Major Flood Control Project Underway in Logandale

By VERNON ROBISON

The Progress

Construction is underway on a public works project that promises to solve perennial flooding problems along Whipple Ave. in Logandale. The $20 million project consists of the installation of a storm drain system all along Whipple Ave. and a large detention basin in the wash just north of the Clark County Fairgrounds.

The project, which commenced earlier this year, will include a 20-foot high earthen dam with a concrete spillway. This structure would span about 200 feet across the wash to retain flood water.

“The project is centered around the dam to retain the floods here,” said Logandale resident, Mike Terril, project manager for CG&B Enterprises Inc., the contractor on the project. “Any flood water runoff that comes down the wash, usually comes out and floods the fairgrounds and Bowler Elementary school. So that is a big part of what we are solving here.”

According to Terril, construction crews will be moving more than 50,000 cubic yards of material to build up an earthen embankment for the dam. The spillway over the dam and the flatwork done over a large portion of the earthen embankment will include about 4,000 cubic yards of concrete.

“It has to be built in a manner that meets national dam safety standards,” Terril said. “This is considered waters of the U.S., so the specs require it to be not just a flood control structure, but like a dam that retains water.”

Terril explained that flood waters coming down the wash would build up behind the dam. An outlet structure takes that pooled water and carries it underneath the dam through a 36-inch concrete pipe leading south through the desert to Whipple Ave.

From there, the drainage system heads west beneath Whipple Ave. The water will drain through a series of progressively larger pipe segments and eventually larger box culverts. Along the way, inlets will pick up flows from various other cross streets and drainage points.

One of the key inlets will come from a low point at the intersection of Lyman Street and Burt Circle. This is a traditional trouble spot for flooding.

“That is a place that always turns into a swimming pool,” Terril said. “This project will put that pool of water run into a drop inlet about where the existing inlet is. But a bigger pipe will take it down and dump it into the box culvert.”

Eventually, the main flow will continue west along Whipple Ave, pass beneath Moapa Valley Blvd., and continue to flow into the Muddy River. By the end, the water will be travelling through a 12’ x 6’ box culvert to accommodate the flow. Crews are currently working at the west end of Whipple near Mahalo Circle installing that culvert.

Terril said that the most challenging part of the project will be installing the drainage system along Whipple Ave.
“Whipple is a pretty busy street,” he said. “We will have traffic control through the area with some flagging during the day to get people around where we are working. Then at night the lanes will be opened up again. So it will impact the people coming down Whipple.”

Terril was quick to point out that the project crews will have their hands full on the west side of Moapa Valley Blvd until well after the Clark County Fair takes place. Thus the project will not affect traffic throughout the week of that major event.

Another big challenge to the drainage system is the depth required for the pipe installation. The box culvert will need to be installed at average depths of 15-20 feet. The maximum depth of the project is about 25 feet deep on its western end.

“Putting in box (culvert) at that depth is always a challenge,” Terril said. “You have to take your time and make sure that everybody is safe.”