Connecticut Department of Energy & Environmental Protection

Springborn Dam Removal

Background

A picture of an intact Springborn Dam with vegetation on the right downstream face and a log stuck on the crest

The Springborn Dam was built by Shakers in 1840 on the Scantic River in the Town of Enfield. Constructed with timber crib over stone masonry, this 76-foot long "run-of-river" dam was originally used to provide power to the adjacent mill. In 1901, the height of the dam was increased by the owner, the Gordon Brothers, so that the mill could be used to recycle waste wool. In August 1955, 14 inches of rain fell on the Scantic watershed, damaging the dam and the mill. The dam was rebuilt by its owner, DeBell & Richardson. By 2007, the "BB" (moderate hazard class) dam had fallen into disrepair and ownership was transferred to CT DEP. 

 

 

 

Removal

A truck next to a building during the removal of Springborn Dam in 2017

Due to the dam's poor condition, and because the dam had been identified as a fish barrier and a hazard to public safety, the decision was made in 2015 to remove the dam. CT DEEP, who now owned the dam, collaborated with an engineering firm (Fuss & O'Neill), the National Fish and Wildlife Fund, the Connecticut River Watershed Council, and several government agencies, including the U.S. Army Corps of Engineers, the State Historic Preservation Office, and the National Oceanographic and Atmospheric Administration, to determine a viable removal process. The removal process was challenging due to several factors, including limited site access and a water control plan for the dam's large watershed (67 square miles). But the process proceeded and the removal was permitted in early 2017. After construction began, additional challenges presented themselves. Significantly, the central pier of an upstream railroad bridge needed to be replaced when its deterioration was discovered during removal. The new pier and footing provide improved support for the bridge and greater resistance to scour from increased river velocities. Originally estimated to cost $3.9M, the removal project ended up costing $5.3M. 

 

 Outcomes

The 2017 removal of Springborn Dam was successful on several fronts. By removing this barrier, 2.6 miles of natural riverine habitat was restored, marking a significant ecological improvement. The removal of the dam also lowered the water elevation during normal and high-water conditions, greatly reducing the chances of flooding in the adjacent buildings. Also, a significant amount of contaminated sediment was removed from the watercourse and disposed of at an approved facility, eliminating exposure to recreationalists, downstream residents, and wildlife.

In addition to these planned outcomes, the unplanned design changes also created positive outcomes. The replaced bridge pier improved support to the existing railroad bridge and the unexpected revision to the revetment wall improved protection to the adjacent building.

 

  

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