Rain Garden by Rain Garden, Hoboken Builds Resilience

After Hurricane Sandy devastated the city of Hoboken, New Jersey, six years ago, city leaders got serious about resilience. The one-square-mile city is vulnerable to coastal and stormwater flooding for several reasons: low topography and proximity to the Hudson River; extensive impermeable ground cover; and aging sewer infrastructure.

In the post-Sandy Rebuild by Design contest, the international architecture firm OMA and partners won a grant of $230 million to rebuild Hoboken. At the same time, the city embarked on multiple complementary resilience initiatives, including new design guidelines for buildings, a hazard mitigation plan, and a green infrastructure plan that guides development of resiliency parks.

Green infrastructure encourages the natural movement of water by collecting it and diverting it to engineered natural systems. On a recent tour of Hoboken’s green infrastructure, sponsored by the SWIM Coalition, participants got a close look at the city’s progress on resilience projects.

According to Caleb Stratton, Hoboken’s chief resilience officer, the city has invested $100 million in green infrastructure, with $50 million in projects in the pipeline, and another $150 million set aside for the full build-out.

He described Hoboken’s four-part water management strategy—called Resist, Delay, Store, Discharge—and the role of green infrastructure in it. New resiliency parks anchor the edges of the mile-square city, beautifying the landscape with absorbent greenery while mitigating flooding with porous pavers and underground stormwater detention systems. Rain gardens and green roofs dot the cityscape.

The tour began at Hoboken’s City Hall where downspouts have been rerouted into cisterns, rain gardens planted on all sides, and some of the surrounding pavement is permeable. A highpoint of the day was hearing what Tedx Talk star Dr. Elizabeth Fassman-Beck, a professor at Stevens Institute of Technology, had to say about cutting-edge design of green infrastructure.

“My number one outcome is to soak up a lot of water,” she said, gesturing toward a campus rain garden. “Where does the water come from, how much land area drains to it and how does it get there, and how does it get out? Right now, the calculations and assumptions that you make for designing most green infrastructure are really rules of thumb. Rain gardens are not designed dynamically. In other words, we know water moves in and out of that system at the same time–water’s draining out at the same time runoff is coming in. But the design assumptions are that you have to capture all this water in the system and then you allow it to drain. It doesn’t work like that, and it means we are treating a lot more water than we think.”

On the tour, some of the New Yorkers were impressed with what they saw as less complicated resilience strategies employed in Hoboken. Shino Tanikawa, executive director of the SWIM Coalition, liked the “elegantly simple” and inexpensive floats in New Jersey’s combined sewer overflow system that trigger real-time alerts when the water rises. A staffer from the New York City Department of Transportation appreciated the vehicle-friendly slopes of concrete that direct street run-off, compared to New York City’s clunkier concrete lips.

The camaraderie and exchange of ideas on the green infrastructure tour of Hoboken—engineers talking with government agency staffers, professors talking with green business representatives, designers talking with sewage utility workers, New Yorkers talking with New Jerseyans—was just what Ms. Tanikawa hoped for.

“Networking can change our perspectives and produce more creative thinking,” she said.

Photograph courtesy of Stevens Institute of Technology.