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18340 E Rodeo Drive Project No.2018-00037 Page 16 <br /> Per San Joaquin County Environmental Health requested guidelines based on previous <br /> nitrate loading studies, an average daily flow of 140 gallons per bedroom per day is <br /> estimated for the site. The following table presents the nitrate contributing septic <br /> wastewater flowrates anticipated for the site. <br /> Table 2. <br /> Typical Quantity of Effluent <br /> Average <br /> Quantity Days of <br /> Category Total per Use per Average Daily Flow <br /> Bedrooms Bedroom Year Per Facility <br /> per Day* <br /> al <br /> Current Residence (140 gallons per bedroom per day <br /> Main House-3 3 140 365 x 3 bedrooms x 365 days)/365 <br /> Bedroom days=420 gal <br /> Current Residence (140 gallons per bedroom per day <br /> Secondary House-2 2 140 365 x 2 bedrooms x 365 days)/365 <br /> Bedroom days=280 gal <br /> Proposed Residence (140 gallons per bedroom per day <br /> 2nd Unit Manufactured 4 140 365 x 4 bedrooms x 365 days)/365 <br /> Home-4 Bedroom IL days=560 gal <br /> *140 gallons per bedroom per day is based on EHD request from previous studies <br /> TOTAL AVERAGE GALLONS PER DAY 1,260 gallons <br /> For the site, the total daily toilet use contributing wastewater quantity is 1,260 gallons per <br /> day. The average total nitrogen concentration of domestic waste water is normally <br /> considered to be 20-85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and <br /> Tchobanoglous, 1998). During previous studies, EHD has requested a wastewater <br /> concentration of 35 mg/L-N,therefore, it is estimated that residential domestic wastewater <br /> concentration will be approximately 35 mg/L-N. <br /> 4.4.2 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 /> The Cometa soil is primarily a sandy clay loam, with moderate pH levels and low <br /> permeability; the Tokay soil is therefore estimated to denitrify at approximately 30%. The <br /> Petralogix Engineering,Inc. <br /> 26675 Bruella Road,Galt,Ca 95632 <br /> (209)-400-5729 <br /> www.petralogix.com <br />