PUBLISHED IN THE CASCADIA WEEKLY

September 20, 2006

Why clean up mercury?

Mercury in the environment persistently cycles through various chemical forms. The most toxic form, methylmercury, builds up in fish and presents a health risk to animals and humans that eat fish, and an even greater risk to developing babies exposed through placenta and mother’s milk. Methylmercury adversely affects brain development, resulting in decreased IQ, memory, language, and fine motor abilities in people, and in foraging and nesting behaviors in fish and birds. In Bellingham Bay, there are 10-13 tons of mercury buried in the sediment.

ARTICLE:

UNDERSTANDING CLEANUP CHOICES

As stated in this column, three weeks ago, it is the position of the North Sound Baykeeper and RE Sources that mercury cleanup in the Whatcom Waterway and ASB should be protective and permanent. To us, this means the mercury should be removed to the minimum cleanup level or MCL (see below), all of the mercury should be cleaned where it exists (even down to 11 feet), and the contaminated sediment should be placed in a certified upland disposal facility.

Next week, the Department of Ecology (Ecology) will release its draft decision-making document, the Remedial Investigation/Feasibility Study (RI/FS). The RI/FS will present several cleanup options and will identify one as their preferred remedy. Upon the RI/FS release, there will be a 60 day public comment period. Because Ecology needs to consider public opinion in their final decision, your voice can affect the ultimate cleanup.

To understand the differences between potential cleanup remedies, it is useful to understand three basic choices underlying the overall cleanup decision: the cleanup standard, cleanup depth, and cleanup and removal method.

 

Cleanup standard

There are three standards that Ecology can use for mercury cleanups in Bellingham Bay.

• The SQS or sediment quality standard is the level where no harmful effects to marine critters are expected. (0.41 parts per million (ppm)  mercury in sediment) 
• The MCL or minimum cleanup level is the level where some harmful effects may occur. (0.59 ppm)
• The BSL or bioaccumulation screening level is the sediment level Ecology believes presents an unacceptable risk to those who eat fish from the local area. (1.2 ppm) We believe the BSL should be lower than 1.2 ppm to account for sensitivity of children and developing babies.

Cleanup can be mandated at any one of the three standards. The BSL, however, can only be used if biological tests (bioassays) are run and allowed to override the results of chemical tests. If a series of three bioassays shows that test animals aren’t significantly affected by the contamination, bioassays essentially void the results of the previous chemical test. Unfortunately, using bioassays to override a chemical test is a flawed concept: Bioassays only test a few species for a few negative outcomes. Contamination that doesn’t affect the test organisms, may affect other organisms, including animals higher in the food chain, like you and I. In Bellingham Bay, bioassays overrode chemistry results in 80% of the samples where mercury levels were between the MCL and BSL! That means that mercury cleanup doesn’t have to be considered at 19 sites, even though the mercury levels are considered high enough to pose harmful effects to living organisms. 

Cleanup Depth:

Ecology typically mandates cleanup in the biological zone, or the upper 4-5 inches of sediment. Cleanup of deeper sediments, up to 3 feet, can occur if they’re believed likely to re-contaminate this upper biological zone. In Bellingham Bay, mercury contamination is as high as 2.55 ppm in the biological zone. Mercury in deeper sediments, up to 11 feet below the surface, can be as high as a whopping 12 ppm. Buried mercury can be disrupted by storms, propellers, anchors and biological activity, and some is located in erosional areas. The depth to which Ecology will mandate cleanup will be from less than half a foot to 3 or 11 feet.

 

Cleanup and disposal method:

The actual cleanup of mercury can occur in several ways. Contaminated sediment can be capped (buried with clean sediment), or removed. If the sediment is removed, it can be placed in the ASB or in a certified upland landfill. If the mercury is placed in the ASB, it will still be on the waterfront.  

I hope this brief outline of the cleanup choices is helpful as you think about what cleanup should look like. It is important – and it is time­- that we all ask ourselves, and Ecology, some critical questions, including, “How clean is clean enough?” 

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