The U.S. Army Corps of Engineers Nashville District announces Center Hill lake levels will remain lowered and targeted at elevation 630 mean sea level for 2018, and will likely remain at that level several more years until recently identified main dam spillway gate issues can be fully evaluated.
“We fully expected to raise the lake back to normal levels once ongoing work was completed; however, operability issues have recently been identified with the 70-year old main dam spillway gates that add project risk during a large flood event” said Linda Adcock, project manager.
In the early 1990’s a self-eroding structure called a ‘fuse plug’ was built into the top of the saddle dam to add the ability to safely pass a rare, extreme flood downstream.
“If the main dam spillway gates don’t operate as intended, the fuse plug on the saddle dam could operate at a smaller flood than intended,” Adcock explained.
Currently, risk of this occurrence is higher than the Corps deems acceptable. A study is underway to evaluate spillway gate repair alternatives and potential changes to standard gate operations during a large flood. The study will produce a recommended plan to reduce project risk.
Since 2008, the lake operation has been targeted 15-20 feet lower than normal throughout the year as a risk reduction measure while foundation seepage rehabilitation work has been ongoing at the main dam and the auxiliary saddle dam. Significant dam safety work at the main dam foundation is complete yet continues at the saddle dam. A concrete reinforcing berm is being constructed downstream of the saddle dam and is scheduled for completion in 2019.
The spillway gate study will evaluate an array of risk reduction alternatives. The study will take place concurrently with ongoing saddle dam repairs. Implementation of a recommended plan will likely be after 2020. Meanwhile, the lake will continue to be targeted at elevation 630 mean seal level to lower the risk of a high lake level that operates the fuse plug.
To read more on the dam safety project, visit the Nashville District webpage at http://www.lrn.usace.army.mil/Missions/Current-Projects/Construction/Cen....
(For more information about the U.S. Army Corps of Engineers Nashville District, or visit the district’s website at www.lrn.usace.army.mil., on Facebook at http://www.facebook.com/nashvillecorps, and on Twitter at http://www.twitter.com/nashvillecorps. The public can also follow Center Hill Lake on Facebook at http://www.facebook.com/centerhilllake.)