Red Willow Dam Modifications

McCook, NE

This project was the recipient of ENR’s 2014 Best Projects Award of Merit.

Located north and upstream from the town of McCook, Nebraska, the Red Willow Dam impounds water to create Hugh Butler Lake and serves primarily as a regional flood control/irrigation reservoir and state park recreational facility. This water resource project provided safety modifications to a large reservoir operated by the United States Bureau of Reclamation (USBR).  The Dam historically experienced unsatisfactory seepage through the dam slope and associated downstream slope instability, which posed a serious dam safety concern for downstream communities.

SEMA Construction, Inc. (SEMA) was the General Contractor selected for this $15 million project.  The principal components of construction included: excavation of 400,000 cubic yards from the entire downstream face of the embankment to the top of the existing sand blanket for major embankment reconstruction; removal of the existing toe drain and seepage monitoring system and extending the existing sand blanket to an improved toe drain seepage management system; placement of geonet composite on the excavated embankment slope for seepage control; construction of a new, two-stage filter chimney drain zone to capture and manage future seepage; reconstruction of a more stable embankment slope that included a downstream stability berm and buttress and reconstruction of the discharge basin below the spillway and outlet works.

Back to Projects