Engineer recommends wider corrugated arch pipe and paved swale to reduce flooding at Bellman Falls underpass

Robert Clark, an engineer with Auto Creek Engineering, told the Town of New Haven Select Board on July 21 that vertical clearance and bedrock conditions prevent raising the road under the railroad trestle and that regulators are unlikely to permit a controlled-storage pond at the site. He said the practical compromise is to maximize the cross‑sectional opening and pave a swale under the trestle so overtopping flows run down pavement into the existing overflow path.

"Our thought with that is actually to not put a gravel road back but to pave the road back underneath there and essentially pave a drainage swale in there and design a controlled flow," Clark said, describing the overflow path the town would rely on in extreme events. He added the preferred construction would use the widest possible corrugated arch pipe with custom fittings to accommodate the skew of the culvert relative to the road and tracks.

Clark outlined limits and tradeoffs: municipal design practice commonly plans for 25–50‑year storm events and tries to avoid designing for every extreme (100‑year plus) flood; the existing configuration means overtopping will still occur in very large events. He warned a concrete cast‑in‑place deck would be more durable but cost more, and that rail and dam infrastructure plus nearby residences constrain construction access and schedule. Clark said he expects a shorter construction duration and lower cost by choosing the arch pipe approach and will provide a plan and cost estimate for permitting and bidding.