The City of Chelsea maintains a stormwater pump station, which discharges via a 30” steel force main to a large diameter culvert scheduled for abandonment. The force main exists in a densely developed utility easement, and the culvert and force main are each located in known areas of soil contamination. The city also suspects that the existing discharge piping might be incorrectly sized.
Weston & Sampson provided design, permitting, and bidding services to replace the discharge force main and re-route the outlet to an alternative existing drain culvert. As part of this project, our work includes implementing flood resiliency measures to protect the critical stormwater pump station. Inundation maps incorporating the anticipated effects of climate change estimate the 50-year storm in 2030 will exceed the pump station’s top slab elevation, and the 3-year storm in 2070 will exceed the pump station’s top slab elevation. The scope of work includes:
- Approximately 1,400 feet of new stormwater force main in Second Street
- A discharge structure at the Spruce Street culvert
- Abandonment of the existing stormwater force main
- Flood resiliency improvements at the Carter Street Pump Station (i.e., a wall around the perimeter of the pump station and a surface drain system to remove water captured within the enclosed perimeter)
Under a separate contract, Weston & Sampson is assisting the city in designing internal improvements to support resiliency, including sluice gate and check valve replacement.