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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An Oiled River Restored: Salmon Return to Alaskan Stream to Spawn

Last summer NOAA’s Damage Assessment, Remediation, and Restoration Program (DARRP) traveled to the remote Adak Island in Alaska to help salmon return to their historical home by removing barriers from Helmet Creek. We headed back out this September to see how things were going. As you can see from our photos, the salmon seem to be big fans of our 2013 restoration work.

Our mission this September was to monitor the success of these habitat restoration efforts and make sure no new problems have occurred since then. A survey of the creek quickly showed that salmon are now pushing as far upstream as naturally possibly, allowing them to enter formerly impassable areas with ease. Now the only thing preventing salmon from continuing further upstream is a natural waterfall.

During this visit, Helmet Creek was teaming with Pink and Chum salmon. One walk of the roughly two kilometer (one and a quarter mile) portion of stream resulted in our counting more than 600 adult salmon, over half of which were beyond the areas where we had removed fish passage barriers.

Salmon swimming underwater in a creek.

Salmon make their way upstream in Helmet Creek, further than they have been able to access in years thanks to our restoration work. (NOAA)

Before we stepped in to restore Helmet Creek, salmon were hitting a number of man-made obstacles preventing them from getting to the natural areas where they reproduce, known as their spawning grounds. In 2013 we removed these fish barriers, pulling out a number of 55-gallon drums and grates, all of which were impeding the salmon’s ability to swim upstream and covering their spawning grounds.

While seeing all these active fish is exciting, we are also looking forward to the ways these fish will continue helping the environment after they die. As salmon are now able to travel further upstream, they will take valuable nutrients with them too. After spawning, these pink and chum salmon will die and their decaying carcasses will return extremely valuable nutrients to the stream habitat and surrounding area. These nutrients will provide benefits to resident trout, vegetation, and birds nearby.

Restoration of Helmet Creek resulted from our work to restore the environment after a 2010 oil spill on the remote Adak Island, part of Alaska’s Aleutian Island chain. Through DARRP, we worked with our partners to determine how the environment was injured and how best to restore habitat. You can read more about our efforts in—and the unusual challenges of—assessing these environmental impacts to salmon and Helmet Creek.


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Out of Sandy, Lessons in Helping Coastal Marshes Recover from Storms

Cleanup workers scoop oil out of an oiled marsh with containment boom around the edges.

After Sandy’s flooding led to an oil spill at a Motiva refinery, Motiva cleanup workers extract oil from Smith Creek, a waterway connected to the Arthur Kill, in Woodbridge, New Jersey, on November 5, 2012. (NOAA)

Boats capsized in a sea of grass. Tall trees and power lines toppled over. A dark ring of oil rimming marsh grasses. This was the scene greeting NOAA’s Simeon Hahn and Carl Alderson a few days after Sandy’s floodwaters had pulled back from New Jersey in the fall of 2012.

They were surveying the extent of an oil spill in Woodbridge Creek, which is home to a NOAA restoration project and feeds into the Arthur Kill, a waterway separating New Jersey from New York’s Staten Island. When the massive storm known as Sandy passed through the area, its flooding lifted up a large oil storage tank at the Motiva Refinery in Sewaren, New Jersey. After the floodwaters set the tank back down, it caused roughly 336,000 gallons of diesel fuel to leak into the creek and surrounding wetlands.

That day, the NOAA team was there with Motiva and the New Jersey Department of Environmental Protection (DEP) to begin what can be a long and litigious process of determining environmental impacts, damages, and required restoration—the Natural Resource Damage Assessment process.

In this case, however, not only did the group reach a cooperative agreement—in less than six months—on a restoration plan for the oiled wetlands, but at another wetland affected by Sandy, NOAA gained insight into designing restoration projects better able to withstand the next big storm.

