A Dec. 15 rock and mud slide damaged a portion of a North Carolina roadway known for its scenic vistas.
Debris toppled onto the Blue Ridge Parkway at milepost 401, which is mid-way between the French Broad River and Mt. Pisgah in Buncombe County, NC. According to Jeff Bradley, project manager of Taylor & Murphy Construction Co. Inc., in Asheville, NC, repair work began in early February.
Taylor & Murphy is the general contractor that will handle all of the repair work with the exception of the paving, which will be subcontracted to APAC-Atlantic’s Asheville division. Estimated cost for repairs is $460,000.
“Repairs are moving along smoothly, however an estimated 10,000 cubic yards of mud and rock will need to be removed and hauled away from the slope and road before repairs to the parkway can begin,” Bradley stated.
“When the slide occurred,” Bradley said, “it sloughed off rock and mud into the road, leaving behind loose rocks and mud on the slope. The first step in repairing the job site was to build a road to the top of the slope where the slide started. Then, using a Caterpillar 330 excavator with a hydraulic hammer, we bust the rock down to expose the cut rock.
“Once we get the slope back to solid smooth rock we will have about 300 to 400 feet of road to repair and resurface with asphalt [approximately 100 tons], along with paving some concrete ditches next to the slope, repairing shoulders and seeding.”
According to Phil Noblitt, spokesman of the Blue Ridge Parkway, the mudslide caused limited impact to traffic along this section of the parkway.
“The parkway is often closed during winter because of snow and ice,” Noblitt stated. “This year, however, was unusually mild and this section would have been open at least part of this period if it were not for the slide.”
Equipment used at the job site was all owned by Taylor & Murphy and includes a Caterpillar 320 excavator used to load the trucks, a Caterpillar 330 excavator with a hydraulic hammer to bust the rock down, a Caterpillar D6 bulldozer and a Caterpillar 924 loader.
“According to the contract, the project is to be completed by June,” Bradley said. “However, the project is moving along quite well and we anticipated a much earlier completion date.”
According to the National Park Service the number of visitors to the Blue Ridge Parkway dropped in 2004 for the second consecutive year — which is the first two-year decrease on the scenic drive since World War II.
This decrease is somewhat attributed to damage to the parkway from heavy storms in Virginia and North Carolina and hurricanes Frances, Ivan and Jeanne. Approximately 19.5 million people visited the parkway last year, which is down almost 4 percent.
According to Noblitt, mud and rockslides along the parkway are an ongoing problem due to the high elevation of cut slopes on which it was built.
“The Blue Ridge Parkway is one of the most vulnerable highways to slides due to the nature of the way it was built,” Noblitt explained. “The parkway runs lengthways along the spine of a number of mountain ranges and was built primarily to showcase the scenery in the region not as strictly a transportation route.”
According to Noblitt, the parkway staff identifies the deficiencies in the parkway, resurfacing needs and tunnel rehabilitation and then obtains funding. The parkway then coordinates with the Federal Highway Administration, which provides inspection, engineering and contract administration services.
“Cost of slide clean up and repair varies greatly according to the complexity of the job and the amount of fallen and unstable material that has to be removed,” Noblitt said. “A relatively small slide that falls from a cut slope might cost less than $100,000. A major slide that requires removal of large amounts of adjacent unstable material can cost $1 million. Slides that involve fill slopes are more costly to repair. In these cases, the roadbed and supporting structures have to be rebuilt.”
The total price tag to clean up slides this year will reach into the millions of dollars.
“We now estimate the multiple slippages [or slides that involve fill slope] between Mt. Mitchell and NC 80 [mileposts 355 to 344] and the slides south of U.S. 221 near Linville Falls [mile 321-322], all of which occurred due to the hurricanes in the fall of 2004, will cost $6 to $8 million to repair,” Noblitt said.
Parkway officials are working with the North Carolina Geological Survey to assess future rockslide potential.
“I am confident we will be able to obtain requested funds for any site that the study identifies as posing an extreme and imminent threat,” Noblitt said. “That said, the parkway crosses five mountain ranges with underlying rock that, geologically, is highly deformed. There is simply no way to eliminate all areas that have instability and show slide potential.” CEG