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convey a minimum peak flow from the 10 year/24 hour storm event <br /> and with a minimum freeboard design of 0. 3 ' feet . The ditches <br /> have been installed as approved by the Board on the inside of all <br /> cuts and fills so that the flow velocities will not cause adverse <br /> erosion. The ditches are also located away from the toe of the <br /> fills to prevent undercutting during periods of high flow. Where <br /> necessary, rip rap and/or vegetative control measures are also <br /> employed . <br /> The one permanent diversion ditch in Coal Basin is <br /> the Dutch Creek Diversion ditch. This ditch was designed and <br /> constructed to convey the peak flow runoff event from the 100 <br /> year/24 hour storm. It has been designed and constructed using <br /> the best technology currently available to minimize the contribu- <br /> tion of sediment to the receiving stream. <br /> Road ditches have been designed to convey minimum <br /> runoff from the 10 year/24 hour storm event, and have been <br /> located on the inside cuts and through cuts as required by state <br /> and federal regulations . The diversions have been located to <br /> drain the haul roads through properly designed culverts . <br /> All culverts, with the exception of Dutch Creek, <br /> have been designed and constructed to convey at least the runoff <br /> from a peak storm of the 10 year/24 hour storm event . The Dutch <br /> Creek culvert was designed to convey the peak flow from a 100 <br /> year/24 hour storm. Many of the culverts have been located to <br /> convey excess water from the haul and access roads . They have a <br /> minimum diameter of 18 inches . Where necessary, Mid-Continent <br /> has placed energy dissipators such as rip rap and detention <br />