WSP08712 - Laserfiche WebLink

Home Browse Search

I I I I Vertical shjlfts from the ground surface to the tunnel bore would generally be used for diversion of water from streams into tunnels, Shafts would probably be drilled upward from the tunnel and the shaft muck disposed with tunnel muck. 2. Disposal of Tunnel Muck Tunnel excavation would produce large quantities of excavated rock and earth, commonly referred to as "tunnel muck", which would require disposal. With the exception of the Red Cliff and Turkey Creek Tunnels under Plans F and F-1, and the tunnels under Plan G, all tunnels would apparently be bored through igneous and/or metamorphic rock which is only superficially weathered. Muck produced from these types of rock would probably range in size from blocks one-half cubic yard in volume to rock dust. It is expected that the amount of minus 200 mesh size material resulting from blast - excavation will be no more than 2 to 3 per cent by weight.' I I I I Considerably more fines will occur when faults or shear zones are crossed by the tunnel. Generally, it is expected that blast- excavated tunnel muck from igneous and metamorphic forma- tions would be reasonably clean and inoffensive and would create only minor amounts of dust and potential water-borne turbidity, Muck produced by tunnel boring machines would contain much more fine material. Muck produced from tunnels in sedimentary rock would also be expected to contain considerable fines regard- less of tunneling method. I I I I The tunnel muck wou ld likely be unsu itable for use in construc- tion of project components, except as a surfacing and embank- ment material. Select muck would be used for surfacing work areas, access roads and parking areas to inhibit dust and erosion, to L") ~ o "Predicting Materials Handling Properties of Tunnel Muck", by H. F. Haller and H. C. Pattison, Proceedings North American Rapid Excava- tion and Tunneling Conference, 1972, Vol. 2, p 1279, I I Under Plans E, F, F-1, and F-2, excess tunnel muck would be placed in dam embankments. Under Plans A, B, C,and D, excess muck would be deposited in an approved disposal area, com- pacted and shaped to designed contours, and then covered with a minimum 12 inches of job excavated material. The surfaced area would then be ferti Iized and seeded with native grasses and planted with seedling trees. An alternative method of disposal of excess muck would be placement in off-site embankment or surfacing projects if such projects are in progress in the vicinity of the Project Area during the construction period. Disposal of muck from the Turkey Creek Tunnel under Plans F and F-1 and from the tunnels under Plan G should be covered under the E IS being prepared for the Eagle-Colorado Project by the DWB. C. ROAD CONSTRUCTION Roads would be constructed for access to working tunnel portals, dam sites, and pipeline rights-of-way. Access to construction areas in the Homestake and Cross Creek Valleys would be as described under Section It I.A-1. Access for the Turkey Creek Tunnel construction under Plans F and F-1 and for all construction under Plan G will be covered under the EIS prepared by the DWB. Access roads would be constructed to planned grades and would be graded and drained to inhibit erosion, The roads would be surfaced with select tunnel muck or other granular material to inhibit dust and surface erosion. After completion of construction, all roads except those classed as permanent by the U. S. Forest Service would be restored to satisfactory grades as covered under Section III.A-5. The re- stored surface would be covered with site excavated soil, fertil- ized, and seeded to native grasses, Seedlings, trees, and shrubs 25