March 2009

Willow Dam wins ACEC WI Award

Mead & Hunt was recognized with the 2009 Engineering Excellence Award for their work on the Willow Dam Road bridge, embankment, and spillway.  The bridge carries a local road over the Tomahawk River and the Willow Flowage dam in the town of Little Rice, in Oneida County, Wisconsin.  The annual competition, sponsored by the American Council of Engineering Companies of Wisconsin, provides the opportunity to highlight and celebrate achievements in engineering.

Mead & Hunt provided design services to replace the deficient and functionally obsolete single–lane bridge above the high–hazard Willow Dam, including reconstructing wider approaches atop the dam embankment.  The Willow Dam and its reservoir were determined eligible for the National Register of Historic Places in 1991 as part of the Wisconsin Valley Improvement Company (WVIC) reservoir system.  The reservoir system played a significant role in developing the region’s pulp paper and hydroelectric producing industries.

The project goal was to safely accommodate traffic, replace a structurally deficient bridge, reduce long–term maintenance expenditures, and maintain the hydraulic capacity and performance of the dam and connected spillway.  These objectives needed to be economically feasible, while following Federal Energy Regulatory Commission (FERC) requirements, and preservation and environmental regulations. 

Mead & Hunt created a safer crossing over the dam by widening the bridge and embankment and decoupling the bridge from the spillway structure, which saved money by avoiding replacement of the spillway.  Innovations included the use of micro piles on the structure foundation and carefully engineered embankment fill and drainage.  Micro piles—small–diameter steel casings drilled through the embankment fill to support the bridge abutments—and a unique embankment drainage system using materials naturally occurring in the surrounding area effectively widened the dam embankment without compromising its performance.  The new bridge and roadway enhanced the safety of this crossing and effectively improved public access to this pristine wilderness.  An Americans with Disabilities Act (ADA) compliant pedestrian trail to a fishing platform on the upstream side of the dam was also designed as part of this project, allowing a greater cross section of the population to enjoy the wilderness area. 

The structural upgrade of the Willow Dam exemplifies how engineers can develop a cost–effective design that maintains public safety despite the complexity of the improvement.  The culmination of this well–planned project is a facility that blends into the natural environment while enhancing general economics in the area through improved access. 

“Mead & Hunt’s expertise in bridge and dam design, FERC compliance, and historical issues made for a well–rounded team and resulted in a project that today exhibits a one–of–a–kind structural improvement over a high–hazard dam,” said Richard Meehan, Town of Little Rice Chairman.