The Hop Brook Floodwater Retarding Dam in Northborough, Massachusetts is one of nine floodwater retarding dams in the watershed of the Sudbury, Assabet, and Concord Rivers (known as the SuAsCo watershed). The dam was constructed in 1963 as a high hazard potential structure.
Supplemental Watershed Plan No. 6 – Environmental Assessment for the Rehabilitation of the Hop Brook Floodwater Retarding Dam (Plan-EA), finalized in July 2012, included an assessment of the condition of the dam. The results of the engineering analyses demonstrated that the dam is in need of rehabilitation.
Aterra is developing a rehabilitation design to meet the State and Federal dam safety and performance criteria. The proposed design includes a 680-ft wide ogee crest with Roller Compacted Concrete (RCC) stepped chute. The project includes the following tasks:
- Geotechnical investigation and laboratory testing.
- Existing structural condition investigation.
- Two-dimensional and three-dimensional Computational Fluid Dynamics (CFD) modeling to support the design of RCC stepped chute spillway.
- Preliminary design, including development of 50% design drawings and preliminary design report.
- Final design is currently ongoing and will include final design drawing, construction specifications, construction sequence, and final design report.