About this Project:
This Project was developed as an interim improvement to enhance MWRA’s emergency response to a failure of the Metropolitan Tunnel system until a redundant tunnel is constructed. The Project is to replace pressure reducing valves on the Weston Aqueduct Supply Main (WASM) 4 at Nonantum Road in Boston and WASM 3 at Mystic Valley Parkway in Medford to increase the supply from the Northern Low Service System and reduce the need to pump non-potable water out of the Spot Pond Reservoir in an emergency. The new larger pressure reducing valves at Nonantum Road and Mystic Valley Parkway will be designed to be controlled remotely through SCADA. The Northern Low Service pipeline would operate at increased grade lines to supply additional flow to the Spot Pond Pumping Station and Storage Facility and the Gillis Pumping Station in an emergency condition with the tunnel system out of service.
The contract will demolish the existing Nonantum Road and Mystic Valley Parkway PRV vault structures, including four 24-inch PRVs and appurtenances, and construct new larger cast-in-place vaults. At Mystic Valley Parkway, two 42-inch PRVs and at Nonantum Road two 30-inch PRVs, isolation valves, piping, and other appurtenances will be installed. Additionally, a new master meter will be constructed at the Mystic Valley Parkway pressure reducing valves and the existing master meter located near the Nonantum Road Pressure reducing valves will be upgraded to accommodate the increased flow.
Work will be sequential, starting at the Mystic Valley Parkway PRV Vault, followed by the Nonantum Road PRV vault. The construction duration is 24 months.
