The Colorado Department of Transportation plans to spend more than $4 million to prevent erosion along Highway 24, particularly in the Rainbow Falls area.

Work is expected to begin in early May, said CDOT Resident Engineer Dave Watt.

The state Transportation Commission approved the spending from its contingency funds in September, with $4.2 million targeted for flood mitigation along Highway 24. Nearly $600,000 went for project development and right-of-way acquisitions.

“We’re trying to complete the design work quickly,” Watt said. “We’re responding as if it’s an emergency. We want the work done before the rains hit.”

The Waldo Canyon fire burn scar increases the chance of flash flooding, because rain won’t soak into the burn area. Instead, it flows down the hill, attracting sediment and debris along the way.

Stabilizing slopes on the north side of the highway are a priority, along with installing sediment traps and cutoff walls. Improving drainage with expanded culverts is another goal.

“We want to stop debris flow on the north side of the highway and improve the water flow to Fountain Creek,” Watt said.

About $750,000 will be spent to stabilize the Fountain Creek embankment and prevent erosion south of the highway below the Rainbow Falls bridge.

“With the height of that embankment, if we had a bad erosion problem, it could close the highway for a while,” Watt said.

Highway 24 was closed for about 12 hours after a mud slide covered part of the road following a July 30 rainstorm. Experts called that an “annual” rain event but it caused more problems than usual.

“That’s the main slide area,” Watt said. “The whole area will be sensitive for several years, maybe up to 10 years.”

Informational signs will be added along Highway 24.

“That will allow us to spread the word in case stormwater events are anticipated,” Watt said.

No amount of mitigation can make the problem disappear, though.

“This isn’t foolproof but it gives us a better chance of keeping the highway open,” Watt said. “The goal is maintain a reliable Highway 24 to benefit the Ute Pass and Cripple Creek areas.”