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August 31, 2004 <br /> NOA Project Number: E04060A <br /> 3.6 Expected On-Site Maximum Septic Tank Usage <br /> The residence on the Site has three bedrooms, which have the potential to be occupied by an <br /> estimated four people. A second dwelling unit may be placed on the Site at some point. A <br /> second dwelling unit is estimated to be two bedrooms in size and has the potential to be <br /> occupied by an estimated three people. Therefore, a total of seven residents will be used to <br /> calculate the residential septic tank usage. <br /> Because Mr. Alegre is unsure of the future commercial uses of the Site, and no information <br /> was available from the San Joaquin County Community Development Department regarding <br /> project applications, two possible scenarios are explored below. The scenarios use the <br /> maximum average daily flow of 6,600 gallons per day (gpd) calculated in the nitrate loading <br /> analysis section below and identify the maximum number of employees that would lead to <br /> this flow. <br /> The estimated sewage flow rates for use categories are available from a number of references. <br /> The uses presented below were guided by the San Joaquin County Sewage Standards (2003), <br /> Crites and Tchobanoglous (1998), and EPA (1980). The San Joaquin County Sewage <br /> Standards does not provide a flow rate for residential use. The San Joaquin County Sewage <br /> Standards are based on the 1963 Manual of Septic Tank Practice. <br /> The text from Crites and Tchobanoglous (1998) (Table 4-2) indicates that the typical <br /> residential use rate is 70 gpd, and the typical office worker (includes commercial and industrial <br /> workers) use rate is 13 gpd. <br /> The EPA (1980) Design Manual (Table 4-6) indicates the typical use rate is 45 gpd for a <br /> resident and 14.5 gpd for an office worker. <br /> Since the Crites and Tchobanoglous (1998) information is the most current available, our <br /> office believes it provides the best estimate of waste water flow for both the residential and <br /> office worker categories. Therefore, 70 gpd will be used for each occupant of the residence, <br /> and 13 gpd will be used for each office worker or mechanic. <br /> Mr. Alegre has indicated that he may use the Site as a truck yard. To identify the impact to <br /> the waste water flow from this use, each visit to the Site by a truck driver is estimated to <br /> generate 5 gallons of waste water. <br /> 5 <br />