Glenwood Canyon rock slide – progression |

Glenwood Canyon rock slide – progression

AP photo Crews work to clear a section of Interstate 70, Friday, Nov. 26, 2004, through scenic Glenwood Canyon in Glenwood Springs, Colo., after a rock slide Thursday sent boulders crashing onto the road, closing it for more than a day. (AP Photo/Rocky Mountain News, Evan Semon)

By Dennis WebbPost Independent StaffExperts are discounting the possibility of any connection between recent seismic activity in western Colorado and Thanksgiving Days rockfall in Glenwood Canyon.A magnitude 2.5 earthquake struck Friday afternoon 15 miles southeast of Glenwood Springs, a day after the rockfall that knocked holes in Interstate 70 and closed it for some 30 hours. While earthquakes sometimes are preceded by slight tremors, the U.S. Geological Service National Earthquake Information Center reports no Garfield County quakes in the days prior to the rockfall. And a scientist there says it would have taken a larger quake than Fridays to shake loose rocks of the size that came down Thanksgiving Day. There is no way there is any connection, said Waverly Person, a geophysicist at the center.Another minor quake occurred in the Paonia/Crawford area on Nov. 23, two days before the rockfall, but that was way too small and too far away to have been a cause, Person said.Even Fridays quake would not have been close enough to affect Glenwood Canyon, Person said.Anything that would have caused the rockfall would have done other damage as well, he said.Residents in Missouri Heights and up Cattle Creek reported feeling Fridays quake, but there were no reports of damage.Ty Ortiz, who manages the Colorado Department of Transportations rockfall program, shares Persons view that it would take a bigger earthquake than Fridays to cause the kind of rockfall that occurred last week.That magnitude of earthquake is pretty small as far as earthquakes go, he said. Had there been a large-magnitude earthquake in the canyon, yeah, certainly, that could stir things up a bit.Colorado has a history of earthquakes, but almost all have been minor ones. In Ortizs opinion, the freeze-thaw cycle creates a far bigger threat of rockfall. That cycle, suspected in Thursdays incident, causes moisture between rocks to expand like a jack, throwing the rocks off-balance.Eventually they just get to the point that they cant support themselves, he said. Its almost unpreventable, something like that.Typical techniques such as bolting rocks to cliff-sides wouldnt have stopped a massive rockfall. Even dozens of rockfall fences probably wouldnt have made a difference, Ortiz said.It was several orders of magnitude above whats typically protected from rockfall fences these days, he said.No one was injured in Thursdays incident, but falling rocks have killed people before in the canyon.Over the years, CDOT has spent probably about $6 million in Glenwood Canyon on fencing, netting and other rockfall mitigation work, Ortiz estimated. The highways alignment was partly dictated by an attempt to minimize the risk posed by overhanging rock.]CDOT rates some 750 sites statewide for rockfall danger, but views Glenwood Canyon as a special condition with its own rockfall rating. The agency evaluates the danger there on a continuous basis. But some rockfalls cant be predicted or prevented, Ortiz said.Geologically speaking these things occur from time to time, he said. If the mountains going to hiccup, the mountains going to hiccup. … Theres really not much you can do about it.Contact Dennis Webb: (970) 945-8515, ext. 516dwebb@postindependent.comVail Colorado

