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first bedroom and 50 gpd for each additional bedroom; additional residences should be <br />calculated in the same manner (personal communication, March 4, 2020). <br />Using this method, the one -bedroom home is estimated to produce 100 gpd of <br />wastewater. A typical residential concentration of 35 mg/L of nitrate as N was selected <br />for the existing residence (Crites and Tchobanoglous, 1998). <br />The estimated sewage flow rates for various uses are available from a number of <br />references. To select appropriate use values for the employee and customers of the <br />Site, Live Oak reviewed the San Joaquin County On -Site Wastewater Treatment <br />Systems Standards (2017), Crites and Tchobanoglous (1998), and US EPA (1980). <br />Crites and Tchobanoglous indicate that 13 gallons per day for each employee is typical <br />for an office or industrial worker, and 5 gallons per day per user is typical for a public <br />lavatory; these rates were used for the facility's employees and customers. The nitrate <br />as nitrogen (N) concentration of the employee use is estimated to be 85 mg/L (US EPA, <br />1980). <br />The estimated flow values discussed here should not be used for the design and sizing <br />of the septic system. The design and sizing of the septic system should utilize the San <br />Joaquin County Environmental Health Department On -Site Wastewater Treatment <br />Systems Standards, which incorporates peak and surge flow factors. The estimates <br />used in the On -Site Wastewater Treatment Systems Standards may be greater than <br />those discussed here. <br />The maximum average daily flow for the Site was estimated to be 320.4 gallons per day <br />(gpd). Through the use of a weighted average, the average concentration of the <br />different effluent flows and concentrations was determined to be 69.4 mg/L-N at 320.4 <br />gallons per day. Please see the following tables: <br />Table 4. Average Daily Flow Calculation <br />Use <br />Units <br />Rate <br />Subtotal <br />Reduction <br />Average Daily <br />Flow <br />Residence <br />1 bed <br />100 gal/1 BR/day <br />100 gpd <br />None <br />100 gpd <br />room <br />Employees <br />3 <br />13 gal/person/day <br />39 gpd <br />5/7, 12/8 <br />41.8 gpd <br />Customers <br />50 <br />5 gal/person/day <br />250 gpd <br />5/7 <br />178.6 gpd <br />Total <br />320.4 gpd <br />Reduction factors convert calculated <br />flow into average daily <br />flow over a year. <br />The factor 5/7 refers to days per week, <br />and 12/8 refers to hours worked <br />versus a standard workday. No reduction is used for <br />a residence since it is <br />continuously occupied. <br />LOGE 2142 Page 12 <br />