Evaluating Options for Water Quality Improvement
Our firm is providing services for the removal of Upper and Lower Bemis Pond Dams on Abbey Brook within the City of Chicopee’s Szot Park to avoid possible dam failure and improve ecological conditions. The lower dam is classified as having significant hazard potential and both dams contribute to poor water quality. Bacteria is an issue in the brook, in part due to the high presence of geese within the park. Removal of the dams will improve water quality, encourage new native vegetation growth, and improve community resilience to flooding within an underserved population center.
Our firm partnered with the City to perform a feasibility study in 2020 in order to to evaluate the potential restoration of Abbey Brook. The evaluated reach of Abbey Brook included two dams in Szot Park, a roadway culvert, and a 250-foot-long culvert that outfalls to the Chicopee River. Our engineers performed the full design for removing the lower dam and improving Szot Park. Our scope of work included an evaluation of alternatives for removing the lower dam, for removing both the lower and upper dam, and for removing both dams, daylighting the downstream culvert, and increasing the size of the Front Street Roadway culvert.
A topographic and bathymetric survey was performed that included wetland resource areas subject to local, state, and/or federal jurisdiction within the area identified. Sediment samples were collected and tested for a variety of analytical parameters to evaluate potential off-site disposal options and approximate disposal costs.
A hydrologic/hydraulic analysis was performed to evaluate the capacity of the dams and culverts. Flows were determined using a rainfall runoff model, and potential future climate change was evaluated by increasing the precipitation depths using methods outlined by the U.S. Global Change Research Program. A steady state hydraulic model was developed from the Chicopee River to approximately 0.5 miles upstream of the upper dam.
Design elements include stream channels at the locations of the existing dam impoundments as part of the dam removal evaluations. The proposed design included grade control Step Pools and Riffle Grade Structures to provide elevation controls for the proposed restored stream.
The project includes a significant public education and engagement component to bring park users closer to the river to inform them about the importance of river health, water quality, and the ecological and community benefits associated with dam removal. The dam removals are currently under construction.
Services Snapshot
Tighe & Bond provided design, permitting, and construction phase services to the City of Chicopee in support of the Upper Bemis Pond and Lower Bemis Pond dam removals.
