Preserving Eelgrass While Remediating Legacy Contamination


What do you do when the State requires you to take action, yet prohibits that action? It’s a conundrum that takes imagination and determination.

The Setup

For over 100 years, several companies used the nearshore at the former Custom Plywood site for processing and manufacturing wood-related materials that would be used nationwide. They filled the tideland with wood, ash, bricks, metal, and sediment. They left a tug, boiler ash, scrap metal, barrels and drums, aluminum cans, scrap wood, paper, sawdust and creosote-treated pilings. As if that wasn’t enough, in 1992 a fire destroyed the mill, adding dioxin (a carcinogen) to the sediment.

The Conundrum

The Washington State Department of Ecology and Hart Crowser removed most of the contamination from the property and tidelands. Despite this, there are many acres of tidelands that are still peripherally contaminated with dioxins, much of which contains healthy eelgrass habitat. The eelgrass is not affected by the dioxin contamination; the problem is that it serves as a potential pathway for human exposure (i.e., shellfish consumption). By State mandate eelgrass must be protected. (See our earlier post about the importance of eelgrass). This means that the State requires that something be done about the contamination but not at the expense of the valuable eelgrass habitat. Our current options for dealing with dioxin contamination are to either dig up the contaminated material, or immobilize/cover it to prevent the exposure to the benthic community. Either action would potentially destroy the eelgrass. What to do?

The New Approach

The solution? Remediate the sediment in place by covering the eelgrass habitat, but not burying it. Eelgrass, unlike other species of seagrass, can only tolerate a very small level of burial. We needed to determine if the eelgrass at the former Custom Plywood site could withstand deposition of very fine layers of sand that would act as a barrier (cap) to the contamination in order to protect the benthic community and the habitat overall. Our team conducted a two-year pilot study to see whether the eelgrass could tolerate a four- or eight-inch layer of sand (applied two inches at a time), rather than a single layer application that would ordinarily be used for remediation. As part of this study, our team also investigated if adding a layer of carbon could increase the cap performance so that the cap could be as thin as possible.


Diver with eelgrass/sediment sample. Photo courtesy of Research Support Services.

The Result

The data clearly showed that eelgrass at the former Custom Plywood site can survive a four-inch cap if implemented in multiple thin layers. This means that the preferred alternative for cleaning up the residual contamination is potentially feasible. The next step is to design a large scale application using the information and data gathered from the pilot study. Eventually we hope to finally cleanup the former Custom Plywood site while leaving the existing eelgrass habitat in place and functioning.


Applying Net Environmental Benefit Analysis to Contaminated Sites

Exxon Valdez oil spill site

Exxon Valdez oil spill site.

First, do no harm….

Or at least don’t do more harm than good.

That’s the idea behind NEBA—Net Environmental Benefit Analysis—as applied to the cleanup of contaminated sites. As defined by a vintage 1990s Department of Energy paper on the subject, net environmental benefits are:

“…the gains in environmental services or other ecological properties attained by remediation or ecological restoration, minus the environmental injuries caused by those actions.”

Spills like Exxon Valdez Spurred the NEBA
The NEBA concept originated with the cleanup of large marine oil spills. One of the first formal considerations of Net Environmental Benefits was the cleanup of the Exxon Valdez oil spill in Prince William Sound, Alaska in 1989. After the spill, the U.S. National Oceanic and Atmospheric Administration (NOAA) looked at whether high-pressure, hot water washing of unconsolidated beaches might actually do more harm to the intertidal habitat—and the plants and animals that depend on it—than just simply letting the oil degrade naturally.

Since then, NEBAs have been used for a few other types of cleanups, including metals contamination in wetlands and organic contamination in sub-tidal sediment, but only infrequently and on an ad hoc basis.

No current NEBA Guidelines, However…
Formal consideration of net environmental benefits has not been more widespread in cleanup decisions, probably because federal and state cleanup frameworks, such as Washington’s Model Toxic Control Act (MTCA), do not explicitly allow consideration of the harm of the cleanup itself and don’t provide guidelines for when the process would apply and how the benefits and impacts should be evaluated.

But that might be changing. At least it is in Washington State, where the Department of Ecology thinks that the NEBA’s time has come. Ecology is working on new draft Terrestrial Ecological Evaluation (TEE) guidance that, for the first time, lays out the implementation of NEBA at cleanup sites under MTCA.

NEBA and Abandoned Underground Mines
In conjunction with Ecology, Hart Crowser has already “test driven” the NEBA concept as it applies to the cleanup of abandoned underground mines. Many of these sites pose risks to terrestrial plants and animals because of the toxic metals such as copper and zinc left behind in tailings and waste rock.

