NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution


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A Final Farewell to Oil Tankers with Single Hulls

January 1, 2015 marks a major milestone in preventing oil spills. That date is the deadline which the landmark Oil Pollution Act of 1990 (OPA-90) specifies for phasing out single-hull tankers in U.S. waters. That act, passed after the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, required that all new tankers and tank-barges be built with double hulls.

Recently constructed single-hull tankers were allowed to operate, but 25 years after the Exxon Valdez, those vessels are now at the end of their operational life and will no longer be able to carry oil as cargo. The requirement was phased in gradually because of the difficultly of converting existing single-hull tankers to double hulls, and retiring the single-hull tankers more rapidly would have been a major disruption to world shipping.

Counting Down to a New Era

There won’t be a dramatic change-over on New Year’s Eve; most of the tankers calling on U.S. ports have had double hulls years before this deadline. However, one ship which was not switched over to a double hull soon enough was the tanker Athos I. This ship, carrying 13.6 million gallons of heavy crude oil, struck a submerged anchor in the Delaware River and caused a relatively large, complicated oil spill near Philadelphia, Pennsylvania, 10 year ago.

In 1992, two years after the Oil Pollution Act, the International Convention for the Prevention of Pollution from Ships (the MARPOL Convention) was amended to require all newly built tankers have double hulls. MARPOL has been ratified by 150 countries, representing over 99 percent of merchant tonnage shipped worldwide.

Stay out of Trouble by Going Double

So, what is the big issue around single vs. double-hull ships? Historically, tankers carrying oil were built with a single hull, or single shell.

While we measure oil in barrels, it is not actually shipped that way. Instead, oil is pumped into huge tanks that are part of the structure of tankers and barges. For vessels with a single hull, one plate of steel is all that separates the oil on board from the ocean. If the hull were punctured from a collision or grounding, an oil spill is pretty much guaranteed to follow. On the other hand, a ship with a double hull has two plates of steel with empty space in between them. The second hull creates a buffer zone between the ocean and the cargo of oil.

Naval architects have debated the merits of various hull designs in reducing oil spills, and using a double hull, essentially a hull within a hull, was selected as the preferred vessel design.

Close up of gash in hull on Cosco Busan cargo ship.

The cargo ship Cosco Busan lost 53,000 gallons of fuel oil when the single-hull ship hit the San Francisco-Oakland Bay Bridge in 2007. (U.S. Coast Guard)

However, the double hull requirements only apply to tankers and tank barges. Container ships, freighters, cruise ships, and other types of vessels are still built with single hulls. While these ships carry a lot less oil than a tanker, a large non-tank vessel can still carry a lot of fuel oil, and some have caused some pretty big spills, including the 2007 oil spill caused by the cargo ship Cosco Busan in San Francisco Bay.

Of course, double hulls don’t prevent all oil spills from tankers either, but the design has been credited with reducing the amount spilled, especially in the cases of low-speed groundings and collisions.

And some pretty spectacular collisions have resulted in double-hull tankers not spilling a drop.

Twenty years after the Exxon Valdez oil spill, the Norwegian tanker SKS Satilla collided with a submerged oil rig in the Gulf of Mexico. The collision tore a huge hole in the side of the oil tanker, but, thankfully, none of the 41 million gallons of crude oil it had on board was spilled.


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Before Breaking Ground for Restoration, Digging for Signs of the Past

This is a post by Carl Alderson of NOAA’s Restoration Center.

Birds flying over a flooded field with a nuclear power plant in the distance.

Glossy Ibis flocking to an accidental wet meadow, left by the farmer’s plow in early spring 2003 at Mad Horse Creek. Salem Nuclear Power Plant in the distance. (NOAA)

Looking across the open fields of the surrounding farm community, I am reminded of the long history of both European and Native American settlement in this portion of southwest New Jersey. Before Europeans arrived in the 17th century, this area was part of Lenape Indian territory.

Today, however, it is the site of a future restoration project at Mad Horse Creek Fish and Wildlife Management Area.

In partnership with the State of New Jersey, I’m involved in an effort to restore nearly 200 acres of degraded marshland, wet meadow, and grassland in this part of Salem County.

The restored habitat will provide food as well as roosting and nesting habitat for birds. This is one of many projects NOAA and our partners have developed as part of the restoration plan in the wake of the 2004 Athos I oil spill, which killed nearly 12,000 birds along the nearby Delaware River.

