Debris flow closure plan for I-70 dependent on 24-hour rainfall forecast
Access to Glenwood Canyon via Interstate 70 will depend on the 24-hour weather forecast, according to a debris flow closure plan put together by Glenwood Springs city staff.
Burn scars left behind by last summer’s Grizzly Creek Fire mixed with rainfall will likely produce dangerous debris flows in the Glenwood Springs canyon.
“We have very large burn scars out there and we have reports that indicate there’s a large potential for debris flow with moisture within the canyon,” said City Engineer Terri Partch.
The Grizzly Creek Fire broke out Aug. 10 of 2020 and burned 32,631 acres in and above Glenwood Canyon.
The fire started next to I-70, forcing the Colorado Department of Transportation to close the section between Glenwood Springs and Gypsum for 13 days. The fire was considered 100% contained on Dec. 18, 2020.
Partch walked City council members through a debris flow closure plan presentation during an April 1 work session, noting that the canyon will likely close several times this summer.
“When we first started talking about this our biggest concern was to avoid what happened with the Grizzly Creek Fire where we had traffic backed up into town and we really had a hard time getting anyone out or in there,” Partch said.
“Initially, we wanted to keep traffic from moving into Glenwood from the west,” she said.
NOAA has agreed to specifically monitor weather conditions and forecasts along the burn scar locations.
Closures will be triggered if 0.25 inches of rain drops in 15 minutes, 0.4 inches of rainfall drops in 30 minutes or 0.75 inches of rainfall drops over the course of an hour.
During a flash flood watch, CDOT will have closure gates stationed at Glenwood Springs Exit 116, Canyon Creek Exit 109 and Dotsero Exit 133.
If there’s a flash flood advisory, CDOT will set up a left lane closure at Canyon Creek Exit 109 to channel traffic.
A flash flood warning would trigger a complete closure of I-70 between Glenwood Springs Exit 116 and Dotsero Exit 133.
CDOT will close eastbound Canyon Creek Exit 109 as a secondary closure after Glenwood Springs Exit 116. CDOT, Colorado State Patrol or local law enforcement would then conduct a sweep of the canyon.
An incident command post will be located at the Hanging Lake Tunnels, unless forced to evacuate which will move the command post to the CDOT office in Glenwood Springs.
Closure points will be manned by local law enforcement until CDOT can respond.
“As soon as road closures are implemented through the Canyon, Hanging Lake Tunnels will begin messaging closures to all affected local agencies as well as to message boards to the Utah State line for eastbound travel, and to Denver for westbound travel. No detour information will be posted,” Partch said, noting that those plans would be executed before major public communication efforts are taken.
“Messaging to the Utah state line and to Denver will change to include detour information after two hours,” Partch said.
At that point, Elise Thatcher, public information officer for CDOT, will start statewide messaging on all social media accounts, looping in all local cities and counties and their law enforcement agencies.
“Areas will be closed the day before any rain event forecasted to be 30% above the chance of a Flash Flood Watch within 24 hours,” the presentation states.
River guides and outfitters will be allowed access to closed rest areas at their discretion if they acquire a signed permit from CDOT and will have the option to sign up for emergency alerts. No river guide and outfitter access will be allowed if the canyon closes.
Bike paths and rest areas will remain closed until the flash flood watch expires or rainfall event passes through.
Glenwood Springs Fire Chief Gary Tillotson said he feels optimistic about the debris flow plan.
“I think we can all agree, it’s not perfect, it’s a great start and the first time we have to execute it we’ll probably have a wrinkle or two,” Tillotson said.
Tillotson said fire season could start tomorrow, but is confident that local law enforcement and government agencies are already included in the planning of anticipated closures.
“We anticipate the worst of the fire season is June, July, August and beyond. We’re going to be able to start conversation in mid April and before June have at least a draft of a plan for another closure of I-70 west of Glenwood Springs,” Tillotson said.
“That one has always caused us significant issues. Part of that one includes closing Colorado Highway 82, and that’s a different group of players. Then we’re including Pitkin County and Carbondale Police Department. Some different folks are now affected by a highway closure south of Glenwood, but it’s needed and it’s necessary.”
Reporter Shannon Marvel can be reached at 605-350-8355 or firstname.lastname@example.org.
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