By Allen R. Orsi, P.E. Managing Engineer at Pare Corporation and a member of the Association of State Dam Safety Officials
It is a wonderful feeling when a vision comes to fruition, especially when it has taken years for the project to be completed. The removal of the Old Mill Dam in Bellingham, Massachusetts is a good example of what can be accomplished through strong project partnerships. Pare Corporation and the Town of Bellingham began conversations in 2008 about the future of the Old Mill Dam, which was found to be in poor structural condition. At the time, the dam was classified as a ‘significant hazard potential dam’ by the Massachusetts Department of Conservation and Recreation (MADCR) Office of Dam Safety.
Upon completion of several studies and evaluation of the benefits of dam removal versus rehabilitation, it was decided that removing the obsolete dam would increase public safety, save taxpayer dollars, and improve the ecosystem along the river.
Pare worked very closely with the Town to prepare a grant application for the Massachusetts Executive Office of Energy and Environmental Affairs (EOEEA) Dam and Seawall Repair or Removal Program to secure funding for the majority of the design and permitting of the project, as well as a no-interest loan to offset the cost of construction.
Pare also worked with the Town to apply for and receive priority project status through the Massachusetts Division of Ecological Restoration (DER). Once funding was secured, Pare coordinated with DER to obtain environmental permits and draft dam removal plans that would minimize the impact of deconstruction on the environment.
For the project to be completed, Old Mill Pond was incrementally drained through partial demolition of the concrete spillway to allow for dam removal activity to be completed in a dewatered area. Roughly 2,300 cubic yards of mercury-impacted sediment were removed from the pond and permanently disposed of onsite within a special containment berm constructed beyond the level of the post-dam removal 100-yr floodplain. This approach saved significant costs to the Town associated with offsite disposal of the impacted sediment. It also effectively removed 15 pounds of mercury from the riverine habitat.
Last week, temporary construction facilities were removed, allowing for the unrestricted flow of the river through this location for the first time in more than 150 years. Fish and other aquatic life are now able to move freely along this section of the Charles River and its tributaries, which will help restore a more robust ecosystem.
As this is the first dam that has been removed along the main stem of the Charles River, the Charles River Watershed Association hopes that the project will encourage other communities to consider dam removal and environmental restoration projects along the river.