Back to CW Lake Major Rehabilitation

Release No.: 13-06
Contact: James Beard
Phone (573) 223-7777

FIRST PHASE BEGINNING ON CLEARWATER DAM REHABILITATION

PIEDMONT, Mo., March 14 – The first phase of the Clearwater Dam Major Rehabilitation Project will get underway this month. Over the course of the next four years or so, a concrete cutoff wall will be built through the dam into the bedrock to make the dam good as new and keep it safe for many years to come.

Phase I work will be performed by Advanced Construction Techniques, Ltd., of Kettleby, Ontario, Canada. Work will consist of investigative drilling and grouting along the length of the dam to determine the condition of the bedrock beneath and help define how deep the cutoff wall will be constructed.

Phase 1 is expected to take about 15 months to complete, and Advanced Construction may work multiple shifts and weekends. The firm will employ about 20 workers and will set up a local office that can be contacted for information about employment or other opportunities to do business.

The highway across the dam will remain open, though there will be heavy equipment and increased traffic in the area. We ask all visitors and those who use Highway HH on their commute to be alert for dump trucks, heavy equipment and construction personnel.
As work progresses on Phase 1, the Phase II contract will be awarded in early to mid 2007. During the second phase, the cutoff wall itself will be constructed. This phase is expected to last about three years.

The project is the result of an in-depth study conducted after a sinkhole was discovered in the dam in January 2003. The sinkhole, which was 10 feet across and eight to 10 feet deep, was re-filled with compacted clay. No significant settling has occurred since, though engineers involved in the study concluded that as water continues to seep under the dam, the dam’s stability could eventually be threatened.

The study looked at many alternatives to correct the seepage. Some seepage under earthen dams is normal. However at Clearwater, the concern was that seepage over the long-term was causing the movement of materials from the embankment. The study report recommended construction of a concrete wall the length of the dam to control ongoing seepage and eliminate the risk of new sinkholes.

A cutoff wall is basically a deep trench excavated in the soil and bedrock into which concrete is placed. The result is a structural wall that will cut-off the subsurface seepage flow. The wall will be constructed along a line about 100 feet toward the lake from the centerline of the dam, on top of the existing berm. Therefore, Highway H-H will remain open to traffic.

Lake levels will not be affected. The lake will continue to be operated according to the approved operating plan. Recreation will be unchanged, with the exception that the Information Center has been relocated to the Clearwater Project Office to make room for the Corps’ construction office. Once the project is completed, the Information Center will revert to its normal location.

For more information regarding recreational opportunities at Clearwater Lake, write the Corps at RR 3 Box 3559D, Piedmont, MO 63957 or call the Clearwater Project Office at 573-223-7777.

Other general lake and agency information can be retrieved from the Internet at
www.swl.usace.army.mil/parks/clearwater.

For future lake levels and river conditions check the Lower Mississippi River Forecast Center at http://www.srh.noaa.gov/lmrfc/forecast/tributaries/status_black.shtml and the Corps of Engineers Water Control Data System at www.swl-wc.usace.army.mil/.