Impact of Delaware River deepening

    How will the environment fare if the river is dredged?

    Should the Delaware River be dredged south of Philadelphia? That question has been debated for two decades. Proponents say deepening the shipping channel would bring new jobs to the regional port. Opponents fret about environmental harm. The Army Corps of Engineers says 2009 could be the year the project finally happens.


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    The Shuman is a 65-foot-long aluminum catamaran. It cruises the Delaware River every day, scoping out mile after mile of river bottom.

    View from the Shuman's deck
    View from the Shuman's deck
    Griffith: What we have is a display of the bottom. This is what the actual bottom looks like.

    George Griffith is the Philadelphia Army Corps of Engineers’ survey tech for the Shuman. He points to a computer screen in the captain’s cabin that shows images that look a bit like the surface of Mars. Joe Scolari is the group’s head of surveys. He says new technology gives him a look at 100 percent of the river bottom, way better than the old way, which scanned only cross-sections.

    The Shuman prepares to leave dock
    The Shuman prepares to leave dock
    Scolari: You’re doing a profile every 400 feet. or cross section, depends on what terminology you want to use…That means 390 feet in between there’s no information….In between the cross sections there’s a lot of missed data and potential for trouble.

    The old approach had flaws. For example, it missed a giant submerged anchor that caused an oil spill in the Delaware River in 2004. The improved equipment has also shown that the river is actually deeper than previously thought, says Anthony Di Pasquale, the Corps’ chief of operations in Philadelphia. And a deeper river means less dredging.

    View from Shuman's Bridge
    View from the Shuman's Bridge

    The perception is we’re taking this massive dig project when in reality there’s very little material that needs to be excavated.

    The Army Corps’ proposed dig would deepen the river’s shipping channel to 45 feet. In 1997, the Corps thought that would mean digging up and carting away 33 million cubic yards of mud and rock. But now that estimate is less than half, at 16 million cubic yards. That’s just one of many big changes in the 20-year-old plan, says Steve Mars. He’s a senior biologist with the US Fish and Wildlife Service.

    Mars: The big thing that the Service is concerned with is that much of the environmental documentation for the proposed dredging is based on data that was gathered in the 1990s.

    Mars says one concern is how the dredge might impact horseshoe crabs. Their eggs feed the recently threatened red knot shorebird. Other environmental concerns linger. Danielle Kreeger is the science director for the Partnership for the Delaware Estuary. She worries that removing sediment could harm salt marshes and flood control.

    The scanner bay on the Shuman
    The scanner bay on the Shuman

    We’ve learned lessons from the mouth of the Mississippi from Katrina where the same sort of effect has happened. And that’s been one of the major reasons why wetlands have been some catastrophic losses down there.

    Environmental advocates are frustrated. Maya van Rossum is the Delaware Riverkeeper. She says the Army Corps hasn’t addressed their concerns.

    van Rossum: The state of Delaware should deny the subaqueas lands permit, because we don’t have all the information we need in terms of ecological implications.

    Delaware is weighing a permit application from the Army Corps to start digging. Pennsylvania backs the project, but New Jersey has had reservations. Van Rossum says a prime concern is that poisonous chemicals might leak from the dredged material.

    Multibeam scan

    van Rossum:
    There will be toxins reintroduced into the main stem Delaware River, in a food chain that already is over-inundated with things like PCBs, and heavy metal, and DDT.

    But that fear is unfounded, says Tom Fikslin, modeling manager at the Delaware River Basin Commission.

    Fikslin: One of the things that dredging does do is it removes that contaminated sediment and puts it into a place so it’s actually providing a benefit in terms of removal of this material.

    Biologist Steve Mars says other states have pulled off similar dredging.

    This project is no different than some of the other port deepening projects that are happening on the East Coast, in New York harbor or Baltimore harbor or Norfolk.

    Mars agrees that dredging may be possible without too much damage to the environment. But he says the Corps should prove it, first.

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