A Strong and Safe Water System
JOHN J. CARROLL WATER TREATMENT PLANT
The John J. Carroll Water Treatment Plant treats drinking water for MWRA communities from Northborough eastwards. The plant, located in Marlborough, uses ozone gas, a powerful disinfectant, to treat up to 270 million gallons of water daily (up to 405 on a peak day). Ozone gas bubbled up through the incoming water provides better disinfection without the byproducts of chlorine.
METROWEST WATER SUPPLY TUNNEL - STARTED UP IN
This 17.6-mile long deep rock tunnel from Marlborough to Weston is the backbone of MWRA's new water system. It connects the new Carroll Water Treatment Plant and aqueducts from the Wachusset and Quabbin Reservoirs to the Metro Boston and Metro West areas.
The MetroWest Water Supply Tunnel is 14 feet in diameter, bored into solid bedrock and lined with concrete. It greatly enhances the security, capacity and reliability of MWRA's entire water transmission system.
The new tunnel began operating in November 2003. Until then, MWRA relied on a single 1940's-era surface aqueduct, the Hultman Aqueduct, to serve all of Metro Boston. With its leaks and aging valves, the Hultman needed to be taken off-line for major repairs. Before the MetroWest Tunnel, failure of the Hultman could have caused nearly complete interruption of Boston's water supply. This would have been a disaster for the region's public health, safety and economy.
The $665 million construction project started in 1996. It was completed on schedule and under its $700 million budget.
COVERED WATER STORAGE TANKS - NORUMBEGA TANK TOPPED OFF IN MAY 2004
At 115 million gallons, the Norumbega Covered Storage Tank in Weston, along the Mass. Turnpike is the largest in the country. The tank's three compartments are filled through a shaft in peak demand periods. Water in the 26-foot deep tanks is routed around a series of baffles. It only stays in the tank for 12 hours on average.
Other covered storage tanks include Loring Road in Weston, Nash Hill in Ludlow, Fells in Stoneham, Blue Hills in Quincy and one at the Carroll Water Treatment Plant. An addtional tank is Stoneham region is underway.
WATER PIPELINE REHABILITATION - ONGOING
MWRA has a 275-mile long network of large water pipelines to deliver water from tunnel systems to community meters. A large proportion of these pipes are unlined cast-iron mains from the late 1800s and early 1900s. MWRA has a systematic 20-year program to replace or rehabilitate these mains.
Dozens of pipeline projects have been completed, many in dense urban areas or on busy roadways. Rehabilitated pipelines greatly improve drinking water quality, system reliability and water pressure.
MWRA's Local Pipeline Assistance Program provides $25 million per year in zero-interest financing to communities for their own pipeline rehabilitation projects. MWRA communities in the Metro Boston area own over 5,000 miles of smaller pipelines.
WATERSHED PROTECTION - ONGOING
Excellent quality water in the Quabbin and Wachusett Reservoirs is the greatest asset of the MWRA water system and their protection and management are the foundations. Over 75 percent of the combined Quabbin-Ware-Wachusett watershed system, covering 401 square miles, is either protected open space or regulated through the Watershed Protection Act.
Key Elements Watershed Protection:
Updated February 2, 2012