GLENWOOD SPRINGS, Colo. — As the Grizzly Creek Fire continues to smolder in Glenwood Canyon, the Colorado Department of Transportation (CDOT) prepares for what could happen along Interstate 70 when rain falls over the burn scar.
“Maybe not quite debris flows, but smaller rockfalls or smaller rockslides that will occur," said Ty Ortiz, geohazards program manager for CDOT.
Ortiz and his team manage geologic hazards that affect roadways in Colorado. On Monday, Ortiz took a ride in a helicopter high above Glenwood Canyon to get a good look at scorched terrain.
“Such a beautiful canyon, and to see all the damage to it was a little heartbreaking," he said.
Ortiz said he couldn't recall a wildfire that burned so close to the interstate. As of Tuesday, the Grizzly Creek Fire had reached 32,464 acres and was 75% contained.
Ortiz said it won't take much rain over the burn scar to get the soil moving and take some debris with it. A quarter-inch of rain over 15 minutes could trigger a slide and a potential closure of I-70.
“If those storms look like they have that rate of rainfall, and they’re headed towards the canyon, then [CDOT] could respond in terms of a canyon closure before that storm gets there," Ortiz said.
The first few rain events will be key, Ortiz said, and will guide CDOT's response in the future. Ortiz said CDOT was in the design phase of installing new protective fencing along I-70 in Glenwood Canyon.
Ortiz said CDOT had previously installed 30 rock-wall fences in the canyon, some of which were partially melted or charred in the fire.
The plan is to install additional fencing sometime in the fall, Ortiz said.
“What the helicopter ride told us is that we probably want to modify the design of those lightweight fences to make them a little more stout because it just appears intuitively that we’re going to get more than just small rockfall on the road," he said.
Outside of fencing, a spokesperson for CDOT said the ability to mitigate debris flow immediately above I-70, "will be minimal due to the steepness of the slopes."
CDOT will closely monitor the next few storms in the area, knowing the scarred canyon will likely be impacted for years.
“For several seasons now, we’re going to have debris flow concerns and likely rockfall concerns as well," Ortiz said.
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