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Mountainous erosion

Summer storms test drainage devices along parts of Pikes Peak Highway


Rocky Mountain Youth Corps workers line a creek near - Glen Cove with boulders to help it repel stormwater. - ANTHONY LANE
  • Anthony Lane
  • Rocky Mountain Youth Corps workers line a creek near Glen Cove with boulders to help it repel stormwater.

The surges of stormwater that turned much of Glen Cove wetland into a sprawling sandbox were supposed to be a thing of the past.

To restore the area, workers planned to rescue surviving plants, haul away the gravel and sand, then replant and reseed.

An August storm changed those plans, slinging water over a detention weir (a small dam or wall designed to slow runoff) beside the Pikes Peak Highway. The stormwater carried fingers of sand more than 20 feet into a previously undamaged part of the wetland. Buckets for carrying the plants away were almost buried in fresh sediment.

"In any job, you have good days and bad days," says Eric Billmeyer, assistant director of the Rocky Mountain Field Institute, who is leading an effort to restore parts of the mountain damaged by runoff from the highway. "That was a bad day."

After years of drought, the summer's heavy rains finally tested a paving and erosion-control effort on the peak, which was intended to end decades in which stormwater ran off the highway and devoured the mountainside below, washing away trees, carving mini-canyons and pushing gravel into streams and over fragile wetlands.

The city of Colorado Springs, which operates the road under a lease with the U.S. Forest Service, has paved the most erosion-prone section of the highway, lined many drainage ditches with concrete and installed 17 detention weirs meant to tame stormwaters that have ravaged the peak during the highway's 90-plus years.

Billmeyer, touring the recently paved section of road running from Glen Cove Lodge to Devil's Playground at around 13,000 feet, has found signs of new erosion, fresh damage to healthy trees and detention weirs that have either failed or are threatened by erosion.

"I think the city has some really big challenges ahead of it," says Billmeyer.

Tackling the problem

The Sierra Club sued the city and the U.S. Forest Service in 1998, alleging gravel heaped on the 12 unpaved miles leading to the top of the highway was wreaking environmental havoc as stormwater pushed it down the mountain, a possible violation of the federal Clean Water Act.

The city settled the lawsuit a year later, agreeing to pave the upper 12 miles of the highway while installing detention weirs and other drainage structures, all at a cost of $17 million to $20 million. The Forest Service settled in 2001, agreeing to kick in money to clean up and monitor water quality on the mountain.

The city started paving in 2001. Six miles have been paved, and the project is slated for completion in five years.

Detention weirs are a crucial part of efforts to reduce erosion. The city has installed 17 of them on the mountain, each costing a few thousand dollars. They are designed to hold water from storms up to a severity expected only once in about 10 years. Water pools in the weirs and seeps out the bottom, losing speed that previously would have translated into eroded soils downhill.

Two of the weirs appear to be "breaking out" because of heavy rains this year, says Jack Glavan, the city's capital projects manager. Officials are now considering how to repair or redesign those damaged structures.

Others, he says, are functioning as planned. The project, which has so far cost $6.8 million for revegetation, paving and drainage structures, is "going pretty well," Glavan says.

In foreground, one of many eroded areas caused by - runoff along sections of the Pikes Peak Highway, above - treeline between Glen Cove and Devils Playground. - ANTHONY LANE
  • Anthony Lane
  • In foreground, one of many eroded areas caused by runoff along sections of the Pikes Peak Highway, above treeline between Glen Cove and Devils Playground.

Stormy summer

It has been a hard summer on the peak, with back-to-back storms pushing sediment into weirs and reducing their capacity to hold water. The most intense of the storms struck Aug. 7, hurling nearly 2 inches of rain on the peak in a one-hour period.

A crucial question that was being resolved this week is how fast the rain came during the Aug. 7 storm. If it all fell in 15 minutes, it would be the type of storm expected only once in 25 years. The weirs are only designed to control water from a 10-year storm, so water would logically have overwhelmed them.

But if the rain fell over an entire hour, it would only be classified a 2-year storm, in which case the weirs should have held.

Regardless of how quickly the rain fell, Billmeyer sees signs of trouble at each weir above Glen Cove Lodge. In some places, water has shoved aside boulders or simply carved a new channel around the weir. Sediment fills other weirs, reducing their capacity until emptied, while others show signs of erosion from below, suggesting they will not hold up if water keeps running over their tops.

Billmeyer kicks his foot into sand filling one weir that maintenance crews had dug out only a week earlier.

"This is unbelievable!" he exclaims with a mixture of awe and concern.

Later, he says current maintenance efforts of the weirs themselves don't seem adequate.

"I think they underestimated how much erosion was going to come down and fill their detention weirs," Billmeyer says.

Serious erosion

New culverts installed above Glen Cove direct most of the highway's runoff away from Severy Creek, an area on the mountain's east shoulder that once served as the poster child for what uncontrolled stormwater has done to Pikes Peak. In 1998, researcher David Cooper estimated nearly 12,000 cubic yards of sediment from the highway and slopes below had buried up to half of a precious wetland nestled nearly 1,500 feet below.

The eroded channels ripping toward Severy Creek eventually converge into a gully that is up to 20 feet deep and sometimes twice as wide. Even with much of the water now redirected, the channels are still collecting water, shifting the sands over a wetland that Cooper, a senior scientist in Colorado State University's Department of Forest, Rangeland and Watershed Stewardship, says took millennia to form.

Cooper plans in coming months to finish a report detailing plans to restore the wetland, but he fears sediment could bury the wetland in another 10 or 15 years if the drainage ditches are not stabilized. If that happens, sediment could endanger a population of greenback cutthroat trout, a threatened species living in the creek below.

"It's a crisis that's still unfolding," Cooper says.

Billmeyer, who has had teams of volunteers working this summer to stabilize drainages on the peak's northern flanks, says he plans to hold off his project to restore the Glen Cove wetland until next year, when hopefully the weir protecting it from uncontrolled runoff will function.

Still, looking at new channels carved beside the highway and slopes carved by recent storms, Billmeyer seems impressed by the enormity of the task ahead.

"If you were to build a road anywhere on Earth," Billmeyer says, "this would not be the place to do it."

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