Although the risks to individual organisms living on the waste material might be high, the overall risk to plant or wildlife populations are often fairly low because the extent of the waste material is so small. Nonetheless, the remedy selection process under MTCA would typically lead to a decision to cap the contaminated material with clean soil or to dig it up and haul it away to be disposed of elsewhere.

Bringing Common Sense into Cleanup Decisions
But what if the cleanup involved building an access road? Through mature forest? Or up a steep, exposed mountain side? Or across a stream or wetland? How are those habitat or ecosystem injuries balanced against the benefits of the cleanup itself? Ecology’s upcoming NEBA guidance should go a long way to addressing these dilemmas and bringing some common sense into certain cleanup decisions.

“Especially Valuable Habitat”
The new guidance is expected to introduce the concept of “Especially Valuable Habitat” and how to use it as a threshold for judging whether or not a NEBA may be appropriate for a particular site. It’s also expected to allow some flexibility regarding how injuries and benefits are quantified and balanced.

In the meantime, check for updates on when the new guidance is expected at Ecology’s website.

Ecology’s New Freshwater Sediment Criteria

Sediment Sampling

The Washington State Department of Ecology has released Revised Sediment Management Standards that will become effective in September 2013. Differences from the existing Marine Sediment Criteria include:

  • Shorter list of compounds
  • Criteria are based on dry weight rather than organic carbon normalized
  • Total DDT (pesticide) and its degradation products are included. The compounds included in the totals are different from those used for marine sediment and soil criteria.
  • Criteria for polycyclic aromatic hydrocarbons (PAHs) are based on totals rather than individual compounds. The compounds included in the totals are different from those used for marine sediment and soil criteria.
  • Total petroleum hydrocarbon (TPH) criteria have been established. Additional sample extraction and cleanup or alternative laboratory methods may be required to remove false positive results from naturally occurring organic matter.

Laboratory detection limits must be lower than criteria and, for non-detected results, both the method detection limit and the practical quantitation limit must be reported.

Ecology may require toxicity testing in the following instances where criteria may not predict sediment impacts:

  • Sediment with unusual geochemical or biochemical characteristics influencing toxicity (release or bioavailability of contaminants) including total organic carbon in environments such as bogs and alpine wetlands.
  • Sediment with pore water or overlying water that has unusual geochemical or biochemical characteristics influencing toxicity (release or bioavailability of contaminants) including pH or hardness.
  • Sediment impacted by metals mining, metals milling, or metals smelting.
  • Sediment impacted by other toxic, radioactive, biological, or deleterious substances.

More information is on the Ecology website.

Ocean Acidification—What’s Being Done?

Ogasawara National Park

Our world’s oceans are becoming acidic nearly ten times faster than any time in the past 50 million years. This is because they absorb a percentage of the increasing amounts of carbon dioxide in the atmosphere; certain types of runoff can also contribute to the problem. Acidic oceans endanger marine life in many ways. For example, low pH seawater dissolves calcium carbonate, which is used to make shells.

The situation is especially dire for Puget Sound because of the way ocean currents work in our region. Since 2005, billions of oyster larvae in Puget Sound hatcheries have been decimated, resulting in significant loss in production and signaling profound impacts to Washington’s marine environment.

What’s being done about it? Over the last few years, a number of studies have been initiated both locally and around the world to understand the impacts and mitigate ocean acidification. A quick summary:

Washington State is a leader in taking action on ocean acidification. Former Governor Christine Gregoire created the Washington State Blue Ribbon Panel on Ocean Acidification, which convened February 2012. The panel created a report: Ocean Acidification: From Knowledge to Action (November 2012) and recommended 42 separate actions.

United States. The Federal Ocean Acidification Research and Monitoring (FOARAM) Act was enacted in 2009. Its purpose was to monitor and conduct research, establish an interagency research and monitoring program, establish a program in NOAA, assess impacts, and research adaptation strategies and techniques.

NOAA established its Ocean Acidification Program May 2011. The Interagency Working Group, which is chaired by NOAA, put out the Initial Report on Federally Funded Ocean Acidification Research and Monitoring Activities and Progress in Developing a Strategic Plan in March 2011. This report has a comprehensive outline for a Strategic Research Plan for Ocean Acidification.

World. The European Project on OCean Acidification was founded in 2008 and lasted four years. It had a consortium of 160 researchers from 32 institutes and 10 European countries. Although the project is over now, the website has a number of documents that may be downloaded.

While some important research has been done on the topic of ocean acidification, and some stopgap measures have been put in place (for example, to protect local oyster farms), we are a long way from solving this complex issue. The work has only just begun.

More information: Washington State Department of Ecology and NOAA.