ROCKINGHAM, Vt. – On Tuesday, Oct. 4, the Rockingham Selectboard heard a presentation from Watershed Consulting Associates (WCA) Principal Hydrologist Andres Torizzo on proposed mitigation solutions for drainage at Imtec Lane and Spencer Drive.
Municipal Manager Scott Pickup notified the board that the town is finalizing an Environmental Mitigation Grant application with the Vermont Agency of Transportation (VTrans). Pickup said that this started with the Emergency Watershed Protection (EWP) project, looking at the damage around Sonnax from July storms, and led to a larger field investigation on water sources causing rapid erosion. Pickup said that the challenges were managing the sources impacting Spencer Drive and the Railroad.
Torizzo highlighted areas where substantial erosion had occurred, including the northern gully near Chroma and the southern gully on Spencer. WCA came up with design solutions to mitigate the stormwater flows to both gullies, involving underground chamber systems called StormTech systems. He said, once buried, it “functions like a leach field,” with all mitigation underground and the site is restored.
At Imtec, a combination surface infiltration basin and subsurface chamber system would be used. Torizzo said that Spencer Drive was more complicated, due to the amount of runoff and the rapid erosion that that location has experienced. The project would add three chamber systems and four drywells as open catch basins, which he said will “substantially reduce the amount of erosion and sedimentation occurring in the gully.”
Board member Bonnie North asked about the life span of this system. Torizzo said the State uses a 30 year life span, but said that the systems can last much longer if maintained. Maintenance required the use of a Vactor truck, he said, and was generally performed annually, with frequency depending on the amount of sediment.
Chair Peter Golec asked if there were brooks or streams adding to the run-off. Torizzo said that the run-off primarily came from rooftops, paved surfaces, and most notably from Route 5.
Torizzo shared the preliminary overall cost of $1.325 million, which included stabilization of rock lined gullies on the south, originally designed to mitigate a 50 year storm, and a rock lined pool on the north end designed to mitigate a 100 year storm. He said that with federal funding of $1.06 million, the municipal match would be 20%, or $265,000. Torizzo explained that the grant required a letter of support from the town, acknowledging the source of local match and commitment for future financial responsibility.
Vice-Chair Susan Hammond asked if the town could produce the crushed rock and gravel. Pickup said the town could look into that, depending on quantities and size required. The board approved the motion unanimously, supporting the mitigation grant.
Pickup explained that the $10,000 request for supplemental funding was to deal with washouts while they waited on the VTrans application for the larger scale project.
Photographs were submitted showing a 15-foot drop close to the road caused by heavy rains from the July 2022 storm, and a silt-filled culvert under the railroad tracks.
Development Director Gary Fox said the railroad had emptied the culvert “four times in the past month.”
Pickup said that this was not a solution, but would give immediate relief to “potentially avoid having another 800-yard washout.”
The board unanimously approved the request for $10,000 from the general fund balance to purchase stone and rip rap.
The selectboard meetings are on the first and third Tuesdays at 6 p.m. in the Lower Theater of the Bellows Falls Opera House.