Weymouth Great Pond Dam Construction to begin June 18th

Weymouth Great Pond Dam, located along Randolph Street near the intersection of Forest Street, will be undergoing construction this summer.  In 2017, Weymouth secured a $782,700 grant from the Executive office of Environmental Affairs Dam and Seawall Repair or Removal Fund. The Great Pond Dam was one of 22 projects awarded the highly competitive funding. This funding will allow the Town to address the existing infrastructure issues with Great Pond Dam and improve flooding as well as daily operations.   

To facilitate swift construction, a full roadway closure along a small portion of Randolph Street at the dam location will be implemented with an anticipated closure date of June 18, 2020.  A detour will be implemented to bypass the project area using Randolph Street to Forest Street, Forest Street to Columbian Street, Colombian Street to Park Avenue West, Park Avenue West to Main Street (Route 18), Main Street to Pond Street, and Pond Street to Hollis Street.  The roadway is anticipated to re-open in late summer.

The existing 190-foot long earthen dam currently has areas of unwanted vegetation, deterioration of the concrete spillway and sluiceway and their controls, deteriorated sections of the stone masonry culvert and attached walls that act as the dam outlet, and inadequate capacity to accommodate high water levels resulting from major rainstorm events.  The town’s design consultant, Pare Corporation of Foxboro, completed hydraulic and hydrologic analyses and geotechnical analyses of the existing dam and concluded that the existing dam has inadequate capacity to handle the high pond levels and water volumes resulting from storms greater than 50-year frequency, resulting in flooding of portions of Randolph Street and Relda Road, potentially impacting residences near the dam.

“I am excited the infrastructure improvements at Great Pond Dam will be underway this summer,” said Mayor Robert L. Hedlund. “This project is long overdue and the replacement of the culvert will prevent flooding that has been plaguing Randolph Street for years, thanks in part to a State grant and also the hard work of our Public Works and Engineering Division.”

The Weymouth Great Pond Reservoir was constructed in 1884 and serves as an important component of the Weymouth water supply system. The dam is classified as a significant hazard and is in fair physical condition. There are physical deficiencies with the dam that will be addressed through this project but the primary concern is in inadequate capacity of the spillway. The spillway and its associated culvert under Randolph Street are not large enough to accommodate intense precipitation events.

To address the deficiencies, increase the dam capacity to contain rainfall volumes resulting from major rainstorms, protect the town’s public water supply, and protect downstream residents and property, the town will replace the existing undersized outlet culvert with a larger concrete one able to pass water from Weymouth Great Pond to the downstream Mill River without flooding the adjacent streets and properties.  The spillway will also be improved to make daily operations more efficient and a new gate will be constructed.  Also included in the work will be regrading and reshaping the earthen dam to restore the original shape and fill in low areas caused by years of settlement.  Repaving and storm drain improvements on Randolph Street, as well as placement of protective stone known as rip rap will also be installed along the pond’s edge as part of this project.

This project has been partially funded by a Dam and Seawall Repair grant awarded to Weymouth in 2018 by the Massachusetts Executive Office and Energy and Environmental Affairs. Work will be performed by T Ford Company, Inc. of Georgetown.