Reinventing the Paper Mill Pond Dam

Abstract Only - First dating back to 1867, the Amerbelle Mill utilized water power from the Hockanum River in the manufacture of textiles. Channelized within a raceway through the mill complex by stone lined walls, water was impounded and diverted to power the mill by the Paper Mill Pond Dam. Consisting of a 17-foot wide by 11-foot high concrete spillway, the dam, was contained within the raceway. Foundations of adjacent mill buildings formed the dam abutments and their superstructures spanned over most of the raceway channel, confining the dam to a small courtyard, making access to the dam difficult. A 2012 inspection of the dam found it to be in poor to fair condition, with numerous deficiencies.

The Town of Vernon, Connecticut received grant funding from the Connecticut Remedial Action and Redevelopment Municipal Grant Programs to redevelop the Amerbelle Mill brownfield site. In conjunction with the grants the Town elected to rehabilitate the dam to make the site more attractive for commercial development. GZA GeoEnvironmental, Inc. (GZA) was already involved with the site redevelopment, when, at the 11th hour, the Town decided the old spillway needed to be replaced and relocated. Working closely with the Town and Connecticut Department of Energy and Environmental Protection (CTDEEP), GZA proposed relocating the dam 40 feet upstream, but still in the raceway. The option was more cost-friendly for the Town and also had the benefit of reducing the dam’s hazard classification, by significantly reducing the dam height. Though the spillway width would be reduced, upstream hydraulic conditions were maintained with a more efficient ogee weir. A manually operated stop log bay was incorporated at the right side, allowing normal flow over the stop log section while maintaining the ability to draw down the impoundment.

Construction of the relocated dam began in late 2016. Much of the work was performed by hand or with small equipment due to access limitations within the 12-foot deep raceway. The dam work was performed simultaneously with the brownfield redevelopment. Through proper planning and working closely with the CTDEEP, Town, and the Remediation Contractor, the relocated dam was successfully completed by mid-2017.

Through diligent coordination and planning, GZA was able to develop an innovative solution to create an aesthetically pleasing, low-maintenance structure, while maintaining existing hydraulic conditions and reducing the structure’s hazard. The relocated dam became integral to the site redevelopment, making the overall site more attractive for future commercial redevelopment.