I-93 construction still causing sediment problem for Cobbetts Pond

Salem Editor — Wed, 22 Apr 2009 18:47:00 GMT

BY DERRICK PERKINS

State officials and a local group are pulling out all the stops to ensure no further environmental damage is done to Cobbetts Pond after a second wave of sediment washed into the water.

Reported by a homeowner on April 3, the sediment plume in Heron’s Cove marks the second release of fine silt into the 345- acre pond tied to the ongoing construction work near Exit 3 of I-93. During a two-day period in last December, nearly 4 inches of rain fell on the site, overwhelming existing erosion control methods and causing the release of a roughly 1,000-foot plume of sediment into the pond.

That incident led to the start of weekly meetings between officials with the New Hampshire Department of Transportation, representatives of the Cobbetts Pond Improvement Association and the contractor handling the work, Middlesex Corp.

While disappointed by the latest sediment release, CPIA spokesman Derek Monson said the state has made serious efforts to prevent silt from flowing from the construction site into the pond.

“They’re trying. They’ve made great progress since the December 12 incident, but it’s a big site. It’s a lot of open land there,” Monson said. “Unfortunately, something fell through the cracks. There is always room for improvements. It’s disappointing, but they have come a ways since the first time.”

Mark Hammerlein of the state DOT said the sediment released in the latest incident likely came from three different sources near the Exit 3 construction site, including an unpaved parking lot used by project workers.

Hammerlein said a single catch basin – not yet cleaned out from winter – likely caused the sediment deposit after collecting the silt-filled runoff from the parking lot and from the west end of the construction site and washing it into the Cove Brook, which feeds the pond.

A nearby private construction project may have also factored into the sediment release, he said.

In response, Middlesex Corp. now plans to pave the parking lot and separate the everyday in-and-out traffic from the larger construction equipment that is used to haul the sediment. The state DOT has also arranged for a cleaning crew to come in on April 20 and begin clearing out the catch basins around the pond.

“We take this pretty seriously. We put a lot of time and effort into erosion control,” Hammerlein said.

According to Monson, the CPIA has filed a formal complaint with the state, but has not taken any legal action in relation to the latest incident. He said the state’s response following the initial release of sediment was great and had worked to protect those areas of the pond affected. The CPIA plans to continue cooperating with state officials and Middlesex Corp. to prevent further erosion.

Bill Cass, a project manager with the DOT, welcomed their efforts and encouraged residents near the project to report any problems that might arise stemming from the construction work.

“We want to know what’s going on, tell us ... A lot of time it doesn’t come back to the people on site for some time, so we can’t take immediate action,” he said. “There are a lot of things going on to manage the erosion control and it is complicated. Any input, any ideas that can help, we’re always welcoming them.”

Windham News : construction

I-93 construction still causing sediment problem for Cobbetts Pond