Weston & Sampson conducted dam safety inspections; prepared an Emergency Action Plan; provided engineering evaluations of spillway capacity, embankment stability and seepage; and provided engineering design, permitting, and construction management services to rehabilitate the Babson Reservoir Dam in Gloucester, Massachusetts.
The dam had been heavily overgrown with trees and brush, and the spillway capacity was considered inadequate for the current regulatory design flood. The focus of the design was to improve spillway capacity and embankment stability for this important component of the city’s water supply infrastructure. Spillway capacity needed to be balanced with managing the risk of flooding downstream through a developed section of the city. We performed detailed hydrologic and hydraulic analyses to evaluate suitable combinations of changes to the spillway weir length, spillway location, and dam crest elevation to safely pass the spillway design flood. We also prepared inundation maps for flooded areas to evaluate social and environmental impacts of flooding due to a dam breach. These analyses formed the basis for selecting the final geometry of the repaired structure. A baffled chute spillway system was ultimately selected, designed, and constructed as part of the rehabilitated structure. The original dam construction included a reinforced concrete core wall within the embankment. The core wall was extended vertically to form the functional dam crest as part of the rehabilitation.
As part of our services, Weston & Sampson successfully applied for funding for the project on behalf of the city through the Massachusetts Executive Office of Energy and Environmental Affairs. As a result, the city received $1,000,000 in combined grant and low interest loan to be applied to the cost of design and construction of the repairs.