The Artifacts of Nature

Numerous historical artifacts have been uncovered on lands surrounding Mad Horse Creek, so it’s important that before we begin restoring the natural habitat, we make sure we are preserving any colonial or Native American artifacts that might be hidden beneath these fields.

I’ve been working with Vincent Maresca, a Senior Historic Preservation Specialist with the State of New Jersey to develop plans for a Phase I archaeological investigation of the area. Using a disk cultivator (a machine typically used to cultivate soil between rows of plants), we will be disking all 200 acres of the restoration site, turning over the soil at a depth of 18 inches.

Once we get a rainstorm, we can expect any artifacts in the soil to be revealed. At that point, it will take a team of 12 people two weeks to walk the site, one person to a row, looking for exposed shards of pottery or other objects. Anything we find will be placed into collection bags and identified with the GPS location.

If we find historical artifacts at the Mad Horse Creek restoration area, we will begin a Phase II archaeological investigation. This likely would involve digging more extensive excavation pits in the immediate area of each find to uncover other potential artifacts.

The people who do this work are known as field archaeologists. They typically have a degree in anthropology or archaeology and receive specialized training in testing and excavating archaeological sites; screening the soil for evidence; washing, bagging, and labeling artifacts; and completing field inventories of their findings.

When Restoration Meets Preservation

No restoration work will begin until we complete this archaeological search. At all times, NOAA makes sure to consult with historic preservationists on each of our sites in accordance with the National Historic Preservation Act.

In the first part of the process we ask for input from state experts like Vincent Maresca. Those experts determine whether we should do an archaeological evaluation of the site based on the likelihood of finding artifacts, as was the case at Mad Horse Creek. If the likelihood is high, we then seek input from the federal agency known as the Advisory Council on Historic Preservation.

I don’t know what we’re going to find at Mad Horse Creek, if anything, but as we near Thanksgiving, I am particularly thankful to be working on a project that is working to restore and preserve both our natural and cultural treasures.


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After Opening up a Pennsylvania Creek for Fish, Watching Recovery Follow

This is a guest post by Laura Craig, Ph.D., Associate Director of River Restoration, American Rivers.

Excavator removes a rock dam from a stream.

Restoring Darby Creek, a tributary of the Delaware River, meant tearing down three now-defunct mill dams. Here, the Hoffman Park dam at Lansdowne, Pennsylvania, comes down. (American Rivers)

Early settlement along Pennsylvania’s Darby Creek relied upon dams to turn the water wheels of mills, powering economic growth. However, as time wore on, the dams on this tributary of the Delaware River fell into disrepair and these days no longer serve a function. Instead, they have been blocking the passage of fish along this creek. That is, until now.

In late summer of 2012, American Rivers and our project partners, NOAA’s Damage Assessment, Remediation, and Restoration Program  and the Pennsylvania Fish and Boat Commission, began tearing down some of those now-defunct dams as part of a multi-year effort to restore Darby Creek. Initiated in 2007, the effort involved removing three dams near Philadelphia: Darby Borough Dam, Hoffman Park Dam, and Kent Park Dam. In addition, we took out a set of abandoned railroad piers and realigned an 800 foot section of the creek.

We removed these barriers to improve passage for a range of resident and migratory fish, including American shad, hickory shad, alewife, river herring, American eel, bass, shiners, and suckers. The project also aims to enhance stream habitat, alleviate flooding, benefit public safety, and restore free-flowing conditions along the creek.

Green plants growing along a stream.

Shown in 2014, this portion of Darby Creek now features restored shoreline habitat with stabilizing structures. (American Rivers)

Overall, the Darby Creek Restoration Project connected 2.6 miles of upper stream to the lower 9.7 miles, which link directly to the Delaware River. It was here in 2004 when the Athos I tanker spilled oil that would spread along miles of the Delaware and its tributaries similar to Darby Creek.

This $1.6 million dollar effort to restore Darby Creek was funded primarily by the Natural Resource Damage Assessment settlement from the Athos I oil spill. Additional funding came from the Pennsylvania Department of Environmental Protection’s Growing Greener Program and the National Fish and Wildlife Foundation. All restoration activities were completed in June 2013, but we are still monitoring the restored areas to ensure the area is recovering.

