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33503 S Koster Road Project No.2021-00073 Page 17 <br /> (100 gallons per 1St bedroom per <br /> 1 100 365 day x 1 bedroom x 365 days)/ <br /> Existing 365 days= 100 gal <br /> Main House-3 <br /> Bedroom (50 gallons per bedroom per day <br /> 2 50 365 x 3 bedrooms x 365 days)/365 <br /> days= 100 gal <br /> (100 gallons per 1St bedroom per <br /> 1 100 365 day x 1 bedroom x 365 days) / <br /> Proposed 365 days= 100 gal <br /> 2nd Unit Dwelling-2 <br /> Bedroom (50 gallons per bedroom per day <br /> 1 50 365 x 2 bedrooms x 365 days)/365 <br /> days=50 gal <br /> *Based on EHD request with previous studies <br /> TOTAL AVERAGE GALLONS PER DAY 350 gallons <br /> For the site, the total daily toilet use contributing wastewater quantity, considering the <br /> existing and planned residential dwellings is 350 gallons per day. The average total nitrogen <br /> concentration of domestic wastewater is normally considered to be 20-85 mg/L-N with 35 <br /> to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). Based on EHD request with <br /> previous studies, it is estimated that residential domestic wastewater concentration will be <br /> approximately 35 mg/L-N. <br /> 5.4.2 Denitrification Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain <br /> bacteria utilize the oxygen in the nitrate (NO3) and release nitrogen gas (N2) to the <br /> atmosphere. Denitrification is expressed as a percentage, and the normally accepted range <br /> is 10 percent to 35 percent. Soils with higher clay content, moist soil conditions, high pH, <br /> and organic material denitrify by about 35 percent, and soils with high sand content and fast <br /> percolation rates are estimated to denitrify at a lower rate, about 10 percent to 15 percent. <br /> Based on the clayey loam soil types for the subject property, denitrification is estimated to <br /> be 30 percent. <br /> 5.5 Nitrate Loading <br /> A nitrate loading scenario was performed to determine the impact from the proposed <br /> project. The scenario utilizes the variables discussed previously which represent the <br /> estimated conditions and uses associated with this project. The following table presents a <br /> summary of the nitrate loading calculation for the parcel. <br /> Petralogix Engineering,Inc. <br /> 26675 BruelIa Road,Galt,Ca 95632 <br /> (209)-40o-5729 <br /> www.petralogix.com <br />