BENNINGTON โ Developer Bill Scullyโs hydroelectric facility on the Walloomsac River has been offline since May, after an underwater drilling operation apparently churned up silt behind the water intake area โ threatening the plantโs generating equipment should it be restarted.
Bennington officials said the problem developed as crews with PDD Contracting LLC of East Greenbush, N.Y., were using a high-pressure air process to drill horizontally beneath the riverbed upstream from the former Vermont Tissue Paper mill dam off Route 67A, which Scully owns.
The planned drilling path ran under the Paper Mill Bridge, which crosses from Route 67A to Murphy Road just upstream from the dam and hydro site.
Water line project
Town Manager Stuart Hurd said that the drilling in early May was part of ongoing water line extension work in the town and North Bennington Village. That project is designed to provide clean drinking water to properties around the former ChemFab Corp. factory on Route 67A with PFOA (perfluorooctanoic acid) contamination in wells.
Hurd said the drillers, a subcontractor to water line contractor Schultz Construction Inc., of Ballston Spa, N.Y., were facilitating the creation of a loop in the extended water system that would cross the Walloomsac to Murphy Road. Such loops are desired, he said, to reduce dead-ends in the water system, which could lead to water pressure issues for some sections.
Scully and Hurd said there have been attempts to mediate an agreement among the various parties, including the town, Scully, the contractors, project designers MSK Engineering and Design, the insurers, and the state Agency of Natural Resources.
Thus far, Scully said Wednesday, the central issue as far as he is concerned โ who will pay to remove the built-up silt behind his hydro facility so he can restart without damaging the equipment โ remains unresolved.
โThe town of Bennington has been a great friend to all our endeavors in the past,โ he said, โso we are confident that we will be made whole as we have been assured. Were it not for their initial understanding of the need to shut the plant down during drilling, the turbines may have been destroyed by the blown-out material.โ
He added that an โopen-ended agreementโ was put in place prior to the drilling to compensate him during the shutdown โ which was expected to be for only a short period.
โWe are exploring our options,โ Scully said of possible litigation. โIt would be our option of last resort, but it is certainly looking like we have few alternatives. Our business depends on it.”
Scully purchased the historic mill property in 2009 and eventually received state and federal permits, redesigned and restored the hydropower plant there, launching the 360-kilowatt hydro facility in 2016. He also owns a three-quarter mile water impoundment area extending upstream from the dam.
Liability considerations
Hurd said of possible costs and liabilities: โThe determination of any payments will be based on a determination of liability and damages. I wouldnโt want to predict this outcome at this stage.โ
Assistant Town Manager and Planning Director Dan Monks said a new location to drill under the Walloomsac riverbed has been located and that work is set to begin soon. He said the location is downstream from the hydro facility.
Scully said he was told that the state will want to approve any plan to remove the sediment behind the intake area, in part because it is likely to contain PCBs (polychlorinated biphenyl), dioxin, lead or other contaminants similar to material Scully removed prior to restoring the hydro facility.
Another consideration for the state, and likely for the Federal Energy Regulatory Commission, which licenses hydro facilities, and federal and state and wildlife officials, is the possible effect on fish habitat downstream from the dam.
โThe state has said it wants it [the silt] removed,โ Scully said, โbut nobody has agreed how this will be paid for.โ
He added, โEverybody agrees the breach happened, that it wasnโt Carbon Zeroโs [his hydro project] fault, and that the problem should be fixed.โ
According to Jeff Crocker, of the state Department of Environmental Conservationโs Watershed Management Division, โThe blowout from drilling under the river for the waterline modelized upstream sediment that deposited in the intake area of the hydro project. To restart the project the state wants to see a plan that assesses the volume of sediment that will likely be mobilized by the project operations and proposes appropriate measures to be taken prevent sediment from mobilizing.โ
Crocker added, โAt this point it is likely some portion of the sediment will need to be removed and given the history of contamination at the site, testing the sediment will need to be done before removal to determine how to dispose of the material.โ
Another concern, Crocker said in an email, is that โthe state canโt authorize a discharge of sediment into state waters,โ such as below the dam past the hydro intake area, especially considering the history of contamination previously found behind the dam.
Bubbling ‘chocolate’ water
Scully said the horizontal drilling that began May 1 took place about 30 feet upstream from the mill dam and close to the covered bridge, where the river is about 100 feet wide.
According to a copy of engineering plans he has, the drilling line was to extend under the covered bridge from the Route 67A corridor to Murphy Road on the opposite bank. From there it would meet other sections of new water line.
Scully said he understands that the first sign of a problem was a surge of water coming back out of the drilling hole. A day later, he said, there were bubbles of air under the covered bridge surging up from the river bed and churning the water and sediment.
Sometime afterward, he said, there apparently was a โviolent eruptionโ of air and churning water that turned the river a chocolate color.
Scully said he measured 9.5 feet of silt at one end of the dam and that the material extends at varying depths across the 80-foot dam.
The hydro project was unique, Scully said, in that it both cleaned up toxic sediment behind the old mill dam and created renewable energy. But now sediment has filled back in behind the structure and could have the same PCBs, dioxin or other contaminates he found and removed in restoring the facility.
Scullyโs sediment removal project involved setting up a temporary cofferdam to create a dry space behind the mill dam so that material could be removed.
The sediment and other factors could be of concern to FERC as the hydro facility licensing authority, as well as to the ANR, he said, and could prompt additional federal or state reviews.
The water-line extension work is being funded by Saint-Gobain Performance Plastics, the last owner of the ChemFab operation in Bennington, before that operation was moved to New Hampshire in 2002. State environmental officials have identified Saint-Gobain as the responsible party for providing clean drinking water to the affected properties.