At the former dam locations we are already seeing recovery of shoreline areas planted with a diverse mix of seed, shrubs, and trees. Restoring vegetation along the creek stabilizes exposed soil and reduces erosion in the short term and provides shade, habitat, and food sources over the long term. We are also observing positive changes to stream habitat as a result, including fewer actively eroding banks and less fine sediment clouding the creek’s waters.

In terms of fisheries, we are noting a shift since the dams were removed toward a resident community of fish that prefer free-flowing water conditions. While we haven’t yet encountered any migratory fish at the former dam locations, this fall fisheries biologists with the Pennsylvania Fish and Boat Commission came across several pods of very young blueback herring in the tidal portion of the creek, near where it joins the Delaware River at the John Heinz National Wildlife Refuge. This is great news, because it suggests that blueback herring are using the lower part of the tributary as a nursery. In future years we hope to see them advance up the creek to the locations where the dams were removed.

For more information on the Athos I oil spill and the resulting restoration, visit response.restoration.noaa.gov/athos and http://www.darrp.noaa.gov/northeast/athos/restore.html.


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When the Dynamics of an Oil Spill Shut Down a Nuclear Power Plant

Yellow containment boom floats on a river next to a nuclear power plant.

Precautionary containment boom is visible around the water intake system at the Salem Nuclear Generating Station in New Jersey on December 6, 2004. The nuclear plant was shut down for 11 days to prevent the heavy, submerged oil from the Athos spill from clogging the water intakes. (NOAA)

“I’ve never reopened a nuclear power plant,” thought NOAA’s Ed Levine. Despite that, Levine knew it was his job to get the right information to the people who ultimately would make that decision. This was his role as a NOAA Scientific Support Coordinator during oil spills. However, most major oil spills do not affect nuclear power plants. This wintry day in 2004 was an exception.

Forty miles north of the Salem Nuclear Generating Station in New Jersey, an oil tanker called the Athos I had struck an object hidden beneath the Delaware River. As it was preparing to dock at the CITGO refinery near Philadelphia on November 26, the ship began tilting to one side, the engine shut down, and oil started gushing out.

“Not your typical oil spill,” later reflected Jonathan Sarubbi, who served as U.S. Coast Guard Captain of the Port and led the federal response during this incident. Not only did no one immediately know what the ship had hit—or where that object was located in the river channel—but the Athos, now sitting too low in the water to reach the dock, was stuck where it was. And it was still leaking its cargo of heavy Venezuelan crude oil.

Capt. Sarubbi ordered vessel traffic through this busy East Coast shipping channel to stop until the object the Athos hit could be found. Little did Capt. Sarubbi, Levine, and the other responders know that even more challenges would be in store beneath the water and down the river.

Getting Mixed up

Most oils, most of the time, float on the surface of water. This was precisely what responders expected the oil coming out of the Athos to do. But within a couple days of the spill, they realized that was not the case. This oil was a little on the heavier side. As it shot out of the ship’s punctured bottom, some of the oil mixed with sediment from the river bottom. It didn’t have far to go; thanks to an extremely low tide pulling the river out to sea, the Athos was passing a mere 18 inches above the bottom of the river when it sprung a leak.

Now mixed with sediment, some of the spilled oil became as dense as or denser than water. Instead of rising to the river surface, it sank to the bottom or drifted in the water column. Even some of the oil that floated became mixed with sediment along the shoreline, later sinking below the surface. For the oil suspended in the water, the turbulence of the Delaware River kept it moving with the currents increasingly toward the Salem nuclear plant, perched on the river’s edge.

NOAA’s oil spill trajectory model GNOME forecasts the spread of oil by assuming the oil is floating on the water’s surface. Normally, our oceanographers can verify how well the forecasts are doing by calibrating the model against twice-a-day aerial surveys of the oil’s movement. The trouble with oil that does not float is that it is harder to see, especially in the murky waters of the Delaware River.

Responders were forced to improvise. To track oil underwater, they created new sampling methods, one of which involved dropping weighted ropes into the water column at various points along the river. The ropes were lined with what looked like cheerleader pom-poms made of oil-attracting plastic strips that would pick up oil as it passed by.

Nuclear Ambitions

Nuclear plants like the Salem facility rely on a steady flow of freshwater to cool their reactors. A thin layer of floating oil was nearing the plant by December 1, 2004, with predictions that the heavier, submerged oil would not be far behind. By December 3, small, sticky bits of oil began showing up in the screens on the plant’s cooling water intakes. To keep them from becoming clogged, the plant decided to shut down its two nuclear reactors the next day. That was when NOAA’s Ed Levine was tasked with figuring out when the significant threats due to the oil had passed.

