You may hear press accounts about the discovery of PCBs (polychlorinated biphenyls) at the Wachusett Dam in Clinton.

When the Massachusetts Water Resources Authority was preparing to do some construction work at the dam spillway, the caulking at the top of the dam was tested and discovered to contain PCBs.

Additional water samples have been collected from the reservoir and no PCBs were detected.  It is important to note that PCBs have never been detected in samples from the Wachusett Reservoir.

Subsequent review of the dam construction indicated that caulking was used to seal joints in concrete slabs across the top of the entire dam during the 1950s. PCB compounds were often used in construction prior to 1977, when they were banned.

MWRA has collected samples regularly since they were first required in 1993. In view of the discovery of PCBs at the dam, we sampled the water in the immediate area of the dam and no PCBs were detected in the water. 

Soil samples from the base of the downstream side of the dam were found to contain reportable levels of PCBs, which triggered notification to the Department of Environmental Protection in accordance with the Massachusetts Contingency Plan.

MWRA has begun preparing an expedited remediation plan, which must be approved by the U.S. Environmental Protection Agency, describing removal and methods to contain the material during removal. 

Again, no PCBs have been detected in the water MWRA delivers.

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