NewburyportNews.com, Newburyport, MA

March 8, 2013

Jetty work site takes a beating from storm

STAFF REPORTS
Newburyport Daily News

---- — PLUM ISLAND — As islanders fight to shore up their homes along Annapolis Way, another battle against erosion is taking place at one of the most inhospitable parts of the island — the northeastern tip.

At this spot, where the Merrimack River spills into the ocean and the 2,445-foot-long stone jetty is being repaired, workers yesterday used heavy equipment to build a temporary storm wall out of massive rocks that are slated to be used to fill holes in the jetty. They also removed sections of a temporary road made from one-foot-thick wooden beams that is used to transport the boulders across the dunes to the jetty.

The workers were attempting to protect the dunes and the jetty repair project’s road from a sudden surge in erosion. About 25 feet of shoreline next to the jetty disappeared yesterday morning, torn away during high tide by the powerful river current that the repaired jetty generates. More dune is expected to be lost by the time the storm subsides later today.

As they worked, the conditions on the open dune were miserable — 30 mph-plus winds blew fiercely, kicking up a cloud of sand that sandblasted everything that moved.

The workers were not allowed to speak with The Daily News per orders from the Army Corps of Engineers, which is managing the project. Calls to the Army Corps were not returned yesterday.

In recent meetings, erosion in the rivermouth near the jetty was pinpointed by the Army Corps of Engineers as a likely consequence of the jetty repairs. In the complicated dynamics of wind, currents and waves that occur on the coast, the repaired jetty is expected to encourage sand to migrate along the oceanside of Plum Island, perhaps saving areas where erosion is imperiling homes. But at least some of that sand will come from the erosion that is happening now at the island’s northern tip.

When first built in the late 1800s, the massive stone jetties were designed to create a funnel effect, which was intended to increase the velocity of water that moves through them and keep open a deep navigation channel through the river mouth. But they also have a tendency to erode the dunes at the northernmost end of Plum Island, where the funnel shape of the island’s jetty begins.

The jetties have not been repaired since 1970. In the years immediately following that repair, the northern end of the island underwent a similar phenomenon — dunes eroded through the funnel, pushing the shoreline southward toward hundreds of homes. Problems with erosion there peaked around 1975, when the City of Newburyport built an emergency wall made from concrete blocks to save homes, some of which were only 10 yards or so from the water’s edge. Since then, the dune has gradually grown, and now the water’s edge is about 200 yards or more from those homes.