Cleaning up the Mess After a Hurricane

Hurricanes and other large storms cause a surprising number of oil and hazardous chemical spills along the coast. After Sandy hit New York and New Jersey, the U.S. Coast Guard began receiving reports of petroleum products, biodiesel, and other chemicals leaking into coastal waters from damaged refineries, breached petroleum storage tanks, and sunken and stranded vessels. The ruptured tank at the Motiva Refinery was just one of several oil spills after the storm, but the approach in the wake of the spill is what set it apart from many other oil spills.

“Early on we decided that we would work together,” reflected Hahn, Regional Resource Coordinator for NOAA’s Office of Response and Restoration. “There was a focus on doing the restoration rather than doing lengthy studies to quantify the injury.”

This approach was possible because Motiva agreed to pursue a cooperative Natural Resource Damage Assessment with New Jersey as the lead and with support from NOAA. This meant, for example, that up front, the company agreed to provide funding for assessing the environmental impacts and implementing the needed restoration, and agreed on and shared the data necessary to determine those impacts. This cooperative process resulted in a timely and cost-effective resolution, which allowed New Jersey and NOAA to transition to the restoration phase.

Reaching Restoration

Because of the early agreement with Motiva, NOAA and New Jersey DEP did not conduct exhaustive new studies detailing specific harm to these particular tidal wetlands. Instead, they turned to the wealth of data from the oil spill response and existing data from the Arthur Kill to make an accurate assessment of the oil’s impacts.

People driving small boats up a marshy river in winter.

A few days after the oil spill, Motiva’s contractors ferried the assessment team up Woodbridge Creek in New Jersey, looking for impacts from the oil. (NOAA)

From their shoreline, aerial, and boat surveys, they knew that the marsh itself had a bathtub ring of oil around the edge, affecting marsh grasses such as Spartina. No oiled wildlife turned up. However, the storm’s immediate impacts made it difficult to take water and sediment samples or directly examine potential effects to fish. Fortunately, the assessment team was able to use a lot of data from a nearby past oil spill and damage assessment in the Arthur Kill. In addition, they could rely on both general scientific research on oil spill toxicology and maps from the response team detailing the areas most heavily oiled.

Together, this created a picture of the environmental injuries the oil spill caused to Woodbridge Creek. Next, NOAA economists used the habitat equivalency analysis approach to calculate the amount of restoration needed to make up for these injuries: 1.23 acres of tidal wetlands. They then extrapolated how much it will cost to do this restoration based on seven restoration projects within a 50 mile radius, coming to $380,000 per acre. As a result, NOAA and New Jersey agreed that Motiva needed to provide $469,000 for saltwater marsh restoration and an additional $100,000 for monitoring, on top of Motiva’s cleanup costs for the spill itself.

To use this relatively small amount of money most efficiently, New Jersey DEP, as the lead agency, is planning to combine it with another, larger restoration project already in the works. While still negotiating which project that will be, the team has been eyeing a high-profile, 80-acre marsh restoration project practically in the shadow of the Statue of Liberty. Meanwhile, the monitoring project will take place upstream from the site of the Motiva oil spill at the 67-acre Woodbridge Creek Marsh, which received light to moderate oiling. NOAA already has data on the state of the animals and plants at this previously established restoration site, which will provide a rare comparison for before and after the oil spill.

Creating More Resilient Coasts

A storm as damaging as Sandy highlights the need for restoring wetlands. These natural buffers offer protection for human infrastructure, absorbing storm surge and shielding shorelines from wind and waves. Yet natural resource managers are still learning how to replicate nature’s designs, especially in urban areas where river channels often have been straightened and adjoining wetlands filled and replaced with shorelines armored by concrete riprap.

To the south in Philadelphia, Sandy contributed to significant erosion at a restored tidal marsh and shoreline at Lardner’s Point Park, located on the Delaware River. This storm revealed that shoreline restoration techniques which dampen wave energy before it hits the shore would help protect restored habitat and reduce erosion and scouring.

Out of this destructive storm, NOAA and our partners are trying to learn as much as possible—both about how to reach the restoration phase even more efficiently and how to make those restoration projects even more resilient. The wide range of coastal threats is not going away, but we at NOAA can help our communities and environment bounce back when they do show up on our shores.

