /> bedrooms and two bathrooms for residential use. Residential use includes <br /> showering/bathing, clothes washing, cooking, and hand washing. The reasonable or <br /> maximum usage of wastewater for the two-bedroom mobile home is 140 gpd per bedroom <br /> for a total of 280 gpd. The total nitrate-nitrogen (NO3_N) average concentrations in <br /> domestic waste ranges between 20 to 85 milligram total nitrogen liter (mg/1-N) with an <br /> average of 45 mg/1-N when washing and sanitation is considered. <br /> The weighted average calculation for total nitrogen concentrations for onsite residential <br /> flow is proposed as the following: <br /> • Residential volume 280 gpd. <br /> • Home use concentration 45 mg/1-N (EHD standard). <br /> • The flow concentration of 12,600 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 25 percent was selected for the calculation based on the silty <br /> clayey fine-grained sand 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 />