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(unnumbered culverts). This same procedure was used to find the year of <br />highest runoff into the Moffat Area sediment pond. The year of highest runoff <br />for the sediment pond can be found in the Sediment Pond Section 9.6.1. <br />3.5.3.9 Peak Flow Determination for Culverts in East Ridge (E), <br />Center Ridge (C), Skyline (SK) and Tipple Area (TA) <br />The drainage areas of these culverts will not be disturbed by mining or <br />reclamation. Therefore the condition of these drainage areas will remain the <br />same for the life of the culverts. Table 3.5-2 lists the design criteria used <br />to determine the peak flow of the culverts. The drainage areas for all <br />culverts with the exception of the Tipple Area culverts can be found in <br />Exhibit 3.5-22. The Tipple drainage areas can be found in Exhibit 4.6-21. <br />Appendix 3.5-A lists the results of the computer simulations for the drainage <br />areas of the culverts. <br />Drainage areas for Tipple Area culverts TA-11 through TA-18 are not <br />listed Table 3.5-2 nor were computer simulations performed on these culverts. <br />All of these culverts were existing at the time of the original permit <br />submittal and only provide drainage in and about the loadout facility. The <br />purpose of these culverts is to prevent "standing water" from occurring at the <br />loadout facility in low lying areas. It was not considered necessary to <br />perform computer simulations on these culverts because none of the culverts <br />service a drainage area greater than 2.5 acres and previous computer <br />simulations on drainages of similar or larger size (i.e., TA-1 and TA-8) did <br />not provide peak flows sufficient to suggest that the existing culverts may <br />not be adequate. <br />3.5.3.5 Culvert Design <br />Using the computer generated peak flow rates, the culverts were sized <br />from Figure 4-18 of the publication "Handbook of Steel Drainage and Highway <br />Construction Products", 1977. They were sized for zero head and inlet <br />control. Table 3.5-3 lists the peak flow rates, size required for each <br />culvert, the culvert size existing or to be used, and the appendices where the <br />peak flow rates were determined. It should be noted that no runoff was <br />3.5-Sb May 14,1993 <br />