By Greg MassPost Independent StaffA massive rockslide punched van-size holes in the decking of Interstate 70, closing the highway in both directions all day on Thanksgiving and sending holiday travelers on a 220-mile detour to get through the mountains. There were no injuries, but Colorado Department of Transportation officials said they were hoping to open one lane in each direction by late Thursday night and said final repairs to the highway could take weeks or even months. CDOT suggested that drivers use U.S. Highway 40 and State Highway 13 to get around the canyon (see alternate routes above). Some motorists tried to take Cottonwood Pass between Missouri Heights and Gypsum, but CDOT officials said there was too much snow on the high dirt road, prompting them to close the back route. On Thanksgiving Day at noon, CDOT deputy maintenance superintendent Del French said he anticipated that once the highway reopens it will only be able to accommodate one lane of traffic in each direction. We anticipate bottlenecking, he said. What weve got here is obviously a substantial rockslide that caused substantial damage. It could be a couple of months before its fixed. The slide zone was estimated to be up to 100 feet long and eight to 10 feet deep. Between 30 and 40 boulders came down the canyons steep north wall.Many CDOT employees were unexpectedly called into work on the holiday, trading family, turkey and football for backbreaking labor while trying and get the main thoroughfare through Colorados mountains back open for traffic.No doubt, a lot of holiday travelers also were caught off guard as they tried to make their way through the canyon to celebrate Thanksgiving with loved ones. According to a CDOT news release, two bridges have holes in their decks on eastbound I-70. On the westbound lanes there is also significant damage. CDOT estimates that about six boulders were embedded up to eight feet into the roadway. Also, two retaining wall panels along the westbound lanes were completely knocked out.The slide happened about 7:30 a.m., just yards east of the Hanging Lake exit offramp at mile marker 125 and about a half mile east of the Hanging lake Tunnels. French guessed that the rocks fell from about three-quarters up the canyon wall, hundreds of feet above the highway. Were trying to evaluate when we can open the road up. As you can see, were a long way away from it, French said. CDOT bridge engineer Mark Leonard was on the scene checking the structural stability of the bridge that supports the eastbound lanes and the T-wall that supports the westbound lanes. Hes checking to see if we will be able to open the bridge and if there is lateral stress, French said. Rocks are laying against the girders.CDOT spokeswoman Stacey Stegman said Leonard found no significant structural damage to the highways substructure. The two rocks that caused the most damage, each the size of a van, ended up at the bottom of the Colorado River. The rocks punched holes through the road, damaging large sections of guardrail. The westbound lanes had a gaping hole about 25 feet wide and 10 feet long.Cracks in the highway were also visible, stretching up to 20 feet from the edge of the mammoth hole. Whenever you have a crack like this, French said as he pointed to the largest one, we have to excavate out to do a preliminary repair, then well evaluate it.The most damage to the highway was caused by two van-sized boulders when they pounded the I-70 deck, broke the median barrier, then crashed through the guardrail before rumbling into the bed of the Colorado River. Trails of damage could be seen across the river where the rocks apparently flew over the river and hit the other bank before rolling down to the water. Other rocks on the highway were piled 10-12 feet high in some areas. Boulders too large to be scooped up by front-end loaders were blasted apart by CDOT workers. They drill one hole into the rock, put primer down in it, then they have these things like shotgun shells and they stack them, French said. In the background, a worker yelled, Fire in the hole, pulled a string, and in a cloud of dust, the rocks were blasted into several pieces. Weve got to get them to a size where we can use them, he said. The smaller pieces were then picked up by front-end loaders and temporarily stored on the Hanging Lake exit offramp. Were just cramming them down here. The hanging Lake rest area will be closed for a while. We just dont have time to haul them out, he said. When talking about his missing traditional Thanksgiving television staples such as the Macys parade in New York City, French commented. There aint no parade comin through here.Contact Greg Mass: (970) 945-8515, ext. 511 gmasse@postindependent.comVail Colorado

Daily Staff ReportColorado Department of Transportation spokeswoman Stacey Stegman said the department’s engineers had met with three contractors at the site of the slide.”Because of the huge amount of damage, contractors have said that they expect at least six weeks of work before they can get the highway open on all four lanes,” Stegman said.Stegman said CDOT received $1 million in emergency funding from the state Transportation Commission to make the repairs.The rock slide sent more than three dozen boulders – some as big as vans – crashing onto I-70. No one was hurt, though, because a truck crash had closed the road at the time.Vail, Colorado

by Dennis WebbGlenwood Post-Independent Staff WriterGLENWOOD CANYON – Repairs to Interstate 70 in Glenwood Canyon could be completed within two months – weather willing.An estimated 200 tons of rock fell about 1,500 feet onto the highway on just west of the Hanging Lake Tunnels on Thanksgiving Day, knocking van-sized holes through the deck in each direction and closing I-70 for about 30 hours. Since then, traffic has been restricted to one lane in each direction, which will continue to be the case during the construction work. Trucks more than 12 feet wide and 100 feet in length continue to be prohibited from traveling through Glenwood Canyon.The eastbound lanes will be repaired first, and one eastbound lane kept open during that work, which contractors expect to take about a month. Then both westbound and eastbound traffic will be shifted to the eastbound lanes while work takes place on the westbound lanes.The contractor hired to do that work, Kiewit Western, will fix eight damaged sections of bridge deck on the eastbound lanes and roadway damage on the westbound lanes. The work will require a significant amount of pavement to be removed and replaced, according to the Department of Transportation.Hunter Sydnor, a spokesman for the contractor, called 60 days “a very aggressive schedule” for repairing the highway.”We feel very confident we can get the job done in 60 days, but there’s always the weather that’s going to be the unknown in all of this work,” Sydnor said. “But I think we’re prepared to get it done.”Damaged sections of several hundred feet of concrete barrier and guardrail will be replaced. And Kiewit Western will design and build about 50 feet of new retaining wall, about 23 feet high, along the westbound lanes to replace damaged sections.The Department of Transportation has previously estimated that the cost of the rockslide will reach $1 million. Agency spokeswoman Mindy Crane said that’s still possible, when expenses such as the past few days’ cleanup work and possible contract revisions and late penalties are considered.If the contractor does not finish in 60 days, a $5,000-per-day penalty could kick in. Kiewit Western would be rewarded $5,000 for each day it finishes early, up to a maximum reward of $35,000.Crane asked motorists to drive carefully during the repair work. Traffic will be shifted around and work will take place close to traffic, she said.”The lanes might not look the same every day. It’s very important for people to drive slowly and pay attention,” she said. “For everybody’s safety, drive slowly.” Vail Colorado

