Laserfiche WebLink
Other applicable methods of culvert design include the use of charts developed by the Federal <br />Highway Administration, published in Hydrologic Engineering Circular HEC -5 (FHA, 1980), <br />and Hydrologic Design Series HDS-3 (FHA, 1980). <br />Charts published in HEC -10 (FHA, 1978) are also used; however, exit velocities must then be <br />determined by other methods. Headwater conditions are typically examined by using HEC -5 <br />inlet control nomograph. To be conservative and to allow for adequate freeboard, New Horizon <br />usually uses "projecting" conditions. <br />As virtually all culverts have free outfalls, inlet control assumptions can be verified by the "Pipe <br />Flow Charts" in HDS-3. If flow in the culvert has a free surface, entrance control exists and exit <br />velocity can be approximated by using the greater of normal or critical velocity determined by <br />the "Pipe Flow Charts" in HDS-3. <br />6. Maintenance <br />Haul roads will be inspected on a daily work basis at the New Horizon Mine. If, upon inspection, <br />it is determined that repairs are needed, appropriate repairs such as, but not limited to, grading, <br />filling of potholes, replacement of the road surfaces, revegetation of side slopes and watering for <br />dust control, will be conducted as necessary. Magnesium Chloride solution may be utilized to <br />control fugitive dust. The solution will have an approximate concentration of 30% and will be <br />applied at a rate of one-half gallon per square yard of surface area. The solution of Magnesium <br />Chloride will be applied by a commercial company specializing in this product and will be <br />dispensed from a truck with approximate 16 foot spray bars. One-two applications are <br />anticipated per year. <br />7. Restoration <br />Unless New Horizon requests retention of haul roads for post mining land use and the DRMS <br />approves such request, immediately after the road is no longer needed for operations, <br />reclamation, or monitoring: <br />a. The road will be closed to vehicular traffic; <br />b. The natural -drainage patterns will be restored; <br />c. All culverts will be removed; <br />d. Roadbeds will be ripped, plowed and scarified; <br />Section 2.05.3(3) Page 22 April 2017 (MR -104) <br />