Lenox Conservation Commission
Landuse Meeting Room
December 4, 2014
Minutes
Town Hall
Members present: Chair Neal Carpenter, (NC); Vince Ammendola, (VA); Tim Flanagan, (TF); Joe Strauch, (JS); Dick Ferren, (DF); Rose Fitzgerald Casey, (RFC); David Lane, DL
Staff present: Gwen Miller, Land Use Director/Town Planner, (GM); Peggy Ammendola, (PA)
Ethan Berg, 107 Yokun Avenue, Map 12 Parcel 2-1, review solutions to detention basin failure. Continued from November 6, 2014.
Present were Ethan Berg; Mike Kulig, Berkshire Engineering; Michael Sucoff, Construction Manager; and Mike Mugridge.
Mr. Kulig stated that as a result of studying the situation on this site from different angles, and having numerous discussions on possible remedial actions, he was proposing to the Commission two components. One would be to increase the size of the holding basin and the other would be the handling of the erosion down the slope. The erosion has deep and shallow areas of scouring. The plan would be to work up from the bottom of the slope. At a site visit attended by the Commission and Mr. Kulig, all agreed that the deeper areas of erosion will require more attention than the shallow areas. He proposes that the basin be sized to accommodate a 25 year event as there is ample space to accomplish this. The original basin was supposed to be 35 feet by 30 feet and would handle a 2 year storm.
The proposed holding basin would be six times larger and could handle a 25 year event providing capacity in the water way so that it will remain stable.
Mr. Kulig asked the Commission if this project could proceed informally or if a filing would be required. TF responded that prior to commencing of work a filing would be required along with plans for the proposal and submitted for review for compliance. TF added that the Commission is happy to have this dialogue and discussion at this point as the Commission does not want to see time and money wasted on a design that will not work.
NC questioned the proposed progression, going from the bottom to the top, to repair the washed out channel areas. Proceeding in this fashion, he said, would likely require more extensive clearing and disturbance in the work zone than proceeding from the top down. Mr. Kulig said that believes the remedy would be to partially fill in the deep scoured areas and widen the channel to create a waterway with enough volume to handle the 25 year event.
TF asked about the watershed and the configuration of the catchment area. Mr. Kulig said that the watershed that feeds this area is about 8.6 acres and some stormwater comes from other properties. TF asked Mr. Kulig if he saw any opportunities to slow down the flow to the basin and to disperse it before it got into the basin. Mr. Kulig said that after looking at the situation he felt that there were some possibilities for accomplishing some infiltration and dispersion of stormwater above the holding pond but that it would be a separate project in itself to accomplish. Mr. Kulig felt that the accumulated water could be handled by the proposed upgrade of the current system.
With regards to the eroded areas, originally it was thought to fill to grade, but Mr. Sucoff said that he felt there would be more harm than good if the entire area was filled in. Mr. Kulig said that his thought would be to fill it in part way and reinforcing with fabric and rock. They would use impervious borrow, a silky type soil, that once in place it will stay. He doesn’t think there is a need to widen, so he proposes to work with the existing width. He would include check dams every 30-40 feet, force breakers that would slow the force of the water so as to allow the water to infiltrate The Commission feels the channel should not be completely filled. TF said that one of the design goals is that this channel will have to carry the amount of storm water that travels out of the basin in an extreme
event. As a point of discussion, he asked, if we go with a 100 year event, 18 inches or 2 foot depth with this existing width would that be sufficient to carry that amount of water? He advised against carrying this too deeply because then there would be side cutting and the need for having rip rap up the side. He suggested a good target for this design would be keeping a minimum depth and fairly wide by building it up within 2 feet. With such a design he feels that the final profile would be parallel to the existing hillside, deeper a little bit, so that it would not have breaking out on side. Too deep a center would make it more vulnerable. TF said he would favor that kind of approach, from top to bottom. In speaking about the basin design, Mr. Kulig said that he is considering designing a basin that will follow more closely the contours of the existing land. It would be designed to manage the 2, 10 and 25 year storm events and further the
ability to handle the 100 year storm event by reinforcing the wall structure to permit overtopping without wall failure. Further discussion on the channel brought up the probability for the need to include check dams at various intervals to control the force of the downhill flow to prevent future scouring of the channel.
At the end of the main channel, there are several distributary channels. TF suggested that the work stop at the head of debris fan let it re-vegetate.
MM expressed concern about re-vegetation with the existing canopy as he feels for optimum growth, there needs to be more sunlight. TF responded that it depends on how much you want to open up, but he would be a little nervous about too much tree cutting. He asked that Mr. Mugridge show this on the plans to be submitted.
The Commission emphasized that they cannot design a project, but to review for compliance. DL stated that when the Commission receives the plans, they will need to go for another site visit to really see what is going on from the detention pond down.
MK said that they want a design that will be more sustainable than the existing and make sure the channel remains stable. He stated that the Commission had been helpful in developing ideas.
The Commission felt that the design team was heading in the right direction and recommended that they return with proposed plans for remedial action. The Commission also asked that the team provide measurements on plans showing existing widths and depths of the channel.
It was agreed that this matter would be placed on the January 15, 2015 agenda.
Approve Minutes-November 20, 2014-TF made a motion to approve the minutes and RFC seconded the motion. The Commission voted to approve the minutes 7-0.
RFC made a motion to adjourn at 8:34 PM. JS seconded the motion and the Commission voted to approve 7-0.
Respectfully submitted,
Peggy Ammendola
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