Massachusetts Water Resources Authority
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The Massachusetts Water Resources Authority (MWRA) is a public authority in the Commonwealth of Massachusetts that provides wholesale drinking water and sewage services to certain municipalities and industrial users in the state, primarily in the Boston area.
The authority receives water from the Quabbin and Wachusett Reservoirs and the Ware River in central and western Massachusetts. It also operates an effluent tunnel in Boston Harbor for treated sewage as well as a treatment center on Deer Island at the mouth of the harbor, among other properties.
The MWRA was created in 1986 and assumed sewage and wastewater treatment functions from the former MDC (Metropolitan District Commission), now the DCR (Department of Conservation and Recreation), which still maintains the watershed lands.
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[edit] MWRA water system overview
The Massachusetts Water Resources Authority and the Massachusetts Department of Conservation and Recreation (DCR) own and operate the collection, treatment, distribution, and storage facilities that supply drinking water to some forty municipalities in the metropolitan Boston area. This water system design was based upon the purchase and subsequent protection of an entire watershed. This design assures that the water remains as pristine as possible. However, modern regulations require that all supplies of drinking water be chemically treated regardless of the source.[1] Additions to the MWRA water system throughout its history have resulted in redundancies that allow major sections of the water system to be shut down for repair or maintenance.
[edit] Water flow
Water flows from the MWRA's main storage facility, the Quabbin Reservoir in central Massachusetts, through the Quabbin Aqueduct to the Wachusett Reservoir in and around Boylston and Clinton.[2] Tributary rivers and streams comprising the Wachusett watershed, a 108 square mile (280 square kilometer) drainage basin, also feed the Wachusett Reservoir. At the eastern end of the Wachusett Reservoir, water enters the Cosgrove Tunnel at the Cosgrove Intake. The Cosgrove Tunnel feeds both the MetroWest Water Supply Tunnel (MWWST) and the Hultman Aqueduct. The MWWST starts from the Carroll Water Treatment Plant in Marlborough. The Hultman branches off at Framingham in two directions. The smaller branch, the Weston Aqueduct, empties into the Weston Reservoir in Weston. The main branch continues to the Norumbega Reservoir, also located in Weston.[2]
[edit] Redundancy
In an emergency, water can be treated with sodium hypochlorite at any point in the system by deploying Mobile Disinfection Units. Since completion of the covered storage reservoirs in Ludlow, Weston and Stoneham, all of the open distribution reservoirs (Spot Pond, High Fells, Chestnut Hill, Waban, Norumbega and Weston) and backup storage reservoirs (Sudbury and the three reservoirs of the Framingham system) and the Sudbury and Wachusett Aqueducts consititute a backup network for emergency use.
[edit] John J. Carroll water treatment plant
Located at the town lines of Marlborough, Northborough, and Southborough, Massachusetts, this facility replaces the one used previously only for pH control.[3] It comprises four ozone generators with diffusers and five concrete contact chambers with a volume of 11.3 million gallons (42.7 million liters). The plant has a capacity of 275 million gallons (1.04 billion liters) per day, on an average day or 405 million gallons (1.53 billion liters) per day, at peak level. It cost US$340 million.[4]
After being treated at the Carroll Treatment Plant, water goes through the Metro West Water Supply Tunnel to covered storage tanks in Weston and Stoneham. An additional tank is scheduled for construction at the Blue Hills in Quincy and there are two tanks in Ludlow that feeds the communities of Chicopee, Wilbraham and South Hadley (Fire District No. 2).
[edit] Electrical generation
The system includes three hydropower stations, with a total capacity of 8 MW.[5] Water released to the Swift River flows through the turbines at Winsor Station below the Winsor Dam. Water transferred from Quabbin to Wachusett can pass either through the turbines at Oakdale or through bypass pipes when flow requirements exceed turbine ratings. Water released from Wachusett into the Cosgrove Tunnel passes through the Cosgrove turbines.[2][4]
MWRA power generation
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The Quabbin Aqueduct connects the two reservoirs, and relies upon gravity to accommodate the three separate operational needs. First, diversion of water from the Ware River into the Quabbin Reservoir uses this aqueduct. Second, water transfer from the Quabbin Reservoir to the Wachusett Reservoir, through a hydropower station or a bypass pipe, uses it as well. The bypass valves are non-regulating valves, and when opened, only the head in the Quabbin Reservoir and the physical characteristics of the aqueduct govern the flow. Because the turbines are flow limited, the bypass mechanism permits transfer rates nearly twice as high as are possible through the turbines. Operationally, the single aqueduct fulfills three purposes, but only one operational mode is possible at a given time.[6]
[edit] MWRA references
- ^ Safe Drinking Water Act. Retrieved on December 1, 2006.
- ^ a b c MWRA water system. Retrieved on December 1, 2006.
- ^ John J. Carroll water treatment plant. Retrieved on December 1, 2006.
- ^ a b
- ^ Electrical power generating plants. Retrieved on December 7, 2006.
- ^ Water system configuration. Retrieved on December 1, 2006.
[edit] External links
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