Friday, June 25, 2021

1948 135mw Center Hill Dam on Caney Fork near Lancaster, TN


The dam was built in 1948. [Video]

Photo via details via $1.8b saved via Facebook
Center Hill Dam on the Caney Fork River in Lancaster, Tenn., discharges water from its spillways April 8, 2021. (USACE Photo by Lee Roberts)
This is one of four dams that held 1.8m acre-feet of water from a 7.01" rain event during March 27-28.
This rainfall storage kept the river level in Nashville at 40.55' instead of a predicted level of 55.7' if the dams did not exist. The flood stage in Nashville is 40'.

We can clearly see the peak in the blue line that happened in late March.


Three 45kw generators can supply an average city of 125,000 people.
The max height is 250'. The length is 2160' of which 1382' is concrete and 778' is earth.

This is a second dam that I have learned about that was built on a cave system and cost the USACE a lot of money. The first one was the 1913 Hales Bar Dam that got replaced by the Nickajac Dam in 1967.
In 2005 this dam was classified as a high-risk dam and the USACE spent 15 years and $353m to fix the foundation.

"The good news is, that it’s all fixed now. But it was a monumental engineering feat that took three steps to complete and fifteen years to complete.
"First, there was a grouting project at the main dam embankment and left rim. The contractor pumped flow-able concrete into the foundation to fill voids.
"Then there was a 2.5-feet thick foundation cut-off wall installed on the lake-side of the dam. It extends as deep as 308-feet from the top of the dam, deep into the solid-rock foundation to prevent future seepage through the limestone.
"There were also repairs made to a secondary auxiliary dam on the east side of the main dam. Some refer to it as a ‘fuse plug’ dam that would be used to alleviate pressure on the main dam if a major flood ever occurred."

For those fifteen years, the reservoir was drawn down to 18'. That left all of the recreation facilities around the lake high and dry.

I presume this is the fuse plug. It looks like this was another valley that needed a dam.

Are we seeing water that is leaking through the foundation of the dam? If so, I can't believe the reservoir is still full. Hydropower doesn't seem to be worth that level of risk.

I could not find any details (diagrams) about the work that was done. Note that the information I did find came from the press and not USACE's web site. But it was a while since the street view car drove over the dam, so it captured some of the repair work.
Street View, Aug 2013

Street View, Aug 2013

Street View, Jul 2014

And they were doing something beside the dam as well.
Street View, Aug 2013

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