Goose Pond Dam Improvements
Canaan, N.H.
Award of Merit
Submitted by Michels Corp.
Owner: New Hampshire Dept. of Environmental Services
Lead Design Firm: Gannett Fleming
General Contractor: Michels Corp.
Subcontractors: Cascade Drilling; Geocomp Inc.; Multi-Weld; E.J. Prescott; Royal Electric Co.; Terracon
Adaptability was essential to rehabilitate this century-old, high-hazard dam, with challenges ranging from severe winter weather that delayed concrete placement and excavation to rock elevations that required use of a secant pile wall instead of the originally designed sheet pile wall.
Dewatering operations were hampered by continuous seepage, requiring modified diversion plans and installation of temporary cofferdams. Non-functioning infrastructure precluded the planned reuse of an existing wooden low-level gate system, which was replaced with a stainless-steel slide gate.
Along with rebuilding and flattening the downstream slope for stability, and installing relief wells and an underdrain system, the project also provided opportunities for innovation.
Applying shotcrete to structures where limited access and varying dimensions complicated conventional concrete repair techniques also eliminated the need for formwork and extensive bracing, saving time and costs.
The team also incorporated an advanced drainage system with high-permeability materials and HDPE pipe as well as tailored erosion and diversion controls to protect the surrounding environment.