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Mussels Reveal Impact of Puget Sound Stormwater

Bay Mussels

Native mussels (Mytilus trossulus) like these were used to evaluate the degree of contamination in Puget Sound nearshore habitats. Photo: Brewbooks

The mission of the Washington Department of Fish and Wildlife (WDFW) is to preserve, protect and perpetuate fish, wildlife and ecosystems while providing sustainable fish and wildlife recreational and commercial opportunities. An important initiative is evaluating the impacts to nearshore aquatic areas from stormwater discharges. Mussels sieve the water as they feed, and their tissues absorb and retain chemicals and pathogens, so the WDFW led a study using mussels as an indicator organism. They got help from so many organizations and volunteers, the list fills nearly an entire page. It includes the Snohomish County Marine Resources Council (Mike Ehlebracht, Hart Crowser geochemist, volunteers for the MRC), the Washington State Department of Ecology, other governmental agencies, native American tribes, and various non-governmental organizations. The work was funded under the new Stormwater Action Monitoring (SAM) program that is paid for by municipal stormwater permit holders.

How Was the Study Done?

As part of this study, the WDFW and volunteers placed “clean” caged mussels at over seventy locations across Puget Sound, including highly industrial areas (such as Smith Cove and Salmon Bay), urban areas like the Edmonds waterfront, and rural areas (such as the San Juan Islands). They left the caged mussels in the water for several months, then retrieved them, often in the dark, in cold and blustery weather. They tested them for stormwater-related contaminants including PAHs (produced by burning coal, fossil fuels, wood, and garbage), PCBs (used in electrical apparatuses, surface coatings, and paints; banned in the US in 1979), metals, PBDEs (used in flame retardants), DDTs (insecticides; banned in the US since 1972), and others.

And the Results…

The study showed that stormwater discharges continue to impact the nearshore aquatic environment, particularly in industrial and highly urbanized (paved) areas. PAHs and PCBs were the most ubiquitous, problematic chemicals detected in the mussels, with some of the highest concentrations found in Elliott Bay (particularly Smith Cove).

Puget Sound is a large, complex, and diverse estuary. This data will be critical in determining best management practices and providing recommendations for environmental remediation. The next round of sampling will occur this fall, with updated data available in another year or two.

Download a copy of the Stormwater Action Monitoring 2015/16 Mussel Monitoring Survey: Final Report.

Questions? Contact Mike Ehlebracht.

Placing caged mussels

Snohomish County Marine Resources Council volunteers and staff place caged mussels.

Recent Guidance on Vapor Intrusion – EPA, Washington State, Hawaii, and Oregon

Vapor intrusion occurs when there is a migration of vapor-forming chemicals from any subsurface source into an overlying building. The vapors can enter buildings through cracks in basements and foundations, or through conduits and other openings. Examples of vapor-forming chemicals that are hazardous to human health include methane (from landfills), tetrachloroethene (PCE) and trichloroethene (TCE) from dry cleaners, benzene (from petroleum products), and radon.

Soil Vapor Migration

Migration of Soil Vapors to Indoor Air
This figure depicts the migration of vapors in soil gas from contaminated soil and groundwater into buildings. Vapors in soil gas are shown to enter buildings through cracks in the foundation and openings for utility lines. Atmospheric conditions and building ventilation are shown to influence soil gas intrusion. (source: EPA)

 

Since 2000, research has shown that exposure to toxic vapors has much greater health risks than previously known. Long term exposure to even very low concentrations can result in cancer. In response, the federal and state governments have lowered the safe exposure limits, and regulators have recently updated guidance for assessing vapor intrusion.

EPA published new guidance for assessing vapor intrusion in June 2015. (OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air; OSWER Pub 9200.2-154). The document provides guidance on conducting investigations, including collecting samples; interpreting risk assessments; and mitigating vapor intrusion.

Washington State subsequently updated their guidance for vapor intrusion in February 2016 (Washington State Department of Ecology, Guidance for Evaluating Soil Vapor Intrusion in Washington State: Investigation and Remedial Action, Pub 09-09-047). This document describes Tier I Screening assessments and Tier II sampling assessments.

Hawaii published their VI guidance in 2014 (Technical Guidance Manual for the Implementation of the Hawai’i State Contingency Plan, Section 7: Soil Vapor and Indoor Air Sampling Guidance). This document provides good information on different types of sampling equipment, with photos.

The state of Oregon is using vapor intrusion guidance published in 2010 (Guidance for Assessing and Remediating Vapor Intrusion in Buildings).  The guidance describes how to perform risk-based evaluations, and the state periodically publishes updated risk-based concentrations for chemicals.

In the state of Minnesota, vapor intrusion concerns have significantly affected the real estate market. Starting in 2017, if a building is suspected of having contaminated soil below or around it, the state has asked the owners to test for vapors and fix vapor problems before the property can be sold. This can significantly add to the costs of property transfers and delay sales or even scare off buyers.

Here in the Pacific Northwest, the states are not requiring soil vapor testing, although near landfills methane vapor testing is often required.  Also, areas with known radon often require vapor mitigation systems. But your environmental consultant should be considering vapor intrusion risks during Phase I Environmental Site Assessments, and might recommend soil vapor tests during Phase II investigations. Vapor intrusion is complicated – vapors move more easily than soil or groundwater contamination. It takes careful evaluation and interpretation of the guidance and test results to help property owners and purchasers make knowledgeable decisions.

Questions? Contact Anne Conrad, (425) 775-4682

Preserving Eelgrass While Remediating Legacy Contamination

Eelgrass

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

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.

Beyond the Go-To Microbe

Microbes Feeding on Petroleum

Microbes Feeding on Petroleum

Rapid, cost-effective complete genome sequencing (CGS) has opened a universe of possibilities.  New discoveries. A better understanding of life. New ways to solve modern problems.  The new advances could some day show the innovation of CGS technology to be as important as the discovery of fire.

One problem faster CGS is solving is confirming that the “right microbes” are present for environmental cleanup. Until CGS, scientists had only classified 10% of microbes in nature, guessing how the unculturable microbes related to each other.  Supercomputers are changing this limitation.

Over the past five to ten years, bioremediation practitioners have increasingly used specialized microbial strains to help them with environmental cleanup, termed “bio-augmentation.”  For example, various strains of Dehalococcoides ethenogenes have been the go-to microbe to treat chlorinated ethenes (at dry cleaning sites, for example).  This was largely because it was one of the first species to be successfully cultured and shared among researchers.  CGS and other genetic tools have revealed numerous additional microbes are able to perform some of the specialized reactions. We can now pick a sequenced gene, check for the simple presence of that gene, and then see if that gene is present in any microbes in a soil or groundwater sample.

While the newest tools have helped us, one critical fact remains the same. Give the microbes the food, nutrients, and growing conditions they need, and they will degrade contamination into something less dangerous to people and the environment.  We continue to work with nature to fix our transgressions against it.