Learn more about coastal resilience and how NOAA’s Ocean Service is helping our coasts and communities bounce back after storms, floods, and other disasters and follow #NOAAResilience on social media.


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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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In Oregon, an Innovative Approach to Building Riverfront Property for Fish and Wildlife

This is a post by Robert Neely of NOAA’s Office of Response Restoration.

Something interesting is happening on the southern tip of Sauvie Island, located on Oregon’s Willamette River, a few miles downstream from the heart of Portland. Construction is once again underway along the river’s edge in an urban area where riverfront property typically is prized as a location for luxury housing, industrial activities, and maritime commerce. But this time, something is different.

This project will not produce a waterfront condominium complex, industrial facility, or marina. And as much as it may look like a typical construction project today, the results of all this activity will look quite different from much of what currently exists along the shores of the lower Willamette River from Portland to the Columbia River.

Indeed, when the dust settles, the site will be transformed into a home and resting place for non-human residents and visitors. Of course, I’m not referring to alien life forms, but rather to the fish, birds, mammals, and other organisms that have existed in and around the Willamette River since long before humans set up home and shop here. Yet in the last century, humans have substantially altered the river and surrounding lands, and high-quality habitat is now a scarce commodity for many stressed critters that require it for their survival.

On the site of a former lumber mill, the Alder Creek Restoration Project is the first habitat restoration project [PDF] that will be implemented specifically to benefit fish and wildlife affected by contamination in the Portland Harbor Superfund Site. The project, managed by a habitat development company called Wildlands, will provide habitat for salmon, lamprey, mink, bald eagle, osprey, and other native fish and wildlife living in Portland Harbor.

Mink at a river's edge.

The Alder Creek Restoration Project will benefit Chinook salmon, mink, and other fish and wildlife living in Portland Harbor. (Roy W. Lowe)

Habitat will be restored by removing buildings and fill from the floodplain, reshaping the riverbanks, and planting native trees and shrubs. The project will create shallow water habitat to provide resting and feeding areas for young salmon and lamprey and foraging for birds. In addition, the construction at Alder Creek will restore beaches and wetlands to provide access to water and food for mink and forests to provide shelter and nesting opportunities for native birds.

Driving this project is a Natural Resource Damage Assessment conducted by the Portland Harbor Natural Resource Trustee Council to quantify natural resource losses resulting from industrial contamination of the river with the toxic compounds PCBs, the pesticide DDT, oil compounds known as PAHs, and other hazardous substances. The services, or benefits from nature, provided by the Alder Creek Restoration Project—such as healthy habitat, clean water, and cultural value—will help make up for the natural resources that were lost over time because of contamination.

Young Chinook salmon on river bottom.

Fish and wildlife species targeted for restoration include salmon (such as the juvenile Chinook salmon pictured here), lamprey, sturgeon, bald eagle, osprey, spotted sandpiper, and mink. (U.S. Fish and Wildlife Service)

Wildlands purchased the land in order to create and implement an early restoration project. This “up-front” approach to restoration allows for earlier implementation of projects that provide restored habitat to injured species sooner, placing those species on a trajectory toward recovery. The service credits—ecological and otherwise—that will be generated by this new habitat will be available for purchase by parties that have liability for the environmental and cultural losses calculated in the damage assessment.

Thus when a party reaches an agreement with the Trustee Council regarding the amount of their liability, they can resolve it by purchasing restoration credits from Wildlands. And Wildlands, as the seller of restoration credits, recoups the financial investment it made to build the project. Finally, and most importantly, a substantial piece of land with tremendous potential value for the fish, birds, and other wildlife of the lower Willamette River has been locked in as high-quality habitat and thus protected from future development for other, less ecologically friendly purposes.

