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� QO,* December 1,2004 W t-G NOA Project Number. E040117A j/.3 Current On-Site Sources of Nitrate Current on-site sources of nitrate include the current septic system for the residence and mini- mart. /3.4 Future On-Site Sources of Nitrate 3.4.1 Quantity and Quality of Domestic Wastewater From Proposed Project The following discussion is for determining the long-term waste water flow generated from the proposed residences for the nitrate loading analysis and should not be used for septic system design purposes. Typically, use estimates for the sizing of septic systems include a peak use factor, whereas the numbers discussed here are based on long-term averages. For Parcel 1, a three (3) bedroom mobile home, and the mini-mart. The three (3) bedroom mobile home is presumed to be occupied by up to four people over the long term. The mini-mart is open 13 hours a day (two shifts), 7 days a week, with usually two employees present per shift. Four workers per day total. On average, 10 customers Wr day use the restroom. These is no room for a second dwelling unit on this property. For Parcel 2, it is likely that a three bedroom home will be built. A three bedroom house is 3e presumed to be occupied by up to four people over the long term. A second dwelling unit, occupied by a potential three people, could be placed on the lot as well. Therefore, a total of W seven people per parcel will be used to calculate the residential septic tank usage for parcel 2. The estimated sewage flow rates for use categories are available from a number of references. The uses presented below were guided by the San Joaquin County On-Site Wastewater Disposal Standards(2003),Crites and Tchobanoglous(1998), and EPA(1980). The San Joaquin County On-Site Wastewater Disposal Standards does not provide a flow rate for residential use. The San Joaquin County On-Site Wastewater Disposal Standards are based on the 1963 Manual of Septic Tank Practice. ►� The tent from Crites and Tchobanoglous (1998) (Table 4-2) indicates that the typical residential use rate is 70 gallons per day. The EPA(1980) Design Manual (Table 4-6) indicates the typical use rate is 45 gallons per day for a resident. We estimate customer use is 5 gallons per day per visit. On the averag'Fomct ped day use the restroom. `___/ Since the Crites and Tchobanoglous(1998) information is the most current available, our office believes it provides the best estimate of waste water flow for the residential category. The following tables presents the septic waste water uses associated with the Site. The rates 4