Wrong side of the river ( part 2)

There’s also the pollution. “Every bit of dirt that we have to take off the site and throw away is expensive, because it’s contaminated with metals and other things,” says the environmental scientist Justin Reel of RK&K, who leads mitigation and hydrological planning for the project. “But for the low-level type of human interaction we’re proposing, with a fairly thin cover we can use it on the site effectively. If you don’t have frequent, regular, intended exposure, these contaminants aren’t super bad. Where we do anticipate frequent soil contact, like our upland islands, we are planning for a cover over top of any native soil.”

[caption id="attachment_236" align="aligncenter" width="618"] South Wilmington Wetland Park Master Plan[/caption]

A single strategy

But resolving the polluted soil problem will be complex. “It’s one thing to clean up an area for humans. But if you’re bringing burrowing animals in, or shellfish,” a more stringent standard might be required, says Marian Young, the president of the remediation consultancy BrightFields. Scarfone quips, “For the amount of remediation we need, all the earthworms in the world aren’t going to be able to do.” Normally, he says, “for projects like this, you cap it. But here, we want to re-create a functioning system.”

This spring, the future park was cleared of dense Phragmites. The resulting open, savanna-like vista gave a delightful hint of how it might eventually look—or feel, anyway, because it has yet to be sculpted and engineered.

[caption id="attachment_237" align="aligncenter" width="657"] Industrial detritus and invasive vegetation have occupied the site until now.[/caption]

Added water storage capacity and created habitats that can resist recruitment of invasives like Phragmites will both be achieved with a single strategy, lowering the site to alter the hydrology and establish “a different water regime than we have right now, which is very irregular and storm driven,” Reel says.

When there is a flush of stormwater from the residential neighborhood, it will collect in a forebay, to let sediment settle, and then will cross the site through a winding network of channels and ponds. These eventually converge on a short, straight connection from the park to the river that is partly open ditch and partly pipe.

At the river, the flow, as it is currently, will be controlled by a self-regulating tidegate. An open flow to the Christina and its tides was considered. That would promote the wetland’s naturalization and its connection to fisheries. But properties surrounding and contiguous to the park are low-lying.

Wrong side of the river ( part 1)

The Christina River is a tributary of the mighty Delaware estuary, close enough to the ocean that it is tidal. It meanders through Wilmington like a wobbly M. Most of the city sits on the north shore. As long as anybody can remember, the lowerlying south side has experienced periodic inundation; 90 percent of it is within the 100-year floodplain. The first European settlers, being Dutch, were undaunted.

They built dikes and ditches there, and grew salt hay for fodder. Iron mills, coal yards, tanneries, and other nastiness arrived on the south shore throughout the 19th century and into the 20th, mostly located along the river’s edge. Mean-while, in the marshy center of the M, according to an 1893 newspaper item, there were eight or 10 “flower farms,” the largest named Rushland Gardens.

[caption id="attachment_229" align="aligncenter" width="1268"] RANDALL’S ISLAND The trestle beneath Hell Gate Bridge on New York’s Randall’s Island,[/caption]

A street grid was platted for this whole river-bound southern piece of Wilmington, but only a sliver of it, a neighborhood called Southbridge, was ever developed. In 1900, when the city’s total population was nearly 77,000, about 3,000 people lived south of the Christina.

Many were recent immigrants, and some were African Americans with deep local roots; the first independent black Christian church in the United States, the Union Church of Africans, had been founded there by a former slave in 1813.

Today, industry in South Wilmington appears to consist largely of auto junkyards and storage lots for disused trailers and shipping containers.

[caption id="attachment_230" align="aligncenter" width="465"] High tides and a clogged sewer overflow system frequently combine to flood Wilmington’s low-lying Southbridge neighborhood.[/caption]

Recently there’s been some growth—a shopping center with a supermarket, and a waterfront town house and apartment-tower complex built along the northwestern edge, facing over the Christina to downtown and the city’s thriving Riverfront redevelopment district.

Half a mile east, though, across the wetland, Southbridge feels like an isolated village. Its population has dwindled to about 1,500, nearly all of whom are African American. But it’s a place with a certain integrity. Many families have lived there for generations.

Nearly half the homes are owner occupied. There is an active and effective neighborhood association. Still, it floods. Now there is a plan to transform the marshy center into South Wilmington Wetlands Park. It’s not exactly a new proposal. A 2006 neighborhood plan offered a description that still applies: “Create a Central Park located to the immediate west of Southbridge.

Use this park as the lungs of the neighborhood. Its wetlands should be cleaned up and improved for flood retention.” But flooding is not the neighborhood’s only challenge. Southbridge is more or less surrounded by brownfields left over from those 19th and early 20th century heavy industries.

Near by jobs are few. It’s a food desert, with public health issues typical of underserved urban communities with an industrial past. The park vision has been enhanced since 2006, with a plan for added street connectivity around the wetland, and with realizations that a cross park trail will link the neighborhood directly to the shopping center and groceries.

The park could be an engine of investment, not only for Southbridge, but also for all the nearby underused properties. That could mean infill for new residents and businesses, and new jobs. Another added dimension: The concept of how to handle the wetland itself has been taken far beyond the basics of cleanup and water retention. The source of the flooding, aside from low elevation and inexorably rising tides, is an overwhelmed combined sewer system.