Dam Reconstruction Adds Aesthetic Value, Flood Protection for Minnesota Town

The high-hazard New London Dam had been on the DNR’s wish-list for renovation since the 1990s due to deficiencies including substandard embankment stability, undesirable seepage, and insufficient spillway capacity.  In addition, the dam’s outlet works, which consisted of electrically operated vertical slide gates, were not reliable and put strain on staff responsible for its operation.  Failure of the dam would likely lead to loss of life and would undoubtedly lead to severe economic impacts due to residential and commercial property damage.  Simply removing the dam was not an option as this would reduce Lake Monongalia to mud flats and eliminates what had been the identity of the city for nearly 150 years.

The Minnesota DNR finally received the go-ahead to reconstruct the dam.  It retained Stanley Consultants to prepare the design of the new dam.  Stanley Consultants was integral to the three-phase project development process from inception through completion.  Phase 1 consisted of feasibility and alternatives analyses including public and stakeholder involvement.  Phase 2 consisted of final engineering design of the selected reconstruction alternative and preparation of construction plans and specifications.  Finally, during actual construction (Phase 3), Stanley Consultants provided full-time resident engineering services as well as construction administration.

Complex hydrologic analysis and hydraulic and dam engineering design, coupled with insightful constructability planning, made development of a new dam within a very small site possible.  Construction took place with no change to the normal levels of the popular lake.  The new dam is now par with modern design standards, requires minimal manpower to operate, is visually appealing, and is a recreational attraction for the town.