Hoppin Hill Reservoir Dam – High Hazard Dam Rehabilitation

Weston & Sampson provided engineering analysis, design, permitting, bidding, and construction management services associated with the rehabilitation of Hoppin Hill Reservoir Dam located in Attleboro, Massachusetts. Hoppin Hill Reservoir Dam is a 1,000 foot long, 27-foot tall HIGH hazard potential embankment dam owned and operated by the City of Attleboro Water Department. The dam and impounded reservoir are important components of the City of Attleboro’s water supply infrastructure. Weston & Sampson also prepared an Emergency Action for the dam based on information provided by the city and the results of an in-house hydrologic and hydraulic study.

Prior to rehabilitation, Hoppin Hill Reservoir Dam was in poor overall condition, meaning that significant structural, operational, and maintenance deficiencies were clearly recognized under normal sunny-day conditions. The downstream embankment slope was overly steep, eroded in several areas, and had inadequate factors of safety against slope and seepage instability. The concrete spillway structure and chute channel had fallen into disrepair and a circular concrete aeration basin and outfall channel associated with the low-level outlet were structurally deficient.

Rehabilitation construction began in October 2015 and included installation of a two-stage inclined chimney filter and drain in combination with downstream slope flattening to control seepage and increase overall embankment stability. Improvements were also made to the dam’s appurtenances, including replacement of the concrete spillway structure and meandering chute channel, demolition and removal of the low-level outlet aeration basin and outfall channel, extension of the low-level outlet conduit in coordination with embankment filling, and replacement of the low-level outlet control gate. Weston & Sampson also applied for funding for the project on behalf of the city through the Massachusetts Executive Office of Energy and Environmental Affairs.

Weston & Sampson continues to perform mandated dam safety inspections for Hoppin Hill Reservoir Dam, as well as several other dams and hydraulic structures owned and operated by the City of Attleboro.

Key Project Features

  • high hazard dam rehabilitation
  • water supply reservoir
  • hydraulic and hydrologic analyses
  • structural rehabilitation
  • construction grant application
  • in-house, multi-disciplinary approach
  • permitting
  • bidding
  • construction administration


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