GLENWOOD SPRINGS, Colorado — Mitigation work is expected to begin today on the area above Interstate 70 in Glenwood Canyon where a rock fall around midnight Sunday night closed a section of the interstate.

More than 150 tons of rocks, debris and massive boulders broke lose from the canyon walls, smashing onto the highway, damaging the roadway near the Hanging Lake exit.

Colorado Department of Transportation (CDOT) geologists assessed the fall area Monday, checking for unstable rocks and to determine the potential for additional slides, according to program engineer Joe Elsen. CDOT reported that no lanes of I-70 would reopen until rock fall mitigation is complete.

“There is still more rock up there that is most likely going to be scaled,” Elsen said.

CDOT Geologists assessed one particular rock above the highway and determined that it is too unstable to remain in place. Early today, rock scaling crews will be meeting to determine how best to mitigate the rock, a CDOT news release said.

There was no word when the traffic will be allowed through Glenwood Canyon in either direction.

Colorado Gov. Bill Ritter has declared a disaster emergency for the 17-mile stretch of I-70.

CDOT crews began removing debris from I-70 in both directions at the Hanging Lake Tunnel. Work included drilling holes in the boulders to insert explosives and blast them into smaller pieces to be hauled away.

The interstate remains closed between Glenwood Springs (Exit 116) and Dotsero.

CDOT engineers said that clean up would continue over the next two to three days, and that they hope to have an emergency contractor by the end of the week to begin repairs.

However, when the interstate would reopen is still unknown. Elsen would not say how soon traffic may again be allowed through the canyon.

Elsen did say that damage to the road was severe, and he estimated that repairs could take between two and three months to complete.

“Without knowing anything else now, this is probably a two-month repair,” Elsen said.

Cottonwood Pass not an option A statement provided by Eagle County addressed questions concerning Cottonwood Pass. The closure of Interstate 70 through Glenwood Canyon generated several requests that Eagle County open Cottonwood Pass to through traffic. While it does appear on local maps, the gravel road is not maintained for winter travel. According to Brad Higgins, Eagle County's director of Road and Bridge, Cottonwood Pass, which connects Gypsum to Cattle Creek south of Glenwood Springs, closes every winter from the end of November until mid-April. “Cottonwood Pass has never been maintained in the winter, nor is it designed to handle a high volume of vehicles, so to simply open it to traffic is not an option,” said Higgins. “Ice and snow accumulate on the sides of the road and create large ruts, making it impassable for regular passenger vehicles or tractor-trailers as well as making it too narrow for two-way traffic.” Snow slide on railroad tracks Railroad authorities reported that although the rock fall near Hanging Lake did not affect their rail corridor, a snow slide near the eastern end of the canyon on Monday did cover the tracks. Mark Davis, a spokesman for the Union Pacific Rail Road, owner of the tracks, said it was unknown as of around 4:30 p.m. when the track might be cleared. He said the railroad emergency management crews were just being dispatched to the scene to check out the slide. Newspaper Delivery With the Glenwood Canyon closure, the delivery of the Glenwood Springs Post Independent and Aspen Times could be delayed. The newspapers are printed at the Colorado Mountain News Media press plant in Gypsum. Delivery trucks will now travel through Steamboat Springs and down Highway 13 through Meeker into Rifle. The longer delivery route has also prompted the newspapers to move up their press deadlines in an attempt to get the newspapers to the readers in a timely fashion. — Staff Reports See postindependent.com for updates on this story throughout the day.

According to the news release issued Monday night, work was halted around 6:30 due to darkness, but CDOT maintenance crews made good progress breaking up and clearing away the boulders.

The rock fall occurred around midnight Sunday. No vehicles were involved in the fall and no one was injured, according to the Colorado State Patrol.

The rocks made holes in the elevated sections of roadway. The largest hole measured 20 feet by 10 feet, in the westbound lanes. Another hole in the lower eastbound lanes measures 6 feet by 6 feet, CDOT reported. Both westbound and eastbound lanes were blocked by boulders Monday, some of them the size of a tractor-trailer. The largest boulder was estimated to weigh approximately 66 tons.

Some of the larger boulders were blown apart with explosives Monday, before being removed. That work will continue today as well.

Elsen compared this rock fall to the 2004 Thanksgiving Day slide. According to a Post Independent news story, the highway was closed for about 30 hours after that incident.

“It's relatively the same,” Elsen said. “I don't think it's worse.”

At least one of the five steel support girders were damaged by one of the falling boulders and will need to be repaired, along with more than half-a-dozen holes in the concrete deck, Elsen said. The fall also damaged about 120 feet of steel guard rail, about 100 feet of concrete median barrier, and destroyed two sections of precast retaining walls on the westbound lanes. But Elsen was surprised that the damage was not worse.

“I'll tell you, it's a pretty tough bridge when you consider what happened to it,” he said.

Repairs from the 2004 rock slide took about 60 days to complete, Elsen said, and cost around $1.6 million. Elsen estimated repair costs would run between $1 million and $2 million this time around, as well.

A 1995 rock slide on I-70 in Glenwood Canyon killed three people (See related story).

Engineers anticipate limited access through the canyon while repairs are under way but would not give a time as to how soon that may occur.

The rock fall on Thanksgiving Day in 2004 happened in the same general area and also closed the highway. Luckily, no one was injured in that slide as well, due to a previous closure for an unrelated crash. Prior to that, a 1995 rock slide on I-70 killed three people.

CDOT has recommended the following detour routes: To bypass the closed stretch from the east: Exit I-70 at U.S. 40/Empire to State Highway 13 and back to I-70; or exit in Silverthorne and take State Highway 9 to U.S. 40 and State Highway 13; or exit at Wolcott/State Highway 131 to U.S. 40 and State Highway 13.

To bypass the closed section from the west: Exit at Rifle/State Highway 13 to U.S. 40 and back to I-70.

The Associated Press contributed to this report.