SR0084415_SSNL - Laserfiche WebLink

Home Browse Search

01 November 2021 AdvancedGeo An EmploycaOwntd Company Project No. 21-6435 M,. V Page 2 of 3 • Commercial volume = 120 gpd. • Commercial concentration 85 mg/1-N (EHD standard). • The flow concentration of 10,200 mg/1-N gallon. DENITRIFICATIONS CAUSED BY SOILS The process of denitrification is important when utilizing subsurface septic lines and regularly occurs in the soil within the leach fields where bacteria utilize oxygen in the nitrate to release nitrogen gas out to the atmosphere. The denitrification process is controlled by waste concentrations, soil type, annual rainfall, pH of the soils, total organic concentration of the soil (TOC) and exposure time to nitrogen. The soils with a high or moderate clay content, higher organic content, high pH and adequate soil moisture denitrify the concentrations by approximately 30 percent and less desirable soils with more sands and faster percolation rates (less moisture and clay content) denitrify only about 10 percent. A denitrification factor of 25 percent was selected for the calculation based on the silty sand and loam soil existing at the site. MASS BALANCE OF NITROGEN LOADING The EHD requires the user to consider all potential sources identified for wastewater generation. Further, the EHD supports the use of Hantzsche/Finnemore, or other appropriate formula/model to calculate a mass of nitrogen loading. RESIDENTIAL: The Hantzsche / Finnemore (Nr) equation for residential home application: Nr = IxNw (1-d) + RxNb + (I+R) Definitions: Nr = The average concentration of nitrate-nitrogen in the recharged wastewater parts per million of nitrate-nitrogen. I = Volume rate of wastewater entering the soil averaged over the gross developed area (acres) in inches per year. The total wastewater volume for proposed project will be 120 gpd x 260 days of proposed operation = 120 x 260 days - 7.48 gallons per cubic foot = 4,171 cubic feet of wastewater. Does not account for evapotranspiration likely to occur. NW = Total nitrogen concentration of wastewater at 85 mg/L-N based on the average discharge.