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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Schuler Property . Tracy, California <br /> May 30, 2019 Terracon Project No. NA197026 <br /> Table 8. <br /> Potential Quantity of Effluent. <br /> Average Average <br /> Number of Number of Effluent days of Average Daily Flow <br /> Category People per Quantity per <br /> Bedrooms Buse per (gpd*) <br /> Bedroom Person <br /> (gpd") year <br /> Existing (4 bedrooms x 2 people per bedroom <br /> Residence 4 2 70 365 x 70 gal. per day x 365 days per <br /> year)/365 days per year=560 gpd <br /> Proposed 3 bedrooms x 2 people per bedroom <br /> Mobile Home 3 2 70 365 x 70 gal. per day x 365 days per <br /> year)/365 days per year=420 gpd <br /> Potential Average Daily Flow 980 gallons per day <br /> *gpd -gallons per day <br /> Based on a review of Table 8, the estimated potential sewage flow rate for the existing four <br /> bedroom residence is 560 gallons per day. The proposed three bedroom mobile is estimated to <br /> add an additional 420 gallons per day for a combined total of 980 gallons per day. <br /> The average total nitrogen concentration of domestic wastewater is normally considered to be 20 <br /> to 85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). It is estimated <br /> that commercial use will have higher concentrations of total nitrogen when compared to residential <br /> use. For the purposes of the nitrate loading estimate, it is estimated that the average <br /> concentration for total nitrogen in wastewater for the project is approximately 45 mg/L-N over the <br /> long term. <br /> 2.3.4.2 Denitrification Estimate <br /> Denitrification is an important process which occurs within the leach field whereby certain bacteria <br /> utilize the oxygen in the nitrate (NO3) and release nitrogen gas (NZ) to the atmosphere. <br /> Denitrification is expressed as a percentage, and the normally accepted range is 10 percent to 35 <br /> percent. Soils with higher clay content, moist soil conditions, high pH, and organic material <br /> denitrify by about 35 percent, and soils with high sand content and fast percolation rates are <br /> estimated to denitrify at a lower rate, about 10 percent to 15 percent. <br /> Based on the results of the shallow soil borings, the proposed new leach field is expected to be <br /> located within silty sandy soil with clayey soils between 6.5 to 10 feet bgs; therefore, a <br /> denitrification estimate of 35 percent was selected. <br /> Responsive ■ Resourceful ■ Reliable 15 <br />