Will the Boston Harbor ocean barrier rise again?
Built on four centuries of filled land, Boston is wildly vulnerable to the next major hurricanes or winter northeasters. These risks only accelerate as storms get worse and sea levels rise. To their credit, the city and state understood this exposure years ago and have been steadily working away on climate resilience initiatives. One project was to consider a grand Boston Harbor barrier that would close off much or all of the harbor against big ocean storms. A study led by the University of Massachusetts found, however, that such a barrier would be thoroughly impractical.
But maybe not. William Golden, famous here for kicking off the legal struggles that triggered the harbor cleanup a few decades ago, today launched an open meeting of a Boston Harbor storm surge working group. The group’s premise is straightforward: the best defense against the sea is a layered defense that combines a re-thought harbor barrier (to fend off the storms) and relatively modest local measures such as berms and seawalls (to handle sea level rise).
Among points by Golden and his allies:
- There are many alternative barrier routes and designs, some sketched out above by Duncan Mellor of Tighe & Bond. These might mostly follow shallow water, use dual gates for the shipping channels rather than the never-built-anywhere single gate structure examined by UMass researchers, and be considerably less massive. That might make them dramatically less expensive than the $7-12 billion pricetag UMass experts suggested.
- Depending on your assumptions about how long construction takes and what you pay for money (discount rates), costs again might drop significantly. And unlike smaller projects, federal funding just might be available.
- A barrier that guards the entire harbor, not just Boston, could provide benefits that no one has counted yet. Most dramatically, the savings in regional flood insurance payments might be many times the investment.
- The default alternative of building high local berms/seawalls everywhere brings up seriously worrying questions. For one, what about the places that can’t afford them? For another, how will all these patchwork walls connect? And do we really know how to efficiently build a watertight 20-foot seawall all along, say, the North End waterfront, with its crazy web of buried infrastructure and weak geological underpinnings?
Our safeguards against the sea will have domino effects far beyond Boston. “This is going to affect the economy of the whole region,” Golden said. “It’s an existential threat.”
Pre-filled Boston, courtesy Leventhal Map & Education Center, Boston Public Library
The Thames Barrier is still prepped for decades defending London against high water.
On Tuesday, the warmest winter day ever recorded in Britain, there was not a cloud in the sky over the Thames Barrier. A tug calmly pulled its barge through one of the channels in the Barrier, which shuts off the Thames when the incoming tide will rise over sixteen feet. This offbeat superdam doesn’t look like anything else: a necklace of giant steampunk silver mussel shells stretched a third of a mile across the river. London began seriously contemplating means of protection after a major dousing in the great North Sea storm of 1953. The Barrier went into operation three decades later. It has decades of usefulness ahead; although climate change was not considered in its design, sea levels along the southern English coast aren’t inching up from geologic causes as fast as originally expected. The Barrier has been shut about 200 times, 50 of them in the 2013/2014 season, when the culprit was not super surges from the ocean but super rain surges that incoming tides would have pumped up further. “It is designed to be bomb-proof and failure-proof,” the Londonist once noted. “When a 3,000-tonne dredger hit the Barrier in 1997, the ship sank. The Barrier lost a ladder.” One of these decades, the enormous wall may be supplemented by a much more enormous dike downstream. In the meantime, “the structure is fundamental to the lives of millions of Londoners,” the London Review of Books commented, “which may be the reason very few of them want to look at it.”
A beacon of hope in a changing climate.
On a clear hot August day you can take a ferry to Spectacle Island and walk a winding path up to its northern summit, admiring wildflowers and eating blackberries. The summit is the highest point of land on Boston Harbor, with low wooded islands scattered around.
Off to the east you can spot a windmill near the huge sludge-digesting eggs of Deer Island, and a second windmill a few miles south at the tip of the Hull peninsula. These two points of land bracket the entrance from Massachusetts Bay to the harbor’s inner archipelago.
One distant day, Deer Island and Hull also may anchor a massive sea barrier, holding off an ocean that’s now projected to climb as much as eight feet by 2100.
Today it’s hard to imagine how we might start to build such a Big Dike, given our current politics.
But you can also see hopeful signs on this Spectacle for our ability to clean up our own messes.
The first time I sailed past the island it was a garbage dump, with the remnants of a horse-rendering plant buried under many feet of still-smoldering refuse.
Now that’s all taken away and replaced by fill from the Big Dig. The island was reengineered and replanted. Rich ecosystems began to reappear. On summer days like this, children swim a stone’s throw away from the site of the old factories.
In wildness is the preservation of the world, as Thoreau said. But not just in wildness.