Construction To Begin On Project To Minimize Flooding In No. 1 Canyon

Construction is set to start next week on four flood basins in No. 1 Canyon just west of Wenatchee in the Cascade Mountain foothills. 

The canyon has been prone to flooding that leads to heavy runoff of mud and debris during high intensity storms. 

Chelan County Commissioner Kevin Overbay says constructing the flood basins involves a lot of heavy lifting. 

"This is basically an earth moving project that we're going to move about 10,000 cubic yards of dirt from the site," said Overbay.  "And about 400 loads of rock will be brought in by dump truck." 

When built, the basins are designed to capture and release the flood flows downstream with minimal damage to homes and property. 

Both No. 1 and No. 2 Canyon Roads were closed for a week to let crews clean up debris after a heavy storm brought flooding in early June. 

A consultant for the Chelan County Flood Control Zone District designed the four basins, which are about to be built on 21 acres at the end of No. 1 Canyon Road. 

They'll complement a series of detention basins that were built lower down the canyon in 2015. 

Over the last several years, those much smaller basins have been effective in decreasing the amount of sediment entering the City of Wenatchee's storm water system, with the sediment being replaced with an increase in the volume of water. 

Overbay says the new, large flood basins will provide additional protection for homes and property during intense conditions. 

"What will happen is when we have rapid snow melts or any sudden rains or anything like that, the water will fill each one of those basins and move to the next one," Overbay said. "It not only slows down the water, but it actually deposits sediment in the bottom of the basins, that is then, after the event, cleaned out by our public works department."  

The project will allow the debris from storm runoffs to be deposited within the basins and overflow channels before it could cause a system failure downstream. 

Construction of the project will cost about $1.3 million. It will be paid for with a nearly $1 million grant from FEMA and with money from the county's Flood Control Zone District funds.