Robert NeelyRobert Neely is an environmental scientist with the National Oceanic and Atmospheric Administration’s Office of Response and Restoration. He has experience in ocean and coastal management, brownfields revitalization, Ecological Risk Assessment, and Natural Resource Damage Assessment. He started with NOAA in 1998 and has worked for the agency in Charleston, South Carolina; Washington, DC; New Bedford, Massachusetts; and Seattle, Washington, where he lives with his wife and daughter. He’s been working with his co-trustees at Portland Harbor since 2005.


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Two Unlikely Neighbors, Orphans and Industry, Share a Past Along the Delaware River

Sign in a grassy field, in front of an old brick building.

An EPA sign marking the Metal Bank Superfund Site stands near the old St. Vincent’s Orphanage building. (EPA)

When NOAA environmental scientist Alyce Fritz talks about her first visit to the Metal Bank Superfund Site back in 1986, she always mentions the orphanage next door. St. Vincent’s Orphans Asylum, as it was named when it was opened by the Catholic Archdiocese of Philadelphia in 1857, is separated from the Metal Bank site by a stormwater outfall that drains into the Delaware River just north of the former orphanage.

The Metal Bank Superfund Site and St. Vincent’s are located several miles north of the center of Philadelphia, Pennsylvania, on the banks of the Delaware River in an industrial district that is part of the historic Tacony neighborhood. Located on 29 acres along the river, St. Vincent’s looks like a beautiful old park. What Fritz remembers clearly on that first visit was the children’s playground equipment placed near the river’s edge.

Large brick building with St. Vincint's over the door.

St. Vincent’s, as it appears today on the Delaware River in the Tacony neighborhood of Philadelphia.

On the adjacent 10 acre Metal Bank site, a company called Metal Bank of America, Inc., owned and operated a salvage facility where scrap metal and electric transformers were recycled for over 60 years. Part of the recycling process used by Metal Bank of America, Inc. involved draining oil—loaded with toxic compounds including PCBs—from the used transformers to reclaim copper parts. PCBs are considered a probable cause of cancer in humans and are harmful to clams and fish found in the mudflats and river next to the site.

In the 1970s the U.S. Coast Guard discovered oil releases in the Delaware River and traced them back to the site. Throughout the 1980s, the Metal Bank site’s owners used an oil recovery system to clear the groundwater of PCB-laced oil. However, oil continued to seep from an underground tank at the site. As a result, PCBs and other hazardous substances were left in the soil, groundwater, and river bed sediments at the Metal Bank site and adjacent to St. Vincent’s.

In 1983 the Metal Bank site was placed on the National Priorities List (the Superfund program) and slated for federal cleanup. During the course of the federal cleanup process, various parties were identified as being liable for the contamination at the site, including a number of utility companies that transported their used electrical transformers to the Metal Bank site for disposal or otherwise arranged to dispose of their used electrical transformers at the Metal Bank site.

Federal and local agencies collaborated on a design for cleanup of multiple contaminants of concern at the Metal Bank site. Found in the soil, sediment, groundwater, and surface water, these contaminants included but were not limited to:

  • PCBs.
  • polynuclear aromatic hydrocarbons (a toxic component of oil).
  • semi-volatile organic compounds.
  • pesticides.
  • metals.

The cleanup, which began in 2008, included excavating soils and river sediments contaminated with PCBs, capping some areas of river sediment, installing a retaining wall near the river, and removing an old transformer oil storage tank. Most of this work was completed in 2010.

Panorama of Metal Bank Superfund Site from the top of steps by the river to the mudflats in 1991. The view is looking south on the Delaware River past St. Vincent’s property. (NOAA) A view of the outflow where water runs into the Delaware River to the south of the Metal Bank site in 2013. (NOAA) A riprap sampling station near an oil slick in 1993 in front of the Metal Bank site. (NOAA) A view of the Delaware River across the mudflats on the Metal Bank Site. (EPA)

Panorama of Metal Bank Superfund Site from the top of steps by the river to the mudflats in 1991. The view is looking south on the Delaware River past St. Vincent’s property. (NOAA) A view of the outflow where water runs into the Delaware River to the south of the Metal Bank site in 2013. (NOAA) A riprap sampling station near an oil slick in 1993 in front of the Metal Bank site. (NOAA) A view of the Delaware River across the mudflats on the Metal Bank Site. (EPA)

