Commentary: Delaware Bay oil spill cleaned but remains a mystery

By Frank Csulak

On a relatively quiet afternoon Oct. 19, the U.S. Coast Guard notified the National Oceanic and Atmospheric Administration that tar balls and oiled debris were scattered across approximately 12 miles of the Delaware Bay’s shoreline. As the scientific support coordinator for the mid-Atlantic region in NOAA’s Office of Response and Restoration, I am used to such calls and began working with my team on the trajectory, weather and tidal information.

Frank Csulak

The impacted area in the bay extended from Prime Hook National Wildlife Refuge to Cape Henlopen. In the spring, this area provides habitat to hundreds of thousands of horseshoe crabs that come ashore to lay their eggs, followed by the arrival of tens of thousands of migrating birds — specifically the red knot and oystercatchers, two federally protected endangered species that feed on the horseshoe crab eggs. Because of these species, NOAA also provided an informal endangered-species consultation.

However, within a few days of the initial tar balls washing ashore, those 12 miles of oiled shorelines turned into more than 60 miles of impacted shoreline — extending from Prime Hook to Cape Henlopen State Park to Fenwick Island, then south to northern Assateague Island, Virginia.

In addition to the Coast Guard and OR&R’s Emergency Response Division, additional agencies and organizations that responded to the oil spill included the Delaware Department of Natural Resources and Environmental Control, the U.S. Fish & Wildlife Service, the Maryland Department of the Environment, the Virginia Department of Environmental Quality and Tri-State Bird Rescue & Research. Lewis Environmental was contracted by the Coast Guard as the oil spill-response organization to provide the manpower and equipment to remove the oil from the impacted shorelines.

Examples of tar balls that came ashore on Broadkill Beach. (NOAA photo)

To date, the Coast Guard has not been able to identify the source of the spill. As a result, Coast Guard Sector Delaware Bay opened the Oil Spill Liability Trust Fund to cover the costs of the response. Initially, it was thought that several vessels involved in a lightering operation in the Delaware Bay a few days prior to the oil coming ashore may have been the source, but after collecting source oil samples from these vessels, including tracking one vessel to Corpus Christi, Texas, the Coast Guard’s Marine Safety Lab in Connecticut was not able to “fingerprint” a match between the source oil samples and the field samples. NOAA also made arrangements through Louisiana State University’s chemistry department to analyze the tar balls. Laura Basirico, an LSU chemist, concluded that the oil was a “fresh” oil, probably a refined high-aromatic heating or diesel fuel oil.

Since there are several nearby wrecks offshore from New Jersey and Delaware, that raised the question of whether one of these wrecks, especially those that were sunk by German U-boats in the early 1940s, could be the source. Christopher Barker, an oceanographer at OR&R, prepared several different trajectory models using these known wrecks as a potential source.  The modeling showed that it was extremely unlikely that any of these wrecks were the source.

Satellite imagery of vessel wrecks offshore of Delmarva and New Jersey.
(Photo by Juan Velasco, NOAA)

We also reached out to NOAA’s National Environmental Satellite, Data, and Information Service Satellite Analysis Branch (NESDIS). NESDIS operates a fleet of environmental satellites that provide critical worldwide imagery of significant weather and environmental events. For this case, we reached out to Juan Velasco, an ocean remote-sensing operations officer in NESDIS, for imagery support. Even with several days of excellent satellite imagery of the shipwrecks located off the coast of New Jersey, Delaware and Maryland, imagery did not detect any oil leaks from the vessels. To further support the Coast Guard’s efforts to identify a source, U.S. Coast Guard District 5 arranged for C-130 fisheries flights to fly over the wrecks as part of their patrol missions, and the fishery flights did not detect oil being discharged from the nearby wrecks.

With regard to the old question, “How clean is clean?” in terms of removing oil on the beaches, Jacqui Michel, a NOAA contractor, recommended that the cleanup endpoint for this spill be to remove all tar balls larger than dime size or larger than 3 centimeters and to remove all oiled debris. Employing mostly manual removal, with the use of some mechanical beach rakes, all visible oiled wrack and tar balls were removed by the contractors — totaling 85 tons.

As of Nov. 13, the Coast Guard deemed the response complete along all Delaware, Maryland and Virginia shorelines.

In summary, this spill response demonstrated a successful collaborative effort of the first responders, assessment teams, investigators and response workers, who spent weeks cleaning the shorelines of Delaware, Maryland and Virginia. The collaborative effort under the Unified Command accomplished its goals of cleaning up this spill and protecting our shorelines.

Frank Csulak is scientific support coordinator for the East Coast for NOAA Office of Response and Restoration, covering New York to North Carolina, and acting SSC for northern New England to Long Island Sound. He provides scientific expertise to the U.S. Coast Guard in the case of oil or chemical spills into the marine environment.  This was first published in the NOAA Office of Response and Restoration blog.

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