Cleaning up

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Most of Vashon-Maury Island has heavy metals in the soils at or above Washington State Department of Ecology cleanup standards: 20 ppm for arsenic, 250 ppm for lead and 2 ppm for cadmium. It is pretty clear now that outside help for cleaning up the island from fallout of the Tacoma Smelter Plume will be a long time coming. But there are actually lots of things that you could do right now for little cost.

First, evaluate where the highest risks are in your surroundings. High-risk areas:

• Places where children play
• Gardens
• Where there is bare dirt

Put your greatest cleanup efforts there.

Currently, there are two basic kinds of fixes for heavy metal-contaminated soils: 1.) Removal of the contaminated soil or 2.) Burying it.

You can clean up high-risk areas by digging down 6 to 12 inches and hauling the dirt away. Contaminated soils can be disposed of at the transfer station. Disposal of soils is the surest, and also the most expensive method to clean up contamination.

If you don't want to pay tipping fees, you can fix areas by double digging them, just as you might do in making a new garden. Remove the top 12 inches of soil and place it to the side. Then remove the second twelve inches and place it in a different pile. Put the first 12 inches of soil in the hole you have now excavated and put the second 12 inches on top. You have just inverted the top 2 feet of soil, and buried those heavy metals below the root zone (which is only 8 to 12 inches deep). Double digging is the cheapest method to remediate soils.

You will probably want to add compost to your soils now, since the subsoils now on top have little organic matter in them. Adding compost to your soils and making sure that they stay near neutral acidity (pH of 7) is always a good idea in gardens or farmed areas. This combination reduces the overall risk of metal uptake by plants. Adding iron to the soil helps, too. But be careful where you get your iron from: many iron-enriched fertilizers are made from industrial wastes containing heavy metals. Adding very fine steel wool to the garden will work: make sure to mix it well into the soil.

You can also mitigate contaminated soil by covering it with clean material. You can lay down landscape cloth and cover the area with such things as:

• Beauty bark
• Clean sand. Sand, even that found here on the island, is naturally low in heavy metals.
• Wood chips, but be careful. It is known that Douglas Fir concentrates arsenic in its wood, so make sure that the wood chips don't come from Douglas Fir.
• Clean topsoil, but again, be very careful that you know where that topsoil is coming from. Some commercial topsoils are made from Ruston soils and others have industrial wastes in them that are high in heavy metals and other contaminants.

Burying heavy metal contaminants is not a permanent solution-arsenic is forever and those metals will stay more-or-less where you put them-until you or some future landowner digs them up to lay pipe or plant a tree or otherwise develop the land. This means that the burying method won't work very well where you intend to do further development. And it is a good idea to keep track of where you may have used the burying method for future reference.

Some plants naturally concentrate heavy metals, and we have some indication that there are plants growing on the island that are already doing this (for example, the Douglas Firs mentioned earlier). HMRC is working to raise money to do some on-island research to identify which island plants can do the job, and how best to grow, collect and dispose of such plants. It will take a while to figure this out, but we have been working with researchers at WSU who are confident that we CAN clean up our Islands this way.

HMRC is working to develop sources of certified clean soils, but the going is slow. We will keep you posted. We meet monthly and need more volunteers. Please call May Gerstle at 463-0974 if you can help with time or money.