Berry Bay Dam Rehabilitation: New Hampshire’s First Contracting Experience

The New Hampshire Department of Environmental Services Dam Bureau (NHDES) is responsible for repairing and reconstructing 278 state-owned dams. In the past, the work has primarily been performed by NHDES’s in-house, nine-person Dam Construction Crew, supported by NHDES’s dam design engineers. However, given the backlog of dams needing repair, the capacity of the relatively small Dam Construction Crew, and the potential for increased state and federal funding for dam rehabilitation, NHDES has begun outsourcing the design and construction of some of its projects to engineering consultants and construction contractors. The first of these projects was the replacement for Berry Bay Dam, which impounds Ossipee Lake, the eighth largest lake in the state. Completing this project without an upstream drawdown and within a tight time frame made this project challenging. The installation of hydraulically controlled crest gates that could be activated from NHDES offices 65 miles away added a greatly needed safety feature. What had been a manual process of adjusting individual, 200-pound, wooden stop-logs by hand to control water levels during floods would now be remotely controlled hydraulically by pushing a button or tapping on a computer screen. This article describes the project and the lessons NHDES learned that NHDES could apply to future contracted projects.