MCCOOK, Neb. 12/20/11 (PennWell) -- Repair work at Nebraska's Red Willow Dam is ramping up, reports the Bureau of Reclamation.
SEMA Construction of Englewood, Colo., is moving equipment to the site and will soon begin hauling and stockpiling materials. Excavation of the dam is expected to begin in February 2012.
The repairs were prompted after Reclamation discovered a sinkhole in the face of the dam in October 2009. Subsequent investigations revealed further cracking through the embankment, causing Reclamation to draw down Hugh Butler Lake, which is impounded by the dam.
The bureau accepted bids for the repair work after Congressional approval of the Safety of Dams plan in August and awarded the US$15.3 million contract to SEMA in October.
The construction company is to excavate the embankment and toe drain, construct a filter/drainage blanket, place geonet composite on the excavated face of the embankment, construct a two-stage sand filter and coarse sand drain system, place geotextile on the coarse sand and gravel drain, construct a downstream stability berm, construct a two-stage filter drain in the channel and slopes downstream of the spillway and outlet works stilling basin, repair portions of the upstream dam face, and construct a toe drain system with monitoring wells.
For safety reasons, access to the construction site and travel across the dam will be off limits to the public during the construction period. A small observation area at the southwest end of the dam will be constructed and accessible by county roads from the south.
Construction is expected to be substantially complete by late 2012 with minor finishing work to continue through 2013.