According to Art Christian, head of the Dam Safety and Maintenance at the Department of Environmental and Energy Protection, the flashboards at Windsor's Rainbow Dam broke for the second time this year Monday, adding to floodwaters already breaching the banks of the Famington and Connecticut Rivers.
Flashboards, Christian said, are wooden structures (six feet high at Rainbow Dam) that allow the reservoir to hold more water. The wood structures are used mostly at hydro-power dams, he added, and allow a dam to harness more energy.
During periods of heavy rains or runoff, waters may exceed the reservoir's natural holding capacity, reach the flashboards and cause them to break, allowing the dam to release water and the excess pressure that came with it without having to open the dam's gate.
While the feature added to the amount of flooding, it also prevents excess flooding and damage to the dam itself.
The breaking of flashboards can happen very quickly, Christian said. His staff paid a visit to the dam around noon Monday to check the water level and the dam's condition, left the area, and by 1 p.m., the flashboards had broken away.
The dam worked "as designed," Windsor Town Manager Peter Souza said early Tuesday.
The interesting thing about Monday's flashboard break, Christian said, was that it was the second time this year that Rainbow Dam's flashboards have given way. The first time was this spring after the snow melting that caused the rivers to rise and many basements to flood.
When flashboards break, Christian said, they are replaced with a new structure atop the dam.
As of Wednesday morning, both the Farmington and Connecticut Rivers crested and are in the process of receding.