2012-07-10_GENERAL DOCUMENTS - C1981041

Home Browse Search

not utilized to provide the necessary flow capacity along the segment between the dip section concrete structure at the upper end and the two 81" by 59" culverts at the lower. Additionally, the Pond 6 embankment was built up and fortified with riprap. The rock from the check dams was used for the construction of rock groups placed on the reclaimed surface of CRDA -1 & 2 and other reclamation uses. Since material generated from the Coal Canyon Realignment was utilized for the reclamation of CRDA -2, the realignment was performed concurrently with the 2002 refuse pile reclamation project. During 2003, work was performed in Coal Canyon below the outlets of the large double culverts. Scour protection was provided at the outlet of the culverts. Pursuant to TR-42 approved in 2003, the Division approved the installation of a riprap transition zone at a "nick- point" in a lower segment of the Coal Creek channel, in the vicinity of the former Haul Road 2 channel crossing. Approximately 700 -feet downstream of the double culverts, a transition zone was installed. See Exhibit 8B and Appendix 13 -2, pages Misc -13 through Misc -22 of the permit document for details of the scour protection and transition zone. Scour protection was installed at the outlet of the upper dip section during 2002. Sections of the Coal Canyon permanent channel diversion near Ponds 6 and 10, and the Coal Gulch drainage in the vicinity of Pond 11 were originally planned and approved by the Division to be re- aligned and modified in conjunction with removal of the ponds. The Coal Gulch and sections of Coal Canyon drainage were going to be diverted back through the pond locations which would approximate these drainages original configuration. However, during a meeting between SCC and the U S Corp of Engineers it was recommended that Coal Canyon drainage, which was previously approved for realignment during the reclamation of Ponds 6 and 10, remain in its current configuration. The re- routing of the Coal Canyon and Coal Gulch drainages would require a permit from the U S Corp of Engineers. Carrie Sheate of the US Corp of Engineers proposed that realignment of Coal Canyon for the sake of routing the drainage back to its original contours would not be a justifiable reason for issuing a Corp Permit. The Division concurs with not re- disturbing the current alignment of Coal Canyon and Coal Gulch and is proposing to approve PR -5 leaving these drainages in their present alignment and configuration. Coal Canyon drainage and Coal Gulch are stable in their current position. To date there have been no other comments or objections by any other local, state or federal agencies notified of this proposal. Upon approval of PR -5 Ponds 6 and 10 will be backfilled and graded, as depicted in Exhibit 9C, so as not to disturb the current alignment of Coal Canyon. The reclamation plan of Pond 6 (PR- 5) will also include more fill along the toe of CRDA #1, providing additional protection from any possible cutting into the refuse pile. See Appendix 13 -2, pages Misc 13 through Misc 19 of the permit document for details of the current Coal Canyon Runoff and Drainage design. The design information shows that the diversion drains a watershed greater than one square mile and has been appropriately designed to pass safely the peak runoff of a 100 -year 24 -hour event. A second permanent channel diversion has been approved for the lower segment of Coal Gulch in the vicinity of Sediment Pond 11. The pond 11 embankment is located immediately northwest of Coal Gulch. A small portion of this embankment will be removed so pond 11 is opened to Coal Gulch. The embankment material and another 3,500 cubic yards from topsoil stockpile number 1 will be placed in Pond 11. This material will be used to create a positive 0.5% grade so the reclaimed pond 11 area drains to Coal Gulch. Three to five feet of fill will be Permit Revision No. 5 23 July 10, 2012