North Adams Con Comm Approves Stormwater Project in Blackinton
NORTH ADAMS, Mass. — A project to divert stormwater from Wood Street to a catch basin on Ashton Avenue was approved by the Conservation Commission on Wednesday.
The notice of intent was submitted by Waterfield Design Group of Winchester on behalf of city of North Adams. Jacob Murray, engineer with Waterfield, presented the plan to the commission at the public hearing.
Of interest to the commission, is a wetland and flood plain on the west side of Ashton Avenue and a mountain channel on Wood street.
"The situation is that currently there is a 12-inch and 15-inch to a 24 to a 30-inch drainage pipe that collects a mountain channel coming down Wood Street, and that directs it to some clogged 54-inch culverts that are underneath Ashton Avenue," Murray said. "These pipes are undersized for carrying the capacity for significant storm events, potentially, like one that is going on right now (heavy rain from Hurricane Ida). ...
"What happens is that in those events, this overflow comes down like a river through Wood Street, hits the curb here, and ends up flooding out both the old [Blackinton] mill building as well as the McClain property here and the garage, heading down into the tail race before it hits Ashton Ave."
The plan is to replace the existing pipes with a 60-inch pipe down Wood Street and then mostly along the same track, until it crosses under Massachusetts Avenue to the south before the intersection with Ashton to avoid a 24-inch water line.
"What will happen here is that instead of having this flooding river during significant events, it'll all be able to be captured in the pipe and then outlet to Ashton Avenue," Murray said, adding that to make the improvements, there will also have to be a retaining at the outlet and a riprap spillway that will disturbe about 150 square feet of wetlands.
That area will be replicated in the same area on a small upland and about another 10 square feet will replaced by riprap to prevent erosion and solids going into the wetland ecosystem. This will also increase flood storage during severe storms.
Chairman Jason Moran asked why the application stated it "emergency road repairs" and thus was exempt from state stormwater standards.
Murray said it functions as a road and is in need of emergency repair because of the flooding situation.
"As you're well aware, most stormwater reports cover situations of how to handle new impervious area, and none of that is occurring at this site," he said. "So going through all the standards is pretty minimal, given the fact that there's nothing new being created."
Moran also asked about how the system would be taken offline to prevent damage if there rains during the replacement. Murray said a bypass would have to be put in place but the work would largely be done during good weather. The flood level at the outlet has also been determined by the Federal Emergency Management Agency to be lower than any existing building in the area.
"You guys are doing a wonderful job for the protection of Wood Street, Mass Ave, and Ashton," Moran said, but "because you are introducing, while the amount of water may still be getting to the same location, the velocity of the water that's going to be going there now is going to certainly be increased with the pipe size."
The 25-30 foot long riprap channel will dissipate much of that energy, said Murray, "By the time it starts getting beyond the riprap, it will be at a velocity that's not going to be scouring the sides or bottom of the existing culverts."
That will of course require that the inlets be cleaned and maintained, he said.
Commissioners also asked about the invasive species in that area. Murray said they would be removed from the area being disturbed by the project but if the city had a budget, there could be more extensive species removal.
"There may be the opportunity for more invasive species removal, as other other areas get disturbed but that's in the future and that's not associated with the project," he said.
Murray expected the project to be bid out to begin in the spring and said Waterfield would be on site at least once a week and would be there for the more "significant items" such as the entrance and exit installations.
The commission approved the project and set conditions that some erosion control be maintained, particularly near the McClain building where there is a manhole, removal of invasive species in the work and replication areas with a five-year standard monitoring report. The commissioners also asked for an effort to do the work during low water or dry periods.
Tags: conservation commission, flooding, stormwater,
