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.
Project Updates
June 13, 2023
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Working on grating within the vault
W16 Venturi Meter Chamber installation
New Venturi Site Restoration
March 29, 2023
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W16 - Installing supports for top slab
Roof slab decking in place, installing rebar
W16 - installing new steel pipe west of the vault
W14 - Cabinet installation
March 2, 2023
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Recently Completed:
- Pressure tested valves and piping at W14
- Continued rebar, forms and placing concrete at W16
Upcoming:
- Complete fill at W14 for visual inspection of closure piece and complete backfill
- Continue concrete work at new W16 vault
W16 - Placing concrete for the east wall of the PRV vault
W16 east wall forms removed
W14 - Interior view of cement mortar lining
W14 - Ductbank and equipment and concrete placement
February 2, 2023
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Recently Completed:
- Installed valves and started backfilling at W14
- Installed rebar and started placing concrete at W16
Upcoming:
- Conduct pressure test of pipe and valves at W14
- Continue concrete work at new W16 vault
W14 Temporary 48” Blind Flange installed at Station 64+54.5
W14 8’” Bypass at Station 64+29.2
W14 Concrete Placed for the Thrust Block at Station 64+51.5
W14 Backfilling and installing cathodic protection
Filling for pressure test at W14
W16 Placing Concrete for the North Wall of the PRV Vault
W16 steel work under the tarp
December 28, 2022
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Recently Completed:
- Completed W14 pipe and PRV installation
- Completed ductbanks at W14
- Started Demo at W16
Upcoming:
- Complete butterfly valve installation at W14
- Continue with new vault at W16
W16 Construction forms for base slab
Steel pipe and PRVs delivered
W16 Placing rebar for the North and South walls of the PRV Vault
W14 ductwork for power and cabinet pedestal set up
Butterfly valve installation at W14
November 3, 2022
Applying tape at welded joints at W14
W16 Demo of existing PRV vault
Screening was pulled back to improve sightlines for vehicles exiting parking lot.
November 3, 2022
Construction updates will be posted here.
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