SR0084148_SSNL - Laserfiche WebLink

Home Browse Search

13 August 2021 AdvancedGeo Project No. 21-6530 AnEnWbCir Page 11 of 14 d 1Z • Home use concentration 45 mg/1-N (EHD standard). • The flow concentration of 9,000 mg/1-N gallon. 9.5. 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 30 percent was selected for the calculation based on the clayey soils existing at the site. 9.6. 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 = I x Nw (1-d) + R x Nb = (I+R) npfinitinn.c- 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 200 gpd (proposed system) x 365 days of proposed operation = 200 x 365 days _ 7.48 gallons per cubic foot = 9,759 cubic feet of wastewater. Does not account for evapotranspiration likely to occur. NW = Total nitrogen concentration of wastewater at 45 mg/L-N based on the average discharge. Accounting for the loss of mg/L-N in the septic tank at 15% = 45-15%= 38.25 and the loss from the biomat at 10% 38.25 - 10% = 34.425 mg/L-N.