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By Kevin Flynn
Inside-Lane.com

The Colorado Department of Transportation says the current plan once unstable boulders are removed from above the Interstate 70 viaduct through Glenwood Canyon is to repair a large hole in the eastbound structure, then reopen it to one lane in each direction.

That would allow traffic to resume while repairs are made on the larger hole in the westbound structure. The damage is west of the Hanging Lake Tunnels

But there is not yet a time estimate for when the first repairs can be made.

CDOT photo shows mostof the debris cleared from the bridge deck, with two gaping holes in the westbound lanes and median area. The eastbound lanes, nearest to the camera, will be repaired first to allow two-lane traffic to resume.

This morning, CDOT is using a helicopter to drop off drilling equipment and a generator for planned drilling and blasting operations on an unstable 20-foot-diameter boulder high above the highway. If all goes well, crews anticipate bringing the boulder down in the early afternoon. Afterward, the cliff will be scaled of other loose rock and any additional damage this causes to the highway will assessed, CDOT said. That will determine how long it might be until some lanes are reopened.

Crews tried to do this on Tuesday but ran out of daylight up on the cliffs

“A team of six hiked up 900 feet on the mountainside (on Tuesday) and conducted rock scaling operations (removing loose rock material with pry bars and other equipment) until approximately 5:30 p.m.” CDOT said in a statement. “They were able to safely access the unstable rock needing to be brought down. Losing daylight, crews attempted to pry sections loose and locate areas in which to effectively place and then charge explosives, but were unable to do so.

“Tomorrow, March 10th, crews will hike up to the location once again and drilling and other equipment will be airlifted by helicopter to the site. Drilling and blasting as well as other mitigation efforts will be used to bring down the rock. Due the challenging nature of the project, it is difficult to estimate when the mitigation work will be complete and when I-70 may reopen. Should the rock be brought down successfully, causing minimum damage to the highway, crews could then begin repairs to the eastbound lanes in preparation of opening one lane in each direction using the eastbound lanes. Please note that the process to reopen the Interstate is dependent upon the completion of the mitigation work.”

CDOT photo shows the area of the cliffs on the north canyon wall from which the rockslide came.

In the meantime, with I-70 closed between Dotsero and Glenwood Springs, a detour of up to 150 miles remains in place for cross-state traffic.

A huge rockslide early Monday morning in Glenwood Canyon closed Interstate 70 in both directions. Officials are uncertain when it can be reopened.

After hiking two miles up the canyon wall on Monday to inspect the area where the slide originated, CDOT geologists determined that the remaining rock above the highway was too unstable to leave on place.

CDOT maintenance crews worked to break up the boulders and haul them away on Monday.

CDOT photo shows boulders strewn across I-70's eastbound lanes in Glenwood Canyon Monday morning. The slide has closed the cross-state highway.

The slide punctured about a half dozen holes and divots in the two bridges on the west side of the Hanging Lake Tunnels. They carry I-70 over the Colorado River and Union Pacific Railroad, just west of the Shoshone Dam and the ramps that lead in and out of the Hanging Lake trail parking area. The debris was scattered over about a 300-foot length of highway.

Gov. Bill Ritter declared the situation a disaster on Monday, allowing the state to go after assistance from the Federal Highway Administration to help pay for repairs.

I-70 in Glenwood Canyon has average daily traffic of 19,800 vehicles a day, according to CDOT traffic counts. This slide could result in more complicated traffic issues than a similar slide at the same location on Thanksgiving Day 2004. In that case, all of the significant damage was in the westbound lanes, and CDOT was able to restore two-way traffic in about 31 hours by shifting vehicles to one lane in each direction using the eastbound structure. Full repairs took two months.

Scroll around this Google Street View interactive view outside the west portals of Hanging Lake Tunnels to see the cliffs from which the rocks fell.

View Larger Map

But in this incident, both westbound and eastbound structures suffered significant damage. CDOT has to assess the situation more fully before deciding on a course of action. It will use its emergency contracting procedures to meet with contractors over the next couple of days as crews develop repair plans.

In the meantime, CDOT maintenance crews have continued to break up and clear away the boulders that already had fallen.

Some of the boulders were the size of semi-tractors and are being broken up with explosives before they can be moved out of the road. One hole in the westbound lanes was estimated to be 10 by 20 feet, said CDOT spokeswoman Mindy Crane. In the eastbound lanes, there was a six-by-six-foot hole. There is limited mobile phone service deep in the canyon.

Damage to bridge deck on I-70 in Glenwood Canyon can be seen next to one of the huge boulders that smashed down onto the highway early Monday morning. The boulder's size already has been cut down, as the photo shows. CDOT photo.

There might have been a foreshadowing of the slide earlier in the weekend. Motorist Chuck Hickey was headed toward the canyon westbound on Saturday morning when he heard a radio traffic report that I-70 westbound was closed at mile marker 125, the exact location of today’s slide, due to rocks. Because Vail Pass was closed by an accident, Hickey detoured at Copper Mountain to Leadville on CO 91, then took U.S. 24 over Tennessee Pass to I-70 at Minturn.

“I had KOA on and they reported it,” Hickey reported on Facebook. “Said it was westbound I-70 closed at MM 125. But when I got back onto I-70 at Minturn, they no longer were reporting it and when I went through there, there were no trucks or anything. But people in Leadville were talking about it when I stopped.”

Crane said the rockslide chute is close to the one that closed the highway five years ago. About 20 boulders are on both sides of the highway, the largest being estimated at 66 tons. They range from three feet to 10 feet in thickness. The rocks also damaged guardrail and concrete barrier along the highway.

The Thanksgiving Day 2004 slide closed the road for a full day and forced a detour of one lane in each direction for two months while repairs were done. That slide punched several holes in the bridge deck including one that was 30 by 15 feet.

Bridges carry I-70's eastbound and westbound lanes out of the west portals of the twin bores. This is where the slide occurred. Photo by Matt Salek, Highways of Colorado.

Those repairs were done by Kiewit Construction under a $681,775 contract that included a bonus for finishing early. CDOT spent a total of $1.2 million on the incident, including clean-up and rock-scaling in the chute to clear out other loose rock.

The new slide occurred around midnight and no one was injured. CDOT has an operations center inside the tunnel that is staffed around the clock to manage traffic. Read an article about the center here.

Detours are daunting to long-distance traffic.

Drivers headed west can exit I-70 at U.S. 40 at Empire, head over Berthoud and Rabbit Ears passes to Steamboat Springs, then back to I-70 at Rifle via Craig and Meeker – a distance of 290 miles, or 150 miles farther than the distance from Empire to Rifle on I-70.

Other detours over CO 9 at Silverthorne or CO 131 at Wolcott add 115 miles and 142 miles, respectively, to the trip.

CDOT Photo shows the damage to the I-70 bridge deck caused by this morning's rockslide in Glenwood Canyon

CDOT crews are assessing the damage before deciding how to proceed.

“We have no estimate as to how long the highway will remain closed at this time,” CDOT spokeswoman Stacey Stegman said. Crews were searching for the source of the rockslide first to determine whether it was safe to be in the area without more rocks coming down.

I-70 through Glenwood Canyon is an internationally acclaimed stretch of roadway that won award for its context-sensitive design and construction. Because of the high unstable cliffs, there are areas prone to rockslides. Read this comprehensive photo-filled feature about the history of I-70 in Glenwood Canyon at Matt Salek’s Highways of Colorado site.