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18 September 2020 AdvancedGeo Project N o. 20-6116 An Employee-Owned Company Page 12 of 15 'Zo M N 9.4. FUTURE ON-SITE SOURCES OF NITRATE Following the parcel boundary change, the existing septic system located at the southwest residence on Parcel 1 will be located on the subject property and will be a future on-site source of nitrates. The future site usage includes a 4,398-square foot residence with two-bedrooms. Residential use includes showering/bathing, clothes washing, cooking, and hand washing. The reasonable or maximum usage of wastewater for a two-bedroom home is 100 gpd for the first bedroom and 50 gpd for each additional bedroom for a total of 150 gpd. The total nitrate-nitrogen (NO3_N) average concentrations in domestic waste ranges between 20 to 85 milligram total nitrogen liter (mg/1-N) with an average of 45 mg/1-N when washing and sanitation is considered. The weighted average calculation for total nitrogen concentrations for onsite wastewater flow is proposed as the following: • Residential volume = 150 gpd. • Home use concentration 45 mg/1-N (EHD standard). • The flow concentration of 6,750 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 25 percent was selected for the calculation based on the loamy sandy soil 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.