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AECOM 5. Leach Field Sizing Leach field pipe length is sized per OWTS Standard section 9.7.2 for non-standard OWTS design. Leach Line Length = (BCT + ADF) x Soil Factor Soil factors are defied per Table 9.7.2, which is referenced as Table 2 below. Table 3. Soil Factor Values per OWTS Standard 9.7.2 Soil Soil Factor Clay and/or Peat 0.25 Silt and/or Sandy Clay Loam 0.225 Sand and/or Sandy Loam 0.2 BSK prepared a Limited Geotechnical Investigation Report (E21-002-01 B) dated February 26, 2021 that states that the soil type is sandy clay loam. Using that information, the leach line length is calculated as: Required Leach Line Length = (1,200 + 4,200) x 0.225 = 1,215 feet Per Section 9.4.1 the maximum length of individual leach lines is 100 feet. Per Section 9.4.5 leach lines must have a clear spacing of 10 feet. Because of this it is proposed that 8 leach lines will be used where 5 lines are 100 feet long and 3 lines are 88 feet long. Seven 60 -inch diameter seepage pits are proposed at the end of seven of the leach lines. Per Section 9.9.8 each 60 -inch diameter pit is equivalent to 84 feet of leach line. Per Section 9.9.10 seepage pits cannot be closer than 10 feet edge to edge. Thus, the total leach lines are proposed to be: 5 lines x 100 feet per line = 500 feet 3 lines x 88 feet per line = 264 feet 7 60 -inch diameter seepage pits x 84 feet per pit = 588 feet Total Provided Leach Line Length 1,352 feet 6. Sewer Pumps Per the OWTS Standard section 9.4, the maximum depth of leach lines is 42 -inches. The longest distance between the commercial buildings and the septic tank is 266 feet. The minimum slope for sewer laterals is 2% per the California Plumbing Code 718.1. Assuming that the lateral invert at the building is 24 -inches below top of grade and that the lot is generally flat, the invert at the septic tank would be 7.3 feet. Because this depth exceeds the 42 -inch limit, a sewer lift station is required. Table 4 provides a summary of fixture unit calculations. Data is taken from the California Plumbing Code Table A 103.1 for Water Supply Fixture Units.