Culvert and Dam Outlet Structure Replacement

Hydrologic/Hydraulic Analyses, Design, Inspection, and Construction Administration for Outfall Replacement

Washington Street Culvert Replacement

When the Washington Street Extension culvert, which is a 72-inch corrugated metal pipe that carries the Neponset River under a town road, began to fail the roadway over the culvert began to partially collapse. The Town of Walpole selected Weston & Sampson to provide engineering services for the replacement of the culvert.

The project involved several unusual challenges. First, the narrow road over the culvert is the only access route to several homes. Second, the existing culvert provided very little cover for the utilities serving homes on the road, and a planned sewer extension would require the use of pumps to serve these properties. Perhaps most importantly, the culvert would be installed in the environmentally sensitive Neponset River, and the design would have to minimize the impact on the river.

Weston & Sampson coordinated with the local Conservation Commission and obtained the required permits and a temporary access road was constructed across several private properties to allow residents and emergency vehicles to reach the homes during construction.

The project was funded by the State of Massachusetts under the Transportation Bond Bill. Construction was completed within a shortened schedule, and both construction and engineering services were completed under budget.

Mill Pond Road Culvert Replacement/Turner Pond Dam and Outlet Structure Replacement

The Town of Walpole selected Weston & Sampson to design the replacement of the Mill Pond Road culvert and the Turner Pond dam and outlet structure.  When the water level in Turner Pond dropped significantly as a result of the dam deteriorating, the existing culvert deteriorated and the outlet level control structure failed. The road over the culvert is the only access route to several homes. Complete failure of the culvert would have isolated many of these homes.

A portion of Mill Pond Road, where the culvert crosses through, met the requirements of Massachusetts General Laws (M.G.L.) Chapter 302 for the definition of “Dams.” As a result, this project was subject to the Massachusetts Department of Environmental Management (DEM) Regulation 253, “Dam Safety.” The Mill Pond Road culvert is unusual in its special inlet and outlet conditions. The inlet to the culvert acts as an overflow weir to control the water level in the pond, and the culvert itself acts as the spillway to the Turner Pond dam. A second level control structure at the inlet to Turner Pond had also deteriorated.

Weston & Sampson's design included a new 24-inch bypass and low level drain to meet DEM dam regulations. We replaced the existing irregular flat-bottomed oval culvert with a 4-foot by 8-foot precast box culvert with a level control structure. We also considered support and reconstruction to the embankment along the downstream side of the dam. To eliminate future impact to the dam, our contract included provisions to allow future sewer service of the homes beyond the dam.

In addition to our design and the completion of a Notice of Intent to the local conservation committee, Weston & Sampson obtained the required Army Corps of Engineers permits and completed a Water Quality Certificate required for this project.


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