As part of the required 5-year review period, monitoring of the Metal Bank site continues. This is to ensure the cleanup is still protecting human health and the environment, including endangered Atlantic Sturgeon and Shortnose Sturgeon. Through successful coordination among the EPA, other federal and state agencies, and some of the potentially responsible parties (PRPs) during the Superfund process, the cleanup has reduced the threat to natural resources in the river and enhanced the recovery of the habitat along the site and St. Vincent’s property.

Over the years, the role of St. Vincent’s has evolved too, from serving as a long-term home for orphans toward one of providing short-term shelter and care to abused and neglected children. Prior to the early 1990s, children who came to St. Vincent’s spent a significant part of their childhood as residents of the institution. In a 1992 article in the Philadelphia Daily News, Sister Kathleen Reilly explained that the children currently cared for by St. Vincent’s range in age from two to 12 years of age and are placed at the home temporarily through an arrangement between the City of Philadelphia Department of Human Services and Catholic Social Services. Today St. Vincent’s serves young people mostly through day programs. One thing hasn’t changed though—the lush grounds along the river are still beautiful.

Playground swings at St. Vincent's. Statue of St. Vincent with a child in front of large brick building. Elaborate locked iron gate with a cross. Pavilion with trees and river view.

From top left: A recent photo of part of the play area behind St. Vincent’s on the grounds facing the Delaware River. (NOAA) An old photo of a statue in front of St. Vincent’s Orphan Asylum, as it was originally named. (U.S. Library of Congress) The main building of the historic institution in Northeast Philadelphia that first opened its gates in 1857 as St. Vincent’s Orphans Asylum. Photo was taken in 2013. (NOAA) An old photo of a pavilion in the recreational area behind St. Vincent’s main building. The Delaware River and playground equipment is visible in the background. (U.S. Library of Congress)

The federal and state co-trustees for the ongoing Natural Resource Damage Assessment at the Metal Bank site include NOAA’s Damage Assessment, Remediation, and Restoration Program; the U.S. Fish and Wildlife Service; and multiple Pennsylvania state agencies. Collectively, the trustees are working together to further engage with the potentially responsible parties and build upon what has been accomplished at the site by the cleanup.

The trustees have invited the potentially responsible parties to join them in a cooperative effort to improve habitat for the injured natural resources (such as habitat along the river and wetlands) that support the clams, fish, and birds using the Delaware River. In addition, there is the potential for a trail to be routed through the property to a scenic view of St. Vincent’s and the river (an area which is now safe for recreational use). The trustees hope that the natural resources at the Metal Bank site can evolve to become a vibrant part of the historic Tacony neighborhood once again too.


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As Oil Sands Production Rises, What Should We Expect at Diluted Bitumen (Dilbit) Spills?

Pipeline dug up for an oil spill cleanup next to a creek.

This area is where the Enbridge pipeline leaked nearly a million gallons of diluted bitumen (dilbit), a tar sands oil product, into wetlands, Talmadge Creek, and roughly 40 miles of Michigan’s Kalamazoo River in 2010. (U.S. Environmental Protection Agency)

I’ve seen a lot of firsts in the past four years.

During that time, I have been investigating the environmental impacts, through the Natural Resource Damage Assessment process, of the Enbridge pipeline spill in Michigan. In late summer of 2010, a break in an underground pipeline spilled approximately 1 million gallons of diluted bitumen into a wetland, a creek, and the Kalamazoo River. Diluted bitumen (“dilbit”) is thick, heavy crude oil from the Alberta tar sands (also known as oil sands), which is mixed with a thinner type of oil (the diluent) to allow it to flow through a pipeline.

