PITTSFIELD, Mass. — Engineers have gotten approval to try a new way to alleviate environmental concerns related to a maintenance project at the Cleveland Reservoir, the main source of the city's drinking water.
The project plan is to clean out the diversion pipes in both Cady and Windsor Brooks, which feed into the reservoir. The two inlets had been collecting sediment for decades, and that has then been flowing into the reservoir. In 2012 the project to clean out the aqueduct system was proposed. But, some concerns were raised about the creation of an access road, which would take away wetlands habitats for animals, and ongoing dredging of the river.
Doug Gove from the engineering firm Aecom has been working on the project and the Hinsdale Conservation Commission - the reservoir is in Hinsdale - to find ways to mitigate the impacts.
Gove had determined that there really wasn't much room near the project to replace the lost wetlands. Instead, the firm has come up with a plan to send 10 percent of the water coming into the reservoir down the two brooks. The additional plow is eyed to improve the downstream ecosystem and reduce the amount of ongoing maintenance in the future.
"The city thought it was a win-win situation where the city could release water downstream without too much of an impact on their water supply," Gove told the Berkshire Regional Planning Commission's Environmental Review Committee on Thursday.
Gove said the engineers spent a lot of time looking at other sites near Ashmere Lake and at some culvert crossings off site to rebuild the wetlands lost but nothing there seemed fitting. The area around the project and the reservoir has a lot of upland wooded areas so that wouldn't work and another option along Cady Brook would have required the removal of trees.
Diverting more water downstream is a new method the state has been trying out and in this case, Gove said the reservoir has enough water to do so without compromising the city's water supply. The state Department of Environmental Protection and Hinsdale Conservation Commission have both approved the efforts. And, BRPC has opted to support the concept as well.
The structure is designed to "self-regulate" the water flow it sends downstream. But the city does have the option to suspend the release in times like this past year when there was a severe drought.
The reservoir is filled every spring and in the winter, the city lowers it. Gove said even during the drought the reservoir was still at 8 feet.
"It will self-regulate. It will pretty much be a natural set up. It is maintenance free," Gove said.
Essentially, the system is designed for 90 percent to flow into the diversion system for the reservoir and once that pipe hits capacity, the rest will be sent downstream.
"Right now there is no flow and there is pooling in certain areas," Gove said.
Gove estimates that the project will double the flow in Cady Brook and create more than an 83 percent increase in Windsor. That may sound like a lot but in reality, it isn't even enough to support fish. The flow is more of a trickle than a rushing and will help support amphibian and reptile habitats. Currently, water flow below the reservoir is very limited.
"There will be more moisture but there won't be aquatic fisheries," said BRPC Planner Lauren Gaherty.
"It is a fairly new mitigation technique that DEP seems to be coming around to... This is something DEP is turning to as something different than trying to replicate wetlands."
The additional flow will help the streams and wetlands by bringing added oxygen and nutrients downstream, Gove said, improving the ecological conditions.
"We tried to create a balance that would be beneficial to both the city and downstream habitat," Gove said.
Only about 1,600 square feet of wetlands is being taken to build the access road. But that could naturally create more wetlands because of stormwater runoff, Gove added. The project is planned to reuse the material taken from the wetlands area.
"One thing that was a change from the original was that we came up with a game plan as part of removing the sentiment, we are going to free up the low-level outlets," Gove added, saying by opening those up more sediment will flow downstream instead of being caught up in the brook. "It will reduce the frequency of having to go in and do maintenance dredging."
Gove doesn't know how often the brooks will have the be dredged for maintenance because the current build up has been in the making for decades - so it isn't clear how quickly the sediment will pile up again.
BRPC is Okay with giving it a try but it wants to follow up information to see if the downstream flow actually makes a difference to the ecosystem.
"I'm willing to support that because I think getting that information out so that other projects could use it," responded Pittsfield Commissioner of Public Services and Utilities David Turocy.
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