Basalt applies flood mitigation lessons learned in Aug. 4 flash flood

Lessons learned from an Aug. 4 flash flood on the south side of Basalt Mountain educated a consortium of governments on what needed to be done to try to avoid a repeat performance.

A contractor for the town of Basalt is working at the intersection of Cedar Drive and Pinon Drive in the Hill District to better handle water spilling out of the Lake Christine burn scar.

“It went from flood to construction in 25 working days,” said Basalt Town Manager Ryan Mahoney.

He credited the Natural Resources Conservation Service, a federal agency, for looking at the road intersection and adapting a flood mitigation plan. The NRCS had to sign off on all work performed after the federal government awarded a $1.23 million Emergency Watershed Protection Program grant earlier in the year to Basalt, Eagle County and Colorado Parks and Wildlife.

The work at Cedar and Pinon wasn’t on the original project list. However, floodwater overwhelmed a culvert at the location and sheets of water rolled down a town street. The water peeled off where it could, inundating a handful of houses and covering numerous yards in mud and debris.

The town’s engineering consultant, SGM, proposed a solution that was approved by the NRCS. The town’s contractor tore up the pavement at the intersection and on Pinon right below. While repaving, it created a swale or valley pan — a shallow “V” — to guide the water if it overflows the culvert again. The water will be channeled across the street to a natural gully. In addition, the repaved section of Pinon will be angled to direct water toward that gully.

The $100,000 project at the intersection of Pinon and Cedar is supposed to be completed by the middle of next week.

Geri Wright, a homeowner on Pinon Drive who had concerns in August about the town’s mitigation efforts, said she was “pretty impressed” with the project.

“It seems to be a workable solution,” she said.

She said she toured the Pinon/Cedar worksite as well as other projects with Mahoney last Friday.

“I was really impressed to see how much work is being done,” Wright said.

Mahoney said the water from Pinon/Cedar eventually makes it way to Sopris Drive’s intersection with Frying Pan Road. The plan is to redirect the water, after it gets filtered of sediment, into the Fryingpan River.

Mahoney said residents along Pinon and Sopris who were affected by the Aug. 4 flash flood should be able to sleep better at night now knowing that action has been taken to direct the water. But emergency managers have warned they still need to be prepared with an evacuation plan and may want to consider protection measures on their property.

“There’s still some risk out there if we get a really big event,” Mahoney said.

He acknowledged that at least one resident of the Hill District remains critical that Basalt didn’t foresee the need for the project before the Aug. 4 flood. Mahoney said it was impossible to foresee the complete picture of how water would flow off the burn scar. The Lake Christine Fire scorched the hillside above Basalt in July 2018. The August cloudburst provided the first clues on water patterns.

He noted that a catch basin constructed on town-owned land above the Basberg Townhouses performed as planned, preventing tons of mud and debris from slopping into town. Eagle County government is using heavy equipment to clear the debris from the catch basin.

Basalt’s contractor for the flood mitigation, Heyl Construction, has three crews working on projects — one at the intersection of Pinon and Cedar, another working where a creek intersects Cedar Drive and the third on the north side of Basalt Mountain above Cattle Creek.

The consortium of partners wants to complete the work at Sopris Drive and Frying Pan Road, and another project above the El Jebel Mobile Home Park this fall.

“It’s all coming together,” Mahoney said.

scondon@aspentimes.com

via:: The Aspen Times