A Whole New Experience

This was my first and NOAA’s first major experience with damage assessment for a dilbit spill, and was also a first for nearly everyone working on the cleanup and damage assessment. Dilbit production and shipping is increasing. As a result, NOAA and our colleagues in the field of spill response and damage assessment are interested in learning more about dilbit:

  • How does it behave when spilled into rivers or the ocean?
  • What kinds of effects does it have on animals, plants, and habitats?
  • Is it similar to other types of oil we’re more familiar with, or does it have unique properties?

While it’s just one case study, the Enbridge oil spill can help us answer some of those questions. My NOAA colleague Robert Haddad and I recently presented a scientific paper on this case study at Environment Canada’s Arctic and Marine Oil Spill Program conference.

In addition, the Canadian government and oil pipeline industry researchers Witt O’Brien’s, Polaris, and Western Canada Marine Response Corporation [PDF] and SL Ross [PDF] have been studying dilbit behavior as background research related to several proposed dilbit pipeline projects in the United States and Canada. Those experiments, along with the Enbridge spill case study, currently make up the state of the science on dilbit behavior and ecological impacts.

How Is Diluted Bitumen Different from Other Heavy Oils?

Dilbit is in the range of other dense, heavy oils, with a density of 920 to 940 kg/m3, which is close to the density of freshwater (1,000 kg/m3). (In general when something is denser than water, it will sink. If it is less dense, it will float.) Many experts have analyzed the behavior of heavy oils in the environment and observed that if oil sinks below the surface of the water, it becomes much harder to detect and recover. One example of how difficult this can be comes from a barge spill in the Gulf of Mexico, which left thick oil coating the bottom of the ocean.

What makes dilbit different from many other heavy oils, though, is that it includes diluent. Dilbit is composed of about 70 percent bitumen, consisting of very large, heavy molecules, and 30 percent diluent, consisting of very small, light molecules, which can evaporate much more easily than heavy ones. Other heavy oils typically have almost no light components at all. Therefore, we would expect evaporation to occur differently for dilbit compared to other heavy oils.

Environment Canada confirmed this to be the case. About four to five times as much of the dilbits evaporated compared to intermediate fuel oil (a heavy oil with no diluent), and the evaporation occurred much faster for dilbit than for intermediate fuel oil in their study. Evaporation transports toxic components of the dilbit into the air, creating a short-term exposure hazard for spill responders and assessment scientists at the site of the spill, which was the case at the 2010 Enbridge spill.

Graph of evaporation rates over time of two diluted bitumen oils and another heavy oil.

An Environment Canada study found that two types of diluted bitumen (dilbits), Access Western Blend (AWB) and Cold Lake Blend (CLB), evaporated more quickly and to a greater extent than intermediate fuel oil (IFO). The two dilbits are shown on the left and the conventional heavy oil, IFO, on the right. (Environment Canada)

Since the light molecules evaporate after dilbit spills, the leftover residue is even denser than what was spilled initially. Environment Canada, Witt O’Brien’s/Polaris/WCMRC, and SL Ross measured the increase in dilbit density over time as it weathered, finding dilbit density increased over time and eventually reached approximately the same density as freshwater.

These studies also found most of the increase in density takes place in the first day or two. What this tells us is that the early hours and days of a dilbit spill are extremely important, and there is only a short window of time before the oil becomes heavier and may become harder to clean up as it sinks below the water surface.

Unfortunately, there can be substantial confusion in the early hours and days of a spill. Was the spilled material dilbit or conventional heavy crude oil? Universal definitions do not exist for these oil product categories. Different entities sometimes categorize the same products differently. Because of these discrepancies, spill responders and scientists evaluating environmental impacts may get conflicting or hard-to-interpret information in the first few days following a spill.

Lessons from the Enbridge Oil Spill

Initially at the Enbridge oil spill, responders used traditional methods to clean up oil floating on the river’s surface, such as booms, skimmers, and vacuum equipment (see statistics on recovered oil in EPA’s Situation Reports [PDF]).

