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20 November 2020 AdvancedGeo Project No. 20-6205 AnEmployte-OwneQCompany Page 11 of 14 ETo between 2014 and 2019. The estimated deep percolation (R) is 3.69 inches (Appendix E). 9.3. CURRENT ON-SITE SOURCES OF NITRATE Septic systems, rainfall and agriculture are sources of nitrates (fertilizers) present on or around the property. There are currently no onsite sources of nitrates at the subject property. 9.4. FUTURE ON-SITE SOURCES OF NITRATE The future site usage includes the addition of residence with four bedrooms for residential use. Residential use includes showering/bathing, clothes washing, cooking, and hand washing. The reasonable or maximum usage of wastewater for the four-bedroom home is 100 gallons per day (gpd) for the first bedroom and 50 gpd for each additional bedroom for a total of 250 gpd. The total nitrate-nitrogen (NO3_N) average concentrations in domestic waste ranges between 20 to 85 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 residential flow is proposed as the following: • Residential volume 250 gpd. • Home use concentration 45 mg/1-N (EHD standard). • The flow concentration of 11,250 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 to 40 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 alluvium soil existing at the site.