Tag Archives: Pare Engineering

The Removal of the Old Mill Dam along the Charles River in Bellingham, MA

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.

Pare Gets Resilient!

Pare’s Ryan McCoy Presents at the ASCE COPRI Coastal Structures Conference in Boston

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From September 9-11, 2015, Ryan McCoy, a project engineer with Pare’s Waterfront/Marine team and co-chair of the Pare Climate Change Committee (PC3), attended a 3-day conference in Boston, Massachusetts hosted by ASCE-COPRI (Coasts, Oceans, Ports, and Rivers Institute). The “Coastal Structures and Solutions to Coastal Disasters Joint Conference” highlighted resilient coastal communities focusing on coastal protection and the vulnerability of the coastal infrastructure to coastal storms. In addition to attending technical sessions with topics ranging from coastal storms and flood mapping to tsunami response and protection to climate change and sea level rise, Ryan presented on day 2 at the conference’s poster session. Ryan discussed the Salisbury Tide Gate project, highlighting the resiliency of the structure which was designed by Pare with construction completed in 2014.

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Oxford dictionary defines Resilient as “able to withstand or recover quickly from difficult conditions.”   The Salisbury Tide Gate project exemplifies the resiliency that is required when future sea level rise and the intensity of coastal storms are unknown. Pare reviewed available data including FEMA flood maps which indicated a 100-year flood elevation several feet above the embankment’s crest. In lieu of raising the crest elevation of the entire embankment (over 1 mile long), Pare incorporated resiliency into the embankment and tide gate design by allowing the site to be overtopped during significant storm events. Pare’s engineers designed the structure to be reliable and robust in order to preserve the structural integrity and water control required for post-storm recovery.

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The reconstruction of the site included the reconstruction of the embankment, replacement of the single culvert with twin culverts, and the installation of new tide gates. In order to make the site resilient, the new design included the installation of a steel sheet pile core wall driven to effectively eliminate seepage through the embankment, installation of armor stone on both sides of the embankment to reduce the effects of erosion potentially caused by flood waters, setup of remote water level sensors upstream and downstream of the embankment to alert DPW employees to rising flood waters, and new tide gates designed as combination sluice/flap gates to provide additional water level control during predicted flood events. In addition to these hard and fast solutions, proper tidal exchange and flushing of the sensitive salt marsh was reestablished, which restored the health of the resource area and provided a natural buffer during storm events.

These types of design considerations are going to be required as coastal communities look to improve public or private infrastructure across the country. Pare’s Climate Change Committee has worked diligently to understand the effects that climate change may have on future projects and the civil engineering industry as a whole. By remaining current with the science and policy of climate change, PC3 and Pare will provide our Clients with knowledgeable recommendations to mitigate the potential impacts of climate change through resilient design that is adaptable to a dynamic environment.