Eleven days later, the Salem nuclear plant operators, the State of New Jersey, and the Nuclear Regulatory Commission allowed the plant to restart. A combination of our modeling and new sampling methods for detecting underwater oil had shown a clear and significant drop in the amount of oil around the plant. Closing this major electric generating facility cost $33.1 million out of more than $162 million in claims paid to parties affected by the Athos spill. But through our innovative modeling and sampling, we were able to reduce the time the plant was offline, minimizing the disruption to the power grid and reducing the economic loss.

Levine recalled this as an “eye-opening” experience, one yielding a number of lessons for working with nuclear power plants should an oil spill threaten one in the future. To learn more about the Athos oil spill, from response to restoration, visit response.restoration.noaa.gov/athos.

A special thanks to NOAA’s Ed Levine and Chris Barker, former U.S. Coast Guard Captain Jonathan Sarubbi, and Henry Font, Donna Hellberg, and Thomas Morrison of the Coast Guard National Pollution Funds Center for sharing information and data which contributed to this post.


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Protecting, Restoring, and Celebrating Estuaries—Where Salt and Freshwater Meet

Collage: lighthouse, kids viewing wildlife, heron, canoe in water, flowers, and meandering wetlands.

Estuaries are ecosystems along the oceans or Great Lakes where freshwater and saltwater mix to create wetlands, bays, lagoons, sounds, or sloughs. (NOAA’s National Estuarine Research Reserves)

As the light, fresh waters of rivers rush into the salty waters of the sea, some incredible things can happen. As these two types of waters meet and mix, creating habitats known as estuaries, they also circulate nutrients, sediments, and oxygen. This mixing creates fertile waters for an array of life, from mangroves and salt-tolerant marsh grasses to oysters, salmon, and migrating birds. These productive areas also attract humans, who bring fishing, industry, and shipping along with them.

All of this activity along estuaries means they are often the site of oil spills and chemical releases. We at NOAA’s Office of Response and Restoration often find ourselves working in estuaries, trying to minimize the impacts of oil spills and hazardous waste sites on these important habitats.

A Time to Celebrate Where Rivers Meet the Sea

September 20–27, 2014 is National Estuaries Week. This year 11 states and the District of Columbia have published a proclamation recognizing the importance of estuaries. To celebrate these critical habitats, Restore America’s Estuaries member organizations, NOAA’s National Estuarine Research Reserve System, and EPA’s National Estuary Program are organizing special events such as beach cleanups, hikes, canoe and kayak trips, cruises, and workshops across the nation. Find an Estuary Week event near you.

You and your family and friends can take a personal stake in looking out for the health and well-being of estuaries by doing these simple things to protect these fragile ecosystems.

How We Are Protecting and Restoring Estuaries

You may be scratching your head wondering whether you know of any estuaries, but you don’t need to go far to find some famous estuaries. The Chesapeake Bay and Delaware Bay are on the east coast, the Mississippi River Delta in the Gulf of Mexico, and San Francisco Bay and Washington’s Puget Sound represent some notable estuarine ecosystems on the west coast. Take a closer look at some of our work on marine pollution in these important estuaries.

Chesapeake Bay: NOAA has been working with the U.S. Environmental Protection Agency and Department of Defense on cleaning up and restoring a number of contaminated military facilities around the Chesapeake Bay. Because these Superfund sites are on federal property, we have to take a slightly different approach than usual and are trying to work restoration principles into the cleanup process as early as possible.

Delaware Bay: Our office has responded to a number of oil spills in and adjacent to Delaware Bay, including the Athos oil spill on the Delaware River in 2004. As a result, we are working on implementing several restoration projects around the Delaware Bay, which range from creating oyster reefs to restoring marshes, meadows, and grasslands.

Puget Sound: For Commencement Bay, many of the waterways leading into it—which provide habitat for salmon, steelhead, and other fish—have been polluted by industrial and commercial activities in this harbor for Tacoma, Washington. NOAA and other federal, state, and tribal partners have been working for decades to address the contamination and restore damaged habitat, which involves taking an innovative approach to maintaining restoration sites in the Bay.

