Collins Company Lower Dam Removal

The Collins Company Lower Dam, constructed in 1910 as a hydroelectric dam, is located on the Farmington River, approximately 1 mile downstream (south) of the Collinsville Dam and State Route 179, in Avon, Connecticut, south of the Collinsville Town border and across the Farmington River from the Town of Burlington. In 2011, a pre-feasibility study was completed on the Collinsville Dam and the Collins Company Lower Dam to determine whether these defunct hydroelectric dams could be repowered. The study found that repowering only one of the dams was economically feasible.

In 2019, Canton Hydro, LLC began the retrofit of the Collinsville Dam for hydroelectric generation in conjunction with the construction of a fishway in order to allow passage of anadromous fish (i.e., American Shad, Alewife, Blueback Herring, and Sea Lamprey) to the upstream reaches of the Farmington River. Removal of the Collins Company Lower Dam will allow passage to the base of the newly retrofitted Collinsville Dam.

The goals of this project are to eliminate a barrier to migratory fish; eliminate an obsolete dam; remove a public safety risk; re-create a free flowing, ecologically productive, and natural river channel; and create stable and safe public access. Also as noted above, this dam removal is imperative to enable fish passage at the fishway under construction at the Collinsville Dam, approximately one mile upstream.

As part of the dam removal design process, Princeton Hydro developed a Sediment Management Plan, which involved assessing impounded sediment quality and quantity by conducting bathymetric mapping to sense elevation of top and bottom of unconsolidated sediment, and sampling and analyzing sediment for a broad range of contaminants. In addition to using the information gathered through the assessment, a professional survey and geomorphic concepts were used to determine the volume of impounded sediment and the anticipated river profile following dam removal.

Princeton Hydro completed the bathymetric surveys, hydrologic and hydraulic analysis, geotechnical engineering, construction phasing determination, demolition and blasting plans, preparation of 30%, 60%, 90% and 100% designs, and regulatory review applications.