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Rough Science 6 Colorado: Safety Video Diaries: Hermione Cockburn

Updated Wednesday, 9th November 2005

Exclusive video extra in which Hermione Cockburn talks about the challenge for the Safety programme, from the sixth BBC/OU TV series Rough Science, based in Colorado

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So Ellen and I have been given the challenge of cleaning up some acidic mine drainage. Now I’m really excited about this challenge for two reasons; firstly I’m working with Ellen which is always good, and secondly this is a real environmental problem that Colorado faces. I mean there are so many old mines in this area and a lot of them have this very acidic, horrible, metal-laden water streaming out of them due to the history. Now there are two ways that Ellen and I are going to go about cleaning up the mine water. I’m going to use rocks to deal with the acidity, and Ellen is going to use a bacterial biological approach to cope with the metals that are in solution.

So what have we done? Well day one we went up to see the mine and it was a beautiful area, not terribly great weather today but this real sort of - imagine a mine in the hillside and this is what it was it was like, a little tunnel, dark tunnel going into the hillside, but coming out this bright orange water. The orange staining on the riverbed is called ‘yellow boy’ and it’s an iron compound because there’s a lot of iron in the rocks. And the water is very acidic, but we’ve sort of been told this but the first thing we wanted to do was test the water. So Ellen and I had a look round, collected some samples and went back to the mill. Testing it with pH paper the acidity was really low, down to 2 or 3 I think, and that was really my challenge.

Now there are chemical ways that you can neutralise acidity, but I knew that there was limestone around in this area, and limestone is an alkaline rock, it’s made up of the remains of sea creatures, it’s essentially calