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Tables 13-5 and 13-6 contain an inventory of existing and proposed culverts at the Seneca II-W Mine. <br />. Figure 13-3 and Figure 13-4 show typical installation of culverts. Other applicable methods include the use <br />of charts developed by the Federal Highway Administration, published in Hydrologic Engineering Circular <br />HEC-5 (FHA, 1980), and Hydrologic Design Series HDS-3 (FHA, 1980). Charts published in HEC-10 (FHA, <br />1978) are also used; however, exit velocities must then be determined by other methods. Headwater <br />conditions are typically examined by using HEC-5 inlet control Homographs. To be conservative and to allow <br />for adequate freeboard, SCC usually uses "projecting" conditions. <br />As virtually all culverts have free outfalls, inlet control assumptions can be verified by the "Pipe Flow Charts" <br />in HDS-3. If flow in the culvert has a free surface, entrance control exists, and exit velocity can be <br />approximated by using the greater of normal or critical velocity determined by the "Pipe Flow Charts" in <br />HDS-3. <br />Maintenance. Access roads will be inspected on a daily work basis at the Seneca !I-W Mine. If, upon <br />inspection, it is determined that repairs are needed, appropriate repairs such as, but not limited to, blading, <br />filling of potholes, replacement of the road surfaces, revegetation of side slopes and watering for dust <br />control, will be conducted as necessary. <br />Restoration. Unless SCC requests retention of access roads for postmining land use and the Division <br />approves such request, immediately after the road is no longer needed for operations, reclamation, or <br />• monitoring: <br />a. The road will be closed to vehicular traffic; <br />b. The natural-drainage patterns will be restored; <br />c. All bridges and culverts will be removed; <br />d. Roadbeds will be ripped, plowed and scarified; <br />e. Fill slopes will be rounded or reduced and shaped to conform the site to adjacent terrain <br />and to meet natural-drainage restoration standards; <br />f. Cut slopes will be shaped to blend with the natural contours; <br />g. Terraces will be constructed as necessary to prevent excessive erosion and to provide <br />long-term stability incut-and-fill slopes; <br />h. The regraded area will be covered with topsoil in accordance with the approved <br />reclamation plan; <br />i. Unless otherwise authorized by the Division, all road-surfacing materials will be removed, <br />hauled or conveyed and disposed under Rule 4.11.4, <br />On behalf of the postmining landowners, SCC intends to leave the following access roads as <br />permanent postmining roads. Copies of the written requests from the landowners are presented in <br />Attachment 20-2. <br />• Oil Well Access Road <br />Ridgeline Access Road <br />PR-05 35 Revised 01/06 <br />