Soil and water

How experts are trying to deal with Glenwood Canyon mudslides that close Interstate 70 – CBS Denver

(CBS4) – Once again on Sunday, mud cascaded over Glenwood Canyon, forcing Interstate 70 to close for the second time on a busy summer weekend in Colorado. The slides closed a major artery to and from the West Slope and made the people of Glenwood Springs wait again.

The storm had prepared the crews for days.

“The Grizzly Creek rest area had already been closed for two days in anticipation of this,” said Jonathan Godes, Mayor of Glenwood Springs.

On Saturday, the highway was closed for more than seven hours as crews cleared a slide more than 70 feet wide and 5 to 7 feet deep.

Get used to it.

The 2020 Grizzly Creek fire has not finished wreaking havoc.

“In a place like Glenwood Canyon where you have limited access and communication in terms of cell phone coverage, and that thing, it’s a tough environment,” said Bob Group, CDOT’s Geohazards program manager.

The group and their team try to navigate difficult slopes to see the potential risks, but in the canyon it is not easy.

“Each situation is unique,” ​​he noted.

There are many issues that CDOT teams look at when examining slip hazards.

“There’s the severity of the burns, there’s the soil conditions, there’s the topography, there’s the intensity of the precipitation. There is the duration of precipitation. And all of these things come together, ”Group said.

Part of the overheated soil has been burnt so that it no longer absorbs water. This is called a hydrophobic soil.

“There are the root systems that are in place, but then there is the aspect of fire which changes the nature of the soil itself and makes water infiltration more difficult. Water that would have sunk in the ground before has nowhere to go, ”Group said.

Except at the bottom.

In some places in Colorado, mitigation efforts can help.

“You can have settling ponds that you can set up. There are the debris barriers that you can put up and they are basically large steel mesh strainers.

But in Glenwood Canyon, they won’t really do the job on the 30,000 acres of Grizzly Creek fire burns.

“Both of these require a footprint in a sufficiently large and sufficiently flat area,” he told us.

And for mesh strainers, “you really want these installed in an area where you have access to service them because a single event can often fill them up.” “

But access is not easy in the craggy Glenwood Canyon.

“Our spinoffs are Grizzly Creek and No Name – these drainages are our raw water intake,” Glenwood Springs Mayor Godes said.

The city had to make some quick adjustments.

“There is so much debris and turbidity and all kinds of nasty things that have fallen that we have had to shut down our raw water intake and rely on the existing water stocks that we have in our tanks and in the factory. water treatment at that time. “

Glenwood’s 6 million gallons of storage would be fine in winter when water consumption is about 1 million gallons per day, but not in summer when it increases to about 4 million gallons per day, mainly due to l watering lawns.

The City issued a message early Sunday morning asking people to stop watering the lawn.

“We had to send it because we needed this irrigation to stop,” said Godes.

The slide on Sunday night was worse.

“We had to extend the outdoor water restrictions until June 30 because one of the slides hit our water intake. It’s actually a much bigger event than yesterday, ”Godes said on Sunday evening.

Glenwood Springs also draws water from the Roaring Fork River, which flows into Glenwood Springs from Pitkin County, taking water from the Crystal River with it. The water quality isn’t quite what Glenwood Springs already gets from Glenwood Canyon, but it has worsened in recent years.

“There was a huge fire 3 years ago, the lake Christine fire in Basalte, and it was a fairly extensive thunderstorm yesterday and we had a lot of debris flows from that burn scar that went produced 3 years ago. “

Glenwood Springs is studying long-term water demand and could potentially change landscaping rules, Godes said.

“Lawns are just a huge sucker for water,” he explained. “We’re going to look at this through our municipal code. “I think the future will be for communities like Glenwood Springs, is that we won’t be able to have lawns the size of a golf course or conditioned.”

But he also thinks less forest fires would help. Many, including the Grizzly Creek fire and the Christine Lake fire, are man-made.

“If we can avoid the Christine Lake Fires, the Grizzly Creek Fires, or the current fires that are active right now in and around our town, the Oil Springs Fire and the Sylvan Lake Fire, it is is probably the best of the two. ”

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