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• APPENDIX 6: NITRATE LOADING CALCULATION, PHASE 5 The following discussion utilizes maximum customer numbers from the full build- out (Phase 5) of the project, as provided by Ms. Peterson. Quantity and Quality of Domestic Wastewater Ms. Peterson indicated that the stables will be open seven days per week. Monday through Friday, six employees will be present. Saturday, five employees will be present, and Sunday, four employees will be present. Three of the employees who are present all week live in the houses on the Site; as a result, they are excluded from the calculation below. An estimated 12 customers per day are anticipated Monday through Friday, 50 on Saturday, and 20 on Sunday. The value for Saturday includes customers attending horse shows that will be held once of twice per month; no other special events are planned. Ms. Peterson indicated that the main house on the Site has four bedrooms, while the caretaker's house has three bedrooms. The estimated sewage flow rates for various uses are available from a number of references. The uses presented below were guided by the San Joaquin County On-Site Wastewater Disposal Standards (2016), Crites and Tchobanoglous • (1998), and US EPA (1980). The references indicate that 13 gallons for each employee is typical for an office or industrial worker and 5 gallons per visitor is typical for guests at a visitor center; these rates were used for the stable's employees and customers (Crites and Tchobanoglous, 1998). Crites and Tchobanoglous (1998) list a typical flow rate of 50 to 70 gallons per person per day for an individual residence. The San Joaquin County Enviromental Health Department has indicated that maximum flow and double occupancy within each bedroom should be considered for the nitrate loading assessment; as a result, a value of 140 gallons per bedroom per day has been selected (personal communication, January 6, 2017). The estimated flow values discussed here should not be used for the design and sizing of the septic system. The design and sizing of the septic system should utilize the San Joaquin County Environmental Health Department On-Site Wastewater Disposal Standards which incorporate peak and surge flow factors. The estimates used in the On-Site Wastewater Disposal Standards may be greater than those discussed here. The nitrate as nitrogen (N) concentration of the customer and employee use is estimated to be 85 mg/L (US EPA, 1980). A typical residential concentration of • LOGE 1820 Page 6-1