By Scott CondonAspen Times Staff WriterThe landslide that complicated the lives of so many travelers on Interstate 70 during the holiday weekend was so massive and unusual it even amazed a geologist who helped build the road.Rick Andrew said the landslide was a “really large, very unusual, rare event.” Such occurrences, he said, are referred to as “100-year events” because the probability of their happening is so low.Andrew is a former staff geologist and current consultant with the Colorado Department of Transportation. He helped determine the location of retaining walls and other mitigation measures when the four-lane interstate was built through the canyon in the 1980s.Andrew said there was no way to anticipate Thursday’s slide. It wasn’t a case of rocks becoming dislodged from dirt and rolling down a dirt slope. Instead, quartzite broke off a sheer cliff a half-mile west of the Hanging Lake Tunnel.”If you think about a glacier calving off – that’s what this was like,” he said. The landslide dumped 1,500 to 1,700 cubic yards of rock onto the eastbound and westbound lanes of the interstate, Andrew said. To put that into perspective, the landslide sent debris equivalent to 170 dump truck loads down the cliff face, onto the slope just above the highway and onto the four lanes. No one was injured.CDOT officials estimate the interstate suffered $1 million in damage.The largest boulder Andrew saw was 20 feet by 20 feet. He said material slid from a cliff face about 1,300 feet above the interstate. The chunk that broke off was about as big as a typical ranch-style house, he said.The crashing chunks of rocks sheared off 10 to 15 large-diameter spruce trees, Andrew said.One lane in each direction was opened by about 3:15 p.m. the Friday after Thanksgiving, after CDOT crews hauled material away and blasted additional rocks from a slope above the road. Once the threat of further sliding was reduced and the integrity of land bridges was tested, the interstate was reopened.The plummeting boulders punched holes on the inside and outside of the lanes on the land bridges but spared the middle, Andrew said. That’s why the lanes could be opened so soon, he said.The work was just a Band-Aid for the busy interstate.”We’ll be looking at weeks, if not a month, of work,” said CDOT spokeswoman Stacey Stegman. “We’re looking at probably $1 million in damage.”Andrew said even though this landslide was an unusual event, smaller slides are common and will continue in Glenwood Canyon. They are simply a product of snow or rain loosening rocks or freeze-and-thaw cycles sending material downslope.Vail Colorado

by Tamara MillerVail Daily Staff WriterGLENWOOD CANYON – Karl Mendonca unexpectedly got the day off Friday, thanks to a massive rockslide that kept part of Interstate 70 through Glenwood Canyon closed for nearly two days.Mendonca lives in Edwards and commutes to his job with the Bureau of Land Management in Glenwood Springs. He was scheduled to work, but with the only direct route still closed the Friday after Thanksgiving, he decided to stay home. “I’ll spend the day with my family,” Mendonca said. “We’re probably not going to go shopping, though.”Geologists still haven’t determined the cause of the Thanksgiving rockslide, which was estimated to be up to 100 feet long and 8 to 10 feet deep. Between 30 and 40 boulders came down the canyon’s steep north wall, some breaking through the roadway.Boulders too large to be scooped up by front-end loaders were blasted apart. The highway, one of the nation’s vital thoroughfares, was closed in both directions all day on Thanksgiving. Crews opened one lane in each direction by the next afternoon. Still, it could be weeks until all lanes are re-opened because of the significant amount of damage, Colorado Department of Transportation officials said. Transportation crews and private contractors finished clearing the rocks from the original slide the next day, but were blasting loose rocks from the sides of the mountain, CDOT spokeswoman Stacey Stegman said. The crews hoped to prevent more rock from falling.Snowy weather hindered their efforts and the wet ground could loosen more rock from the canyon’s walls, Stegman said. “This is the worst I’ve seen in my eight years,” Stegman said.No one was hurt in the rockslide because the highway had been closed earlier the morning of the slide when a truck overturned. A rockslide in 1995 claimed three lives in the canyon that begins in extreme western Eagle County and though which the Colorado River runs.Warren Bronson, who lives in Parachute, was heading home from Denver earlier Friday afternoon, he said. While gassing up at an Avon gas station, he was surveying a road atlas to find the best alternate route home.”I have to work tomorrow, so I got to get home today,” he said. Travelers were directed around the interstate Thanksgiving and the day after. Westbound travelers could take Colorado Highway 131 at Wolcott, drive through Steamboat Springs on U.S. Highway 40, then take state Highway 13 to meet up with I-70 at Rifle. Eastbound travelers were instructed to take the same route in reverse. But the 220-mile detour – at least a three-hour drive in clear conditions – was too much for some. Local hotels and motels saw an increase in bookings Thanksgiving night because of the closure.”Just looking at the report, there were a few more rooms (occupied),” said Glenn Lowe, manager of Eagle’s Best Western Hotel.Some motorists tried to take Cottonwood Pass between Missouri Heights and Gypsum, but transportation officials said there was too much snow on the high dirt road, prompting them to close the back route. The Associated Press and the Glenwood Springs Post Independent contributed to this report.Vail, Colorado

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