Further north in Puget Sound, NOAA and our partners have worked with the airplane manufacturer Boeing to restore habitat for fish, shorebirds, and wildlife harmed by historical industrial activities on the Lower Duwamish River, a heavily used urban river in Seattle. Young Puget Sound Chinook salmon and Steelhead have to spend time in this part of the river, which is a Superfund Site, as they transition from the river’s freshwater to the saltwater of the Puget Sound. Creating more welcoming habitat for these fish gives them places to find food and escape from predators.

San Francisco Bay: In 2007 the M/V Cosco Busan crashed into the Bay Bridge and spilled 53,000 gallons of thick fuel oil into California’s San Francisco Bay. Our response staff conducted aerial surveys of the oil, modeled the path of the spill, and assessed the impacts to the shoreline. Working with our partners, we also evaluated the impacts to fish, wildlife, and habitats, and determined the amount of restoration needed to make up for the oil spill. Today we are using special buoys to plant eelgrass in the Bay as one of the spill’s restoration projects


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Oil Spills and the Holidays, Act II: Black Friday Takes a New Meaning

In the last post, Doug Helton talked about the M/V Kuroshima spill in Alaska. The next Thanksgiving story comes to us from Ed Levine, the NOAA Scientific Support Coordinator for Connecticut to Delaware.

After a wonderful family Thanksgiving seven years ago, what we in the response business refer to as the “Usual Notification”—a call in the middle of the night during a long holiday weekend—came true. At 9:30 p.m. on November 26, 2004, the (Black) Friday after Thanksgiving, the tanker Athos I was damaged while docking at the CITGO refinery on the Delaware River and began spilling its cargo of Venezuelan crude oil. By 2:00 a.m., I was requested to go on-scene and support the Coast Guard’s response in Philadelphia.

My sons and wife were used to this scrambling to pack and run out the door. Little did we know how complicated this response would be and how long it would last!

When I arrived, prior to first light, many details were still unknown or just unfolding. We knew the ship was leaking oil, it was leaning to one side, but it was secure at anchor. At that time we didn’t know how much oil was leaking, where it was going, how far it would spread, the cause of the damage, the environmental and economic impacts it would have, or the duration of the clean up.

Athos I

Tanker Athos I anchored in the Delaware River. Credit: Ed Levine, NOAA.

At daylight, the first helicopter surveys found some oil along the Pennsylvania shoreline, but the first reports were not too alarming. But I knew it was important to get some calibrated eyes on the spill, someone with experience spotting oil from the air. It’s not as easy as it sounds to conduct an aerial survey.

After a few hours in the command post, I had a chance to fly.

During my overflight (aerial survey), it was clear that the ship was still leaking. I observed oil many miles up river and in larger concentrations than previously reported. Upon returning to the command post, I told the Captain of the Port, “we need a bigger boat!” This was a major oil spill, and we were going to be here a long time cleaning it up.

Little did I know how right I was.

Oiled Diver

Commercial diver covered in oil after a bottom survey. Credit: U.S. Coast Guard.

The ship’s crew was eventually able to transfer cargo around the tanks to stop the outflow of oil, but over 240,000 gallons of heavy crude oil were released from the ship. The cleanup took a full year until all the shorelines were signed off as clean. A nuclear power plant even shut down for over a week. Vessel traffic into the port stopped for eight days until the mysterious object that the vessel struck could be located. Hundreds of birds were oiled. Hundreds of miles of shoreline in three states had to be inspected and the oiled areas cleaned up.

Winter operations became brutal, the river eventually froze over and operations ceased for a couple months. In the early weeks of the response, a boat overturned with five people on board. Luckily for them a NOAA ship was nearby and able to rescue all of them.

Shoreline clean up

Shoreline clean up, Tinicum Island, Delaware River. Credit: Ed Levine, NOAA.

The spilled oil was nearly neutrally buoyant in the brackish waters of the Delaware Estuary, meaning the oil was just as likely to sink as it was to float, complicating cleanup operations. Eventually, the shorelines were cleaned, and damages to natural resources were assessed and restored [leaves this blog].

Because of this accident, the response community has become more prepared and new legislation was passed (President Signs Oil Spill Legislation) [leaves this blog]. It was historic at the time, and I was glad I had given a little piece to the success of the response. It’s a thought that helps me be prepared for the next “Usual Notification” I will receive, whenever it comes.

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