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AECOM <br />4. Septic Tank Sizing <br />We understand the residential care facility consists of three buildings with the following <br />characteristics shown in Table 1. <br />Table 1. Residential Care Facility Characteristics <br />The San Joaquin County OWTS Standards, dated 2017, Table 6.6, provide the per capita water <br />uses for commercial OWTS. Table 2 provides the average daily flow (ADF) calculation. <br />Table 2. Average Daily Flow (ADF) Calculation <br />Persons <br />Fixture Units <br />Water Use <br />Residents <br />Employees <br />Kitchen <br />Sink, <br />domestic <br />Lavatory <br />Water Closet, <br />1.6 GPF <br />Flushometer <br />Tank <br />Clotheswasher, <br />domestic <br />Building 1 <br />13 <br />3 <br />1 <br />3 <br />3 <br />2 <br />Building 2 <br />4 <br />0 <br />1 <br />3 <br />2 <br />1 <br />Building 3 <br />6 <br />2 <br />1 <br />3 <br />3 <br />1 <br />Total <br />23 <br />5 <br />3 <br />9 <br />8 <br />4 <br />The San Joaquin County OWTS Standards, dated 2017, Table 6.6, provide the per capita water <br />uses for commercial OWTS. Table 2 provides the average daily flow (ADF) calculation. <br />Table 2. Average Daily Flow (ADF) Calculation <br />Total 4,100 <br />The septic tank volume is sized per OWTS Standard section 4.1.12 where basic tank capacity <br />(BTC) is equal to 1,200 gallons. <br />Where ADF < 1,500 gallons per day, <br />Volume = BTC + ADF <br />Where ADF > 1,500 gallons per day, <br />Volume = 1,125 + 0.75 x ADF <br />Because the average daily flow is greater than 1,500 gallons per day, the second equation is used. <br />Volume = 1,125 + 0.75 x 4,100 = 4,200 gallons <br />Water Use <br />Subtotal <br />Type <br />Quantity <br />Reference <br />(gpd) <br />(gpd) <br />Use "P" Institutions Other <br />Residents <br />23 <br />Than Hospitals <br />175 <br />4,025 <br />Use "R" Industrial Building <br />Employees <br />5 <br />No Food Cafeteria <br />15 <br />75 <br />Total 4,100 <br />The septic tank volume is sized per OWTS Standard section 4.1.12 where basic tank capacity <br />(BTC) is equal to 1,200 gallons. <br />Where ADF < 1,500 gallons per day, <br />Volume = BTC + ADF <br />Where ADF > 1,500 gallons per day, <br />Volume = 1,125 + 0.75 x ADF <br />Because the average daily flow is greater than 1,500 gallons per day, the second equation is used. <br />Volume = 1,125 + 0.75 x 4,100 = 4,200 gallons <br />