UNH stormwater experts give Tisbury infrastructure update


Members of the University of New Hampshire (UNH) Stormwater Center gave a presentation to Tisbury town officials and members of the public about best management practices for a number of problem drainage areas.

The UNH Stormwater Center, through a watershed assistance grant, has been working alongside the Massachusetts Department of Transit and the EPA to evaluate Tisbury’s wastewater infrastructure and develop a construction and maintenance plan. 

The first area stormwater experts addressed was the area near Beach Street Extension that, according to program director for the stormwater center at UNH, James Houle, is a top priority.

Due to high volumes of stormwater runoff, steep slopes, and large impervious surfaces, the intersection at Five Corners sees frequent flooding.

“We can’t escape the problem at Five Corners. People say it isn’t an emergency, yet whenever there is a storm it causes huge problems,” Houle said.

Houle said the objective of their proposed design would be to reduce the amount of sand that clogs the outfalls during high tide and during major weather events.

Even as the presentation was going on at Katharine Cornell Theater, town workers were digging out the outfall ahead of a wind storm Friday night.

A number of innovative concept designs for stormwater maintenance were presented by the UNH Stormwater Center, including an oil and floating debris trap called “The Eliminator,” which allows for easy installation and is partially manufactured with recycled materials. 

Houle also told the audience about generic leaching catch basins, and subsurface gravel filters that can replace your everyday deep sump catch basin and infiltration trenches. 

Another problem area identified by stormwater experts was the end of Grove Avenue, where steep slopes produce high-velocity runoff that flows into sandy beaches, causing erosion. 

Houle suggested a closed bottom leaching catch basin that would replace typical solid catch basins in order to improve drainage and allow for easier maintenance access.

Houle said implementing these stormwater technologies would diminish much of the flooding seen at Five Corners and other areas within the floodplain.  

And he said that if Tisbury is able to start working on some of these stormwater issues, it will galvanize other towns to do the same.

“Once they install one or two of these systems, I imagine it will spread to the other towns once they realize how well it works,” Houle said.