September 2015
Construction completed at Shepard Pond Dam, Canton, MA
Reconstruction of Shepard Pond Dam was completed in September, 2015. Stephens Associates Consulting Engineers, LLC (SA) oversaw the project, observing construction of the spillway replacement and Dam repairs on-Site full time as resident engineer on the Town’s behalf. SA worked closely with the Town's general contractor, and construction was completed with less than 3 percent overrun of the general contractors bid price, well below typical industry projects. The repairs transformed the old mill dam to a modern engineered structure. SA designed an innovative labyrinth weir spillway to pass the 100-year design flood with one foot of freeboard without increasing upstream water elevations during flooding (that could have affected upstream structures) and without significantly increasing the footprint of the Dam.
To mitigate subsurface seepage and address subsurface voids identified in the borings, SA designed a grouting program consisting of low- and high-mobility grouts to be injected in the foundation and embankment, combined with replacing the top 7 ft. of the embankment with engineered fill. SA completed design plans and secured permits from the Massachusetts Office of Dam Safety, US Army Corps of Engineers, Massachusetts Department of Environmental Protection, and Canton Conservation Commission. SA also prepared a grant application to the newly-formed Massachusetts Executive Office of Environmental Affairs Dam and Seawall Repair or Removal Fund, and secured $1M in grant and low interest loans from the state, which was the largest award issued in the first year of the program.