Concrete Poured for Wing-Wall-Section of New Dam

By: Cathy Vaughan

A lot of rock breaking and earth excavating has been happening at the site of the new dam on Williams Lake through July. Dexter Construction has been digging trenches for the two ‘wing-walls’ on either side of the split-spillway and excavating to bedrock so that these concrete walls can be anchored to the bedrock. Wooden forms built in the trenches for the concrete will shape the two ‘wing-walls.’

The bright blue boom arm you see on the site is part of the cement pumping system which pushes concrete through the pipe on the boom arm and into the wooden forms for the wing-walls. The boom arm allows crews the flexibility and accuracy to pour concrete farther into the construction site where they can’t quite maneuver a large, heavy concrete truck. Crews are pouring concrete into the form for the wing-wall on the north side of the split-spillway this week.

These wing-walls will eventually be covered with earth, landscaped with native plants, and disappear. The only part of the new dam design you will see is the split-spillway which keeps the lake waters to regular spring levels and safeguards against potential flooding. Check out the article “New Dam. New Design” posted on our WLCC website for a schematic of what the new split-spillway will look like.

Lake water levels will continue to fluctuate slightly from rain events and summer evaporation. Our records show that the historic high-water level of the lake was 17.79m above mean sea level. For construction of the new dam, the lake was lowered to 16.0m above mean sea level to allow for the installation of a temporary cofferdam with a water control diversion pipe with a channel into Lawson’s Creek. This system holds the lake level at 16.25m to keep the construction area dry for construction crews to work safely. This equates to a 1.54m (5′ 1″) drop in the lake.

Lake water flows continuously through this system as there is a mandated regulatory requirement from the Department of Environment and Climate Change to maintain a specific flow of lake water into Lawson’s Creek. With a combination of water flowing through the pipe, channel, and occasional pumping there will be slight variations in lake levels.

This is a temporary situation as the various construction phases work toward a late fall completion date. At that time of year, evaporation is not usually an issue and with the predictability of fall rain, the lake should begin to fill up and look like its old self again.

Cunard Pond and the Pine Bluff Islands Park community access points to Williams Lake are currently being used for your kayaking and swimming recreation. You’ll have your lake back late fall.