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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 two-bedroom home is estimated to produce 150 gpd of <br /> wastewater. A typical residential concentration of 35 mg/L of nitrate as N was selected <br /> for the proposed residence (Crites and Tchobanoglous, 1998). <br /> The estimated sewage flow rates for various uses are available from a number of <br /> references. To select an appropriate use value for the employee on the Site, Live Oak <br /> reviewed the San Joaquin County On-Site Wastewater Treatment Systems Standards <br /> (2017), Crites and Tchobanoglous (1998), and US EPA (1980). Crites and <br /> Tchobanoglous indicate that 13 gallons per day for each employee is typical for an <br /> office or industrial worker; this rate was used for the facility's employee. The nitrate as <br /> 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 166.7 gallons per day <br /> (gpd). Through the use of a weighted average, the average concentration of all the <br /> different effluent flows and concentrations was determined to be 40.0 mg/L-N at 166.7 <br /> gallons per day. Please see the following tables: <br /> Table 4. Average Daily Flow Calculation <br /> Use Units Rate Subtotal Reduction Average Daily <br /> Flow <br /> Residence 2 bed 150 gal/2BR/day 150 gpd None 150 gpd <br /> rooms <br /> Employee 1 13 gal/person/day 13 gpd 6/7, 12/8 16.7 gpd <br /> Total 166.7 gpd <br /> Reduction factors convert calculated flow into average daily flow over a year. The factors 6/7 refers to days per <br /> week, and the factor 12/8 refers to hours worked versus a standard workday. No reduction is used for a residence <br /> since it is continuously occupied. <br /> LOGE 2110 Page 11 <br />