Coal Ash Spill Impact Can Be Measured With Science

SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem. 

The February coal-ash spill, has polluted the Dan River for a stretch of more than 70 miles so far.

The ash, a byproduct of coal burning power plants, contains all of the elements that won't burn, including arsenic, mercury, lead, and other heavy metals, many of which are toxic. This is a human concern because a major reservoir in Virginia is down river, though municipal water treatment plants should be able to remove the elements from the drinking water supply. The effects on wildlife remains to be seen. How did this happen? The coal burning Dan River Steam Station in Eden, North Carolina, was in operation for 63 years, from 1949 to 2012. Waste ash from the coal plant was stored in a huge ash pond nearby. In the early days there were no storage regulations, so in general, old ponds like this remain poorly contained-- by todays standards. Being exposed, they contain a slurry of ash and water.

In Eden there are storm water drain pipes running under the ash pond into the river. They are not a part of the ash pond, but they collapsed and allowed the slurry to flow into the River.

How much was released?

In excess of 80,000 tons.

That's Ken Bridle, Stewardship Director at Piedmont Land Conservancy.

That would fill 30 Olympic size pools.. It's just a tremendously large volume of material. So it's going to tend to smother whatever's in the bottom of the river. the good news is the cold weather means that BenthicMacroinvertebrates...

The critters living on the river bottom. More on those later...

...are pretty dormant and the fish aren't breeding. The bad news is we probably won't know until the weather warms up how much ecological and biological damage there's going to be.  

Data from this particular stretch of the Dan river is lacking, but we know there are endangered and uncommon species both up and downstream of the spill. It's likely some are present within the affected area.

So what will be the effect on the ecosystem?

Among other things this is going to be seen ecologically as a big sediment plume.

The term plume describes the movement of the sediment-- in this case the coal ash.

Sediment in a river acts like smoke in the air. Both have distinct and coherent origins, but they disperse as they flow through the system. Depending on what the river does, the material in the plume responds accordingly. Sediment in a fast-flowing flood-type situation moves differently than sediment in a slow-moving situation.

If there are any mussels, clams they're probably going to get smothered. There's a lot of fish that actually will nest in the bottom. They won't be able to breed and lay eggs.

The best way to assess the impact on the river, once the spring rolls around, is to take samples of Benthic Macroinvertebrates.

Benthic means living at the bottom and Macroinvertebrates are bugs. So these are the bugs that live on the bottom of the river, and we know a lot about that ecology.

There is a diversity of species with varying tolerance to different types of pollution. The combination of the absence or presence of certain species sets acts like a code that can help determine the damage. So, for example

If you go and do a sample and basically you're looking at the entire group that is sediment-tolerant then you would say everything else that's sensitive is gone then you know you have a sediment problem.

This isn't the worst coal ash spill in US history.

There were a couple big ones in Tennessee that broke and wiped out the little communities down below. This happened couple years ago.

How can we prevent more from happening?

The more problems we start to have more people want to regulate them and clean them up and the companies will eventually have to step up. Removing the ash from the floodplains would be a good thing if you could find some ecologically acceptable place to put it and some way to get it to where you want to put it.There probably are ways of cementing over the top. Compared to like Hanford nuclear reactor sites in Washington this is a small problem. In those cases they are having to dig up big areas of contaminated soil put in a liner put all contaminated soil back in and covered it up. You could do the same sort of thing here but it's going to cost somebody to do that.

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