WINDHAM — Drivers traveling Interstate 93 in Windham the last few days likely have noticed a big change — no trees in the median between the two weigh stations near Exit 3.
The area being clear cut will soon see construction of a handful of water quality basins, according to Peter Stamnas, the I-93 project manager for the New Hampshire Department of Transportation.
“It’s not what we typically do, but we have to meet our water quality commitments for the project,” Stamnas said yesterday. “It’s extremely complicated and extremely expensive.”
But it’s also necessary. The basins will first serve a temporary purpose for construction stormwater management.
Dirty water runoff from the construction site is a concern, for the state and for nearby residents worried about impacts on nearby Cobbett’s Pond and other water bodies in the area.
Earlier this month, following two big rainstorms, the Cobbett’s Pond Improvement Association and Canobie Lake Protective Association appealed to the state to do a better job of preventing turbid water running from the work site to the lakes.
When about 41/2 inches of rain fell over the last weekend in March, the DOT’s stormwater protection system was overwhelmed.
Residents say it wasn’t the first time, but they want it to be the last.
After that incident, Jay Levine, DOT coordinating supervisor for the I-93 widening project, acknowledged the problem, but also noted the state is spending an estimated $2 million to $3 million to manage runoff and control erosion in Windham alone.
The water quality basins should help, Stamnas said.
Their construction is the last piece of the project at Exit 3, he said, and will complete the work in the northbound mainline near the weigh stations.
The area being clear cut will be filled with excavations — some resembling small ponds, others big holes in the ground — to store and treat water that comes off the construction site, he said.