After responders discovered the dilbit had sunk to the sediment at the river’s bottom, they developed a variety of tactics to collect the oil: spraying the sediments with water, dragging chains through the sediments, agitating sediments by hand with a rake, and driving back and forth with a tracked vehicle to stir up the sediments and release oil trapped in the mud.

These tactics resulted in submerged oil working its way back up to the water surface, where it could then be collected using sorbent materials to mop up the oily sheen.

While these tactics removed some oil from the environment, they might also cause collateral damage, so the Natural Resource Damage Assessment trustees assessed impacts from the cleanup tactics as well as from the oil itself. This case is still ongoing, and trustees’ assessment of those impacts will be described in a Damage Assessment and Restoration Plan after the assessment is complete.

A hand holds a crushed mussel.

A freshwater mussel found crushed in an area of the Kalamazoo River with heavy cleanup traffic following the 2010 Enbridge oil spill. (Enbridge Natural Resource Damage Assessment Trustee Council)

For now, we can learn from the Enbridge spill and help predict some potential environmental impacts of future dilbit spills. We can predict that dilbit will weather (undergo physical and chemical changes) rapidly, becoming very dense and possibly sinking in a matter of days. If the dilbit reaches the sediment bed, it can be very difficult to get it out, and bringing in responders and heavy equipment to recover the oil from the sediments can injure the plants and animals living there.

To plan the cleanup and response and predict the impacts of future dilbit spills, we need more information on dilbit toxicity and on how quickly plants and animals can recover from disturbance. Knowing this information will help us balance the potential impacts of cleanup with the short- and long-term effects of leaving the sunken dilbit in place.


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A River Reborn: Restoring Salmon Habitat along Seattle’s Duwamish River

Industrial river with part of a boat in the view.

Cutting through south Seattle, the Duwamish River is still very much an industrial river. (NOAA)

Just south of Seattle, the airplane manufacturer Boeing Company has created one of the largest habitat restoration projects on the Lower Duwamish River. Boeing worked with NOAA and our partners under a Natural Resource Damage Assessment to restore habitat for fish, shorebirds, and wildlife harmed by historical industrial activities on this heavily used urban river. We documented and celebrated this work in a short video.

What Kind of Restoration?

In this video, you can learn about the restoration techniques used in the project and how they will benefit the communities of people, fish, and wildlife of the Duwamish River. The restoration project included activities such as:

  • Reshaping the shoreline and adding 170,000 native plants and large woody debris, which provide areas where young salmon can seek refuge from predators in the river.
  • Creating 2 acres of wetlands to create a resting area for migrating salmon.
  • Transforming more than a half mile of former industrial waterfront back into natural shoreline.

Watch the video:

Why Does this River Need Restoring?

In 1913, the U.S. Army Corps of Engineers excavated and straightened the Duwamish River to expand Seattle’s commercial navigation, removing more than 20 million cubic yards of mud and sand and opening the area to heavy industry. But development on this waterway stretches back to the 1870s.

Ninety-seven percent of the original habitat for salmon—including marsh, mudflats, and toppled trees along multiple meandering channels— was lost when they transformed a 9-mile estuary into a 5-mile industrial channel.

As damaged and polluted as the Lower Duwamish Waterway is today, the habitat here is crucial to ensuring the survival and recovery of threatened fish species, including the Puget Sound Chinook and Puget Sound Steelhead. These young fish have to spend time in this part of the Duwamish River, which is a Superfund Site, as they transition from the river’s freshwater to the saltwater of the Puget Sound and Pacific Ocean. Creating more welcoming habitat for these fish gives them places to find food and escape from predators.

Fortunately, this restored waterfront outside of a former Boeing plant will be maintained for all time, and further cleanup and restoration of the river is in various stages as well.

UPDATE 6/17/2014: On June 17, 2014, Boeing hosted a celebration on the newly restored banks of the Lower Duwamish River to recognize the partners who helped make the restoration a reality. Speakers at the event included NOAA, Boeing, the Muckleshoot Tribe, and a local community group. This also gave us the opportunity to share the video “A River Reborn,” which was well received.

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