The concrete work on the walls of the spillway on the Millsite Dam Rehabilitation project at Millsite Reservoir in Ferron has been suspended. Microfractures have been found in concrete in the walls.
The Natural Resources Conservation Service is working to find a solution to the problem. This will set the spillway back from its anticipated completion date.
The floor of the spillway is finished for now. After any runoff passes this spring then the labyrinth weir will be poured. The design of the weir allows more waterflow into the spillway.
Work continues on the dam itself. The outlet works are nearing completion. Eric Dixon said a lot of the pipe is in and set in place.
There was a shut down of water and a two-day switch to the permanent connection. The culinary water for Ferron and Clawson came from the storage tank on those days. If water is needed at the power plant during those two days it will be hauled. Everything is all reconnected and water is being delivered.
After all pipes are installed the roofs will be put on the building and on the tunnel.
Cement continues to be poured upon the spillway. The leveling concrete is complete. There are seven total concrete sections in the spillway. Four of those sections are poured. After the floors are complete then the sidewalls will be poured.
The completion date for this part of the project has been extended because of additions to the spillway walls.
These additions have added a few weeks to the previous date of completion. The labyrinth weir will be poured after the run-off season this spring.
There were two change orders approved in commission meeting, one was for the drainage and the other for an added retaining wall.
Eric Luke from Nielson Construction reported the pours of concrete have been huge. There will be two more big pours of 600 cubic yards each.
“Wall Contractors is doing a heck of a job on the concrete,” said Luke. The bedrock had to be completely cleaned and re-cleaned before the leveling concrete could be laid.
After work is completed on the outlet works, the embankment work will start. The berm/back fill work began in early April.
Four feet will be added to the top of the dam. This will bring the reservoir back to the original storage capacity.
Luke explained they will be using a shouldering machine like is used for highway construction on the side of the dam. Materials are fed into the machine and it spreads them.
This will increase the speed that the fill material can be replaced on the downstream face of the dam.
They will start at the bottom of the dam and work their way up. They should be able to move 500 to 600 feet per day. There are zones as the layers are placed. The layers include coarse gravel and sand, which are put down in each pass.
Luke said, “From now until early fall there will be 400,000 yards of material to go back into place. By Nov. 2 everything should be back in place for normal use. By Dec. 1, the project will reach substantial completion with the dam and spillway complete.
Dec. 21 is the site completion date where everything will be cleaned up. Dixon said the use of the shouldering machine on the dam is an innovative idea and they are anxious to see how it works.
“This method will increase the production, we will see how it works, but I think it will work great.”
Luke said they have been doing some testing and it looks good.
Traditional methods include adding the materials with a loader and a lot of hand work. They are hoping the shouldering machine will eliminate a lot of the hand work and increase production with less manpower.
Nielson Construction management team member Mike Ziemski came up with the idea and Luke said they have looked at several ideas to get the material back on the dam. The test runs have been completed at the pit.
A toe drain has been installed along the length of the dam. This is a longer drainage system from the previous drain at the dam.
Dixon said all dams will seep a little if the water comes through clean there isn’t a worry.
“The vast majority of this dam was left in place. The toe drain will intercept and control leakage, if it works as it’s supposed to the leakage is two cubic feet per second,” said Dixon.
The chimney drain which is in place can take higher flows. These improvements to the dam will bring the dam into compliance with current dam safety standards. The new filtering chimney drain is in place should an earthquake cause a crack in the dam.
The dam will extend 100 feet farther out than the old dam. The new dam is 110 feet wider. They will flatten the slope on the back side of the dam and the earth berm added which results in the increased width. Luke said the new slope of the dam will come out to where the previous golf hole number three turned the corner by the cliff.
Cracks in concrete to delay Millsite Dam project
Millsite1