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Wastewater Flow Volume Projection f To determine nitrate-nitrogen loading from the project,wastewater flow volumes must be determined as accurately as possible. Typically, loading projections are based on the maximum or total number of employees and customers who may potentially use the toilet/sink, etc. on a workday basis. Several variables are involved in estimating wastewater flows from a facility. Wastewater flow volume projections for facilities in unsewered areas have been historically and typically calculated under numerous guidelines and scenarios, as illustrated in the following list: 1. Published Data in the San Joaquin County Sewage Standards and scientific literature. 2. Number of bathroom fixtures (bathroom use per capita) for a facility. 3. Number of parking spaces for a facility. 4. Maximum number of people(e.g., employees, customers, etc.) for a facility. 5. Historical wastewater flow data from an existing facility. 1. The San Joaquin County Sewage Standards assigns 15 gallons per person for Industrial Buildings with no food cafeteria, 10 gallons per vehicle served for service stations, or 30 gallons per person for day workers at offices. 2. The number of bathroom fixtures(toilets)is assumed to be one Men's and one Women's. The Sewage Standards assign 150 gallons per toilet fixture(employee/public use) for Retail Markets. Since there are no project details at present, the only applicable criteria at this time is assigning 15 gallons per person for an Industrial/Commercial Building so that a total volume of wastewater ow can be obtained_which can then be correlated with the maximum number of people the proper can support. Wastewater Flow Characteristics It is assumed there will be no cooking, or food production in any future building. Therefore, there should be no highly concentrated organic loading. The characteristics of the wastewater flow will be predominately blackwater from toilets, with a comparatively small volume of graywater from sinks, or other sources of graywater. Additional wastewater constituents may consist of coffee, juices or other similar type liquids to the system. No industrial or commercial chemicals, solvents, etc. are to be introduced into the septic system. From the anticipated wastewater characteristics described above, the nitrogen emanating from the project may be at a higher concentration than what would normally be found in a typical domestic or household system. This can be attributed to the lack of a dilution effect that graywater from showers, laundry, and dishwashing would provide from a household. The scientific literature cites nitrogen concentrations in residential septic effluent typically ranging from 17 mg NIL for basins, sinks, etc. to 140 mg NIL for toilet wastes. Therefore, considering a 70130 percent usage for toilet water volume and sink water volume, respectively, a value of 103 mg NIL of septic effluent will be used to calculate nitrate-nitrogen loading for this project. A value of 66 mg NIL is typically used for residential calculations, as indicated in the scientific literature. i 10 Chesney Consulting