MWRA WATER MAIN BREAK

Impacts to the Charles River from the May 2010 MWRA water main break

Photo by Julie Wood

UPDATE- October 17: Vacuum dredging has begun to remove the massive volume of sediment that was washed into the river when the MWRA water main broke causing drinking water to pour into the Charles for approximately 12 hours, nearly doubling the river’s flow.  It was estimated that the gushing water carried between 300 and 500 cubic feet of dirt and debris into the river, completely collapsing the bank.  Dredging will take place on both sides of the river in the vicinity of the break.  CRWA has been and continues to work very closely with MWRA and local conservation commissions on dredging, bank re-stabilization and other issues related to the cleanup from this accident.  Additionally, CRWA will be in the field this week as the dredging continues to observe the process.

UPDATE - May 27: MWRA contractors are shoring up the large water main beside the Charles River in Weston as they prepare to dig up the area in search of the still-missing piece of the broken pipe coupling (also called a pipe collar).  Finding the coupling is critical so MWRA can understand the cause of the water main break at the beginning of this month, and determine whether other locations with similar coupling devices may be at risk.  Bank restoration plans are being finalized under an emergency Wetlands Protection Act Order overseen by the Weston Conservation Commission.  Meanwhile, temporary bank stabilization efforts have held up well to date.  MWRA will begin phase II of their clean-up work (potentially removing more sediments from the river) once this phase is complete.

Overview

The Massachusetts Water Resources Authority's (MWRA) water connector pipe that began leaking and then broke completely on Saturday, May 1 resulted in over 8 million gallons an hour of water pouring into the Charles River.  For a time, the flow of the river at the Waltham gage, downstream of the break, doubled from approximately 350 cubic feet per second (cfs) to approximately 700 cfs.  The pipe connection broke 20 feet below ground near Recreation Road, and the gushing water carried an estimated 400 cubic yards of soil and sediment directly into the river. 

The MWRA did dredging work in the Charles at the site of the water main break for several days, completing their work on on May 10.  Preliminary estimates are that 300 - 500 cubic yards of sediment have been removed from the river.  A second set of silt curtains were placed around the dredge area as the primary curtains began to release fine silt into the river.  There is still no sign of the missing collar segment that broke away, causing the water main failure.

The week after the break, CRWA monitored the Charles in the vicinity of the dredging as well as a short distance downstream in order to determine sediment levels in the river. If the concentration of Total Suspended Solids (TSS) in the river exceeds 15 mg/l, the river herring migration could be impacted. Fortunately, CRWA's results showed that TSS levels were well below that, with the highest concentration being 6.5 mg/l.

The area where the water main break occurred has been stabilized with crushed stone and hay bales.  MWRA is working with the Weston Conservation Commission and MassDEP to develop a bank restoration plan that will include regrading the bank and replanting with native wetland species.

The timing and details of the next phase of the project – determining the extent of sediment deposition in the river outside of the immediate area of the break, and planning any necessary mitigation – have not yet been finalized.

River herring, which have entered the Charles on the annual migration upstream to spawn, have not yet been spotted above Watertown Dam and so are not likely to be impacted by this stage of restoration work. 

Update from May 17: MWRA has been operating under an emergency order from the Massachusetts Department of Environmental Protection (MassDEP) and under the direct supervision of the Weston Conservation Commission as they work to restore the river and bank.  CRWA has continued to monitor the river to help identify potential impacts.  MWRA has completed dredging sediments out of the river in the area immediately adjacent to the break, where between 300 and 500 cubic feet of dirt and debris were washed into the river and the bank collapsed.  MWRA is finalizing bank restoration and planting plans, and will then begin downstream sediment sampling to determine the extent of any additional impacts. 

Background

CRWA staff and volunteers have been monitoring the river, tracking the plume of fine sediment that has been moving down the river since the break.  The river ecosystem has been extremely stressed during the past month, first by March's huge floods, then by the Department of Conservation and Recreation's rapid drawdown of the river to allow repairs to the Moody Street dam, and now by the flood of drinking water and sediments from this water pipe break.

Additional Information

WBZ-TV news clip featuring an interview with CRWA's Julie Wood discussing how herring may be harmed by sediment, from May 6.

WCVB-TV interview with CRWA's Kate Bowditch discussing impacts to the river of the water main break, from May 4.

A 'catastrophic' rupture hits region's water system, Boston Globe, May 2.

Updated May 19, 2010