Sandwich Coastal Flooding Assessment

The multicolored line that follows the railroad tracks along the coast of Sandwich and Barnstable indicates an existing barrier that could be bolstered by natural (vegetation and sand) and/or man-made elements (such as gates) to provide protection against storm surges, according to Woods Hole Group, the town’s beach consultant.

While the town’s beach consultants are working with state and federal authorities to replenish sand on Town Neck Beach, they are also studying the flooding dangers along Sandwich’s vulnerable coastline.

Representatives from the Woods Hole Group and Kleinfelder, Inc.—an environmental engineering company—showed dramatic slides and graphs to a handful of people who turned out on Wednesday, October 23 at the Sandwich Public Library to hear an update on the groups’ study into the town’s coastal vulnerability.

The study examines flooding damage from major storms in the present day and then projected what could happen 10 years, and then 50 years, from now.

The Route 6A fire station, which was flooded during the March storms of 2018, was identified as an extremely vulnerable town structure.

Natural Resources Director David J. DeConto, who attended the presentation, said that during the most severe 2018 storm, water pooled deeply on Route 6A and swept into the fire station garage whenever the doors were opened.

“Our drainage systems are just not designed for this; they were completely overloaded,” Mr. DeConto said.

The consultants showed other dramatic renderings of Route 6A, which could, in the not-so-distant future, be completely under water for days after a major storm event.

If the town takes no measures to shore up the beach and the marsh, the configuration of the area would change over time and its ability to absorb the extra flood waters would greatly diminish. Route 6A and the neighborhoods around it would experience prolonged saturation from floods, the consultants said.

Although the town is already experiencing some of these effects from sea rise and climate change, it is expected to become dramatically worse, the consultants said.

Measures to elevate and protect such flood-prone areas with vegetation, berms and drainage ditches are the first line of defense, the consultants said, but they are expensive.

The town must weigh the costs of that protection, which can range from several hundred thousand dollars to millions, said Joseph Famely of Woods Hole Group.

“Our team was looking at town assets and how to protect them,” Mr. Famely said. “We gathered data on floods and the impact of those floods.”

Mr. Famely, and Julie Conroy of Kleinfelder, briefly outlined four strategies for combating the effects of flooding from snowstorms, northeasters, sea level rise and erosion.

The strategies are: Avoid, Accommodate, Protect, and Retreat.

Avoidance would be the least expensive solution and would involve prohibiting activities such as new building or the disturbance of natural elements in the flood zone, the consultants said.

Accommodation would involve raising structures above the expected flood path, remodeling with flood-proofing materials, and strengthening building codes.

Protection, which is the most expensive option, would involve building sea walls, adding vegetation and creating dunes—natural and man-made. This category could also include building metal gates, or a series of metal protective structures that can be opened and closed before and after storms, Mr. Famely said.

A slide of a regional protection solution depicts the railroad tracks that run between the coast and Route 6A in Sandwich. That support structure could be beefed up with vegetation, sand or a series of movable gates that could be closed during major storm events, the consultants said.

When all other considerations have failed, the town must consider Retreat—or abandoning assets at risk. Officials in other coastal areas have already begun such discussions, Mr. DeConto said. Among those are Scituate Beach and Chesapeake Bay.

“It’s not something Sandwich is experiencing at this point, but it’s something to begin thinking about,” Mr. DeConto said.

All the research will be made available to the public in the next few weeks. Hard copies of the consultants’ report will be available at the library’s circulation desk and the slides and charts will be posted soon on the town website, Mr. DeConto said.

Ultimately those maps will be interactive and will depict how flooding would affect vulnerable sections of town over time—including the beach, boardwalk and the village.

An education grant will also allow Sandwich High School to develop and incorporate coastal vulnerability studies into its curriculum, Mr. DeConto said.

The workshop and the online information was made possible by a $46,000 state grant to educate the public about Sandwich’s coastal vulnerability.

The grant was the third allotment to Sandwich from the state’s Municipal Vulnerability Preparedness program.

Earlier this year, Woods Hole Group was able to use a $117,000 grant to identify the town’s most vulnerable municipal structures.

The data showed that the fire station on Route 6A is extremely vulnerable, and measures should be taken immediately to protect it and the outbuildings and propane tank on the property.

Other assets on the endangered list after big storms are the former police station on Route 6A, the town hall, the Dexter Grist Mill ticket booth, the Sand Hill Community Center and the East Sandwich Fire Station, Mr. Famely has said.

“The action grants are being awarded to cities and towns across the commonwealth for projects to improve their resilience to climate change through the Municipal Vulnerability Preparedness program,” a spokesman for the the Executive Office of Energy and Environmental Affairs said last year.

Mr. Famely said earlier this year that winter storms will continue to gobble up more of the coastline, spring seasons will be wetter and summers will be hotter.

Sandwich is even more at risk than some other Cape towns, the study has found, because of its proximity to the Cape Cod Canal.

The beach, the harbor and the historic village, all of which keenly felt the wrath of the 2018 winter storms, are particularly vulnerable, the study found.

Sandwich was one of the first towns on the Cape to enlist in the Municipal Vulnerability Preparedness program, Mr. DeConto has said.

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