Mount Charleston flood berm halfway done
Work is more than halfway done on the earthen berm that will divert floodwaters away from the Rainbow subdivision on Mount Charleston.
Officials expect the project to be finished in December.
The project is intended to prevent further damage to the mountain community, which has been hit with flooding twice in the past two years.
The construction crew is working 12-hour shifts, laboring 13 days out of every 14, to get the job done.
“We’re working straight through Thanksgiving,” said Michael Balen, a lead engineer with the U.S. Forest Service. “We’re not taking the day off.”
To create the berm, earth-moving equipment removes dirt, reshaping the contour of the mountainside to carry the water downward.
Work is proceeding on both ends of the berm, with equipment transporting earth from one end to the other as it is transformed from a hillside to earthen walls lined with stones to divert water.
“Everything’s going to meet in the middle,” Balen said.
The project started Oct. 10 with tree removal. Boulders are being placed to prevent erosion along the bottom of the berm and the upward slope that rises several feet above the bottom.
All the earth-moving and rock placement is expected to be finished before Thanksgiving. The final phase — putting grout, or cement, between the rocks — will start sometime around the holiday.
When cement is poured between the rocks, it will smooth out the bottom, allowing vehicles to travel for maintenance work, including the removal of debris and obstructions.
Rocks near the top of the sloped edges will be kept rough, to keep the water flow limited to a speed of 23 feet a second.
Forest Service staff are building the project, and the Corps of Engineers is the construction manager.
“They are still working very, very aggressively to keep the project on schedule,” said Anne Hutton, chief of the Corps’ Emergency Management Office for the Los Angeles District, which encompasses Mount Charleston.
The Army Corps of Engineers developed a plan that was ready to go in June, but the deal between Clark County and the federal government fell apart when county attorneys didn’t want to take on the legal liability for the berm, which is being built on Forest Service land.
The state reached an agreement with the Corps after Gov. Brian Sandoval toured the area in August, shortly after a July 28 flash flood hit the subdivision.
The $3 million project is intended to divert water away from the housing and safely down the mountain.
Flooding wasn’t an issue at the Rainbow subdivision until after the Carpenter 1 Fire in 2013, which destroyed almost 28,000 acres, including much of the vegetation on higher ground above the homes. The area also was hit hard by flooding in September 2013.
This year’s flood washed out county roads and damaged water lines with about $1.4 million in damag.
It also hit 10 homes with damage estimated at $849,000, according to the county. Some of the homes were filled with mud and debris.
The project has changed in size since it was planned earlier this year. It had a preliminary design length of 1,200 feet. The length was increased to 2,350 feet to protect more homes after the Corps heard feedback from residents and extended it to add a greater degree of protection to 15 of the homes.
The berm is designed for a 25-year flood event, which has just a 4 percent chance of being equaled or exceeded in any year.
Officials will remove the berm after sufficient vegetation grows back.
“They’re working really hard,” said Becky Grismanauskas, one of the residents who voiced sharp criticism when the county didn’t accept the proposal from the Corps and flooding hit.
Contact Ben Botkin at bbotkin@reviewjournal.com or 702-405-9781. Find him on Twitter: @BenBotkin1.
