The impact of high-elevation wind turbines on waterways should be carefully watched to reduce the chance of increased flooding downstream. That was the advice from a water resource engineer to a group of Grafton residents hoping to prevent an industrial wind project in their town.
The Grafton forum was the third event in a series held by local wind opponents and Vermonters for a Clean Environment, a statewide nonprofit group. The local opposition group formed after the Spanish energy giant Iberdrola Renewables built three wind test towers in Grafton and Weston.
No project has yet been proposed in the southern Vermont towns. But both towns have a history of flooding. And some citizens worry that an industrial wind project at the headwaters of several streams would make the situation worse.
Hydrologist Geoff Goll says those concerns are well founded.
"When headwaters are compromised, flooding issues that already exist can become exacerbated," Goll says. "And once the headwaters are developed, it’s very difficult to remediate those areas."
Goll is vice president of Princeton Hydro of New Jersey. The firm was hired by an appellant to study the site on Lowell Mountain where 21 ridge top turbines are now running. He says high-elevation headwaters are the source of clean, cold groundwater that’s absorbed in the forest and uneven mountaintop terrain.
He says the construction of multiple 450-foot turbines renders large areas impervious and prone to runoff in storms.
"You first need turbine pads," Goll explains. "That’s where the turbines are going to be located. These are about an acre and a half in size, two acres. They have to be flat. So you have to excavate into the steep hillside to make a flat area." At the Lowell site, Goll says workers had to cut 45 feet down into the bedrock to build those flat areas. And getting towers and equipment to the ridge tops required building roads.
"The roads have to be at least 30 feet wide," Goll says. "And they can expand to about a one-hundred-foot width of impact because you have to build the face of the slope up. They have to be at a slope that can be managed by a tractor trailer truck."
Goll says he isn’t opposed to big wind installations. But he says industrial activity on ridge tops involves new challenges and new technologies that should be carefully assessed before and after projects are built.
"The key to assuring that these projects work is baseline monitoring,” he says. That means going out before the project starts, collecting the data and getting the info you need, so that if there are impacts later on, you can find out what those impacts are."
But a spokeswoman for Green Mountain Power says its wind project in Lowell meets water quality standards. Dorothy Schnure says the state regularly inspects the storm water systems.
"And they have said they’re working very well," says Schnure. "And we have done some baseline testing of waters in the area and there’s no change, so we’ve been very successful in the way we’ve managed the water at Kingdom County Wind."
Schnure says at some sites the technology being used to prevent erosion and redirect run-off has actually improved water quality.
