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Rule 2.~ Permits • 24-hour storm event by culvert and greater flows (10-year, 24-hour or 20-year, 24-hour precipitation event) as appropriate. LCC will not travel through these crossings when water is flowing. Cross-culvert and gap exit channels will be riprapped down fill embankments and discharge into riprap or straw bales to dissipate energy. Plastic sleeves (elephant trunks) or conveyor belt flumes are a design option to riprap for cross-culvert exit channels. Discharges of runoff from haul roads within disturbed areas will be directed into sedimentation ponds. The watershed networking and configuration necessary for runoff analyses was developed from maps with a 1" = 1000' scale and 10-foot contour intervals. Watersheds were defined by natural drainage basins above the road. Subwatersheds were defined by dendritic drainage patterns within a watershed, as well as soil types and major breaks in terrain. Flows passed by road ditch cross drains are included in upland watershed runoff quantities. Cross-culvert and ditch flows analyses were developed from maps at a scale of 1" = 400' with 10-foot contour intervals. SEDCAD+ Version 3 (Sediment, Erosion, Discharge by Computer Aided Design, developed by Ms. Pamela J. Schwab, Civil Software Design and Dr. Richard C. Warner, Agricultural Engineering Department, University of Kentucky) was used to size drainage structures. SEDCAD+ input parameters and summaries of ditch and culvert designs are presented in Exhibit 14. Maps 2.05.3-2 and 2.05.3-3a show drainage structures associated with the roads. • The culverts listed in Exhibit 14 represent the minimum size culvert required to pass the design flow, except for requirements for culverts over 120 inches in diameter. Multiple culverts were used in those cases where a single culvert exceeded 120 inches in diameter. As previously mentioned, each crossing needs to be field sited and designs modified if required to site specific conditions (width and depth of channel, etc). Alternative designs are multiple culverts or a combination of a culvert(s) and encasing concrete ford to pass the required flow (see Figure 2.05.3-12). Design discharges are included in Exhibit 14 to assist in development of alternative designs for site specific conditions. Drainage structures will be located on ephemeral or intermittent streams. An alternative design for drainage structures is [o pass the 2-year, 24-hour precipitation event by culvert, and the 10- year, 24-hour precipitation event by a combination of the culvert encased in a concrete Arizona crossing. Figure 2.05.3-13 is a sketch of this option. Most haul roads utilize existing gas field roads. Existing and planned culvert sizes and locations are shown on Map 2.05.3-3a. • p,~-~i 2.05-23 (Revised 09/18/01)