By JOSEPH FITZGERALD

NORTH SMITHFIELD — The town is looking to undertake a quarter-million dollar project to prevent pollution to the Branch River caused by stormwater runoff.

Called the Branch Village stormwater retrofit project, the town wants to construct a man-made wetland that will divert untreated runoff from an existing 30-inch pipe that currently discharges directly into the river.
A constructed wetland is a man-made marsh or swamp that uses water-purifying plants as biofilters to remove sediments and pollutants such as heavy metals from the water.
Town Planner Michael Phillips said the proposed $234,200 project is an opportunity for the town to mitigate a major source of pollution to the Branch River, which is the largest tributary to the Blackstone River.
See POLLUTION, Page A-2
“We see the restoration of this as part of a larger local planning effort to revitalize the historic Branch Village, leverage significant environmental improvements and increase awareness of this valuable natural resource,” he said. “As such, the town views this project as a construction project and will use the funds to build improvements along the piped system to an outdated outfall.”
The town has filed a water quality improvement grant application with the Department of Environmental Management seeking $174,810 to be used in conjunction with $59,390 the town already has earmarked for the project, which is expected to take 24 months to complete. Assisting the town in the grant proposal is the Horsley Witten Group, the consultant working with the Branch Village Task Force, and Smed Blair, owner of the Branch River Industrial Park property.
According to Phillips, the project entails retrofitting an existing private stormwater system with a forested constructed wetland, which would achieve significant water quality improvements by addressing stormwater pollutants from an outfall to the
Branch River. The existing 30-inch pipe currently discharges directly to the river with no treatment. This pipe carries runoff from a dense residential neighborhood and a portion of an industrial park - a drainage area of approximately 18 acres.
By diverting stormwater from small, frequent storms (first inch of runoff) to a constructed stormwater treatment wetland facility, Phillips said, the water quality will be improved via the settling of solids, uptake of nutrients by vegetation, ultraviolet breakdown of bacteria, and increased oxygen due to aeration.
The additional benefits from the project include the creation of both wildlife habitat and a recreational trail through the system that will allow public access to the river as well as raising the neighborhood’s awareness of stormwater runoff.
Constructed wetlands are excavated basins with irregular perimeters and undulating bottom contours into which wetland vegetation is purposely placed to enhance pollutant removal from stormwater runoff. The system is designed to maximize the removal of pollutants from stormwater runoff via several mechanisms - microbial breakdown of pollutants, plant uptake, retention, settling and adsorption.
Here’s how it will work: The constructed wetland system will divert stormwater with a diversion manhole from the existing 30-inch stormwater pipe on the site off Great Road. After the runoff has been treated, stormwater that has not evaporated or been utilized by the wetland vegetation, will flow over a level spreader spillway.
John Flaherty, chairman of the Branch Village Task Force, which is working to revitalize the 300-acres Branch Village district along Great Road near Route 146, said if the grant is awarded, it will make a “significant and positive difference” in how storm water is handled and treated in the village and how it impacts to the Branch River.