Superfund Sites and the Floods of Hurricane Harvey: Foreseeable or an “Act of God"?

September 6, 2017 | 4:33 pm
Patrick Bloodgood/US Army
Jacob Carter
Research Director

Superfund sites contain some of the most dangerous chemicals known to humankind. It has been confirmed that Superfund sites in the Houston area were submerged by the floodwaters of Hurricane Harvey. Does this mean these hazardous chemicals were swept away off of Superfund sites into neighboring communities where people live, play, and work? If so, who will be responsible for cleaning up such a disaster?

There are approximately a dozen Superfund sites in the Houston area that could have been compromised by floodwaters. The Associated Press surveyed seven of these sites and found signs of inundation, and the Environmental Protection Agency (EPA) has reported that 13 of 41 Superfund sites in the area were flooded, using aerial images. Nancy Loeb, director of the Environmental Advocacy Center at Northwestern University’s Pritzker School of Law, cautioned that “If the water picks up contaminated sediment from [Superfund] sites, that may get deposited in areas where people frequent—residential properties, parks, ballfields—that were never contaminated before. We can’t say for sure it will happen, but it’s certainly a possibility.” Residents of the area are rightfully concerned about being exposed to these dangerous toxins potentially leaking from Superfund sites.

Superfund sites in Houston are vulnerable to flooding

Extreme temperatures, sea level rise, decreased permafrost, increased heavy precipitation events, increased flood risks, increased frequency and intensity of wildfires, and increased intensity of hurricanes—all of these impacts are expected under climate change, and the EPA’s Office of Land and Emergency Management (OLEM; formerly the Office of Solid Waste and Emergency Management) considers them threats that make their programs vulnerable, as stated in their climate change adaptation implementation plan. The Superfund program, which ensures that sites littered with hazardous chemicals (often cancer-causing) get cleaned up, may be particularly vulnerable to these climate change impacts.

Photo: SenseiAlan/CC BY 2.0 (Flickr)

In a national-level vulnerability analysis, the EPA found that Superfund sites are particularly vulnerable to climate change related flooding and chronic inundation, impacts that would likely result in the “loss of remedy functionality and effectiveness indefinitely” with the possibility of hazardous chemicals being released from the site. We know that Superfund sites have flooded and overflowed previously, during Hurricane Katrina and Post-Tropical Cyclone Sandy. In 2011, the floodwaters of Hurricane Irene led to release of benzene (a highly carcinogenic substance) beyond the protective barriers of the American Cyanamid Superfund site located in New Jersey. It is therefore no surprise that the EPA took action to reinforce the infrastructure of the site to withstand similar flood heights in the future.

Of course, impacts related to climate change are not solely to blame for the devastating flooding seen in Houston. The Houston area is relatively flat and only about 50 feet above sea level, with about a 4-foot difference between the highest and lowest elevations downtown. This means that when rain falls, that water takes a long time to drain out of the city. Houston’s urban sprawl also is partly to blame—the replacement of wetlands with impermeable pavement means there is less land to soak up water after a rainfall event. Additionally, much of the infrastructure in Houston is only built to withstand flood heights associated with a 100-year flood, and the rains of Hurricane Harvey resulted in flood heights associated with a 1000-year flood! And then there is Houston’s location right outside of the Gulf of Mexico, which puts it in the path of slow-moving storms that can dump a ton of rainfall on the city. All of these factors make Houston a flood-prone area.

Who’s responsible if extreme events, made more likely by climate change, result in the release of hazardous chemicals from Superfund sites that harm public health?  

The threats of climate change could alter the liability of responsible parties under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the federal hazardous waste law under which the Superfund program is regulated. CERCLA provides three defenses to strict liability for releases of hazardous substances. The potentially responsible party (PRP) must prove that the release was “caused solely” by (1) an act of God, (2) an act of war, or (3) an act of a third party.

Environmental attorneys expect that the “act of God” defense will be used more often as natural disasters become more common and severe with climate change. Under CERCLA, an “act of God” is defined as, “an unanticipated grave natural disaster or other natural phenomenon of an exceptional, inevitable, and irresistible character, the effects of which could not have been prevented or avoided by the exercise of due care or foresight.”

Were the catastrophic floods of Hurricane Harvey an “act of God?”

Some types of extreme events are more likely to occur with climate change, including heavier precipitation events (see Fig 1-08) that result in flooding. Additionally, it is expected that hurricanes will become more intense as a result of climate change. As my colleague Brenda Ekwurzel points out, global hurricane models that compare the past three decades with further climate change (RCP 4.5) toward the end of the century show an increase of average hurricane intensity, precipitation rates, and the number and occurrence of days with intense category 4 and 5 storms. However, hurricanes that develop over the U.S. North Atlantic Ocean may not necessarily fall in line with this global trend. We also know that sea levels are rising, increasing coastal flood risks.

We will continue to understand more as extreme weather scientists investigate the relative contribution of climate change to the impacts of Hurricane Harvey (via attribution science), but it is important to note that we already know that extreme floods are more likely to occur under global climate change scenarios. In other words, extreme flood events are foreseeable (i.e., not an “act of God”). This is the reason why Executive Order 13690, which had bipartisan support, created more stringent federal flood risk management standards that took into consideration the link between climate change and floods to increase the resilience of federal infrastructure. President Trump rescinded this order only weeks before Hurricane Harvey hit.

What would the courts do if hazardous chemicals were found to escape a Superfund site, harming the people of Houston, in the devastating wake of Harvey?

Prior cases may give us an indication. A decision by the U.S. Court of Appeals for the Second Court in 2014, in which the “act of war” defense relieved World Trade Center owners and lessees of Superfund liability for toxic dust that infiltrated a building blocks away due to the 9-11 terrorist attacks, could be cited as a case for the proposition that hazardous chemical releases from Superfund sites during extreme events should be considered “acts of God.” This is because the court, in dicta, likened the attacks of a tornado (an extreme event) to an “act of God.” “It would be absurd to impose CERCLA liability on the owners of property that is demolished and dispersed by a tornado”, the court said. “A tornado, which scatters dust and all else, is the ‘sole cause’ of the environmental damage left in its wake.”

Professor Michael Gerrard, director of Columbia Law School’s Center for Climate Change Law said that comparisons between terrorist attacks, tornados, and climate change would be dubious, “A tornado or terrorist attack in a particular location is not foreseeable; not so with sea level rise and the associated coastal flooding.” Gerrard said that “whether or not the act of God or third-party defenses are available will depend in part on whether adequate precautions were taken against foreseeable risks.” So far, the “act of God” defense has been disfavored by courts when toxins have leaked from sites during extreme weather events—these decisions may bode well for future decisions on predictable climate change impacts to Superfund sites.

Regardless of who is or is not responsible for such harm, we hope that the EPA is working to make Superfund sites more resilient to the impacts of climate change, especially as extreme floods become more common in the future.