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Road ditches have been incorporated where necessary to convey the runoff <br />• from the LO-year, 24-hour storm. Representative "worst-case" ditch grades were <br />used to calculate the maximum volume of water that must be conveyed to control <br />water from the design storm. The ditch locations are illustrated on Map 8 for <br />milestone sections. <br />1,000 to 2,500 feet <br />4,975 to 6,450 feet <br />8,200 to 8,700 feet <br />. 13,800 to 14,200 feet <br />Data for ditch design are presented on Table 2.05.3-6 and assumes a <br />triangular configuration with sideslopes of 2:1. All of Sun Coal Company's <br />existing ditches exceed the recommended ditch dimensions. In areas where flow <br />velocities exceed 4.0 feet per second, Sun Coal Company minimized erosion poten- <br />tial by lining the ditches with riprap. <br />C <br /> <br />- 183 - (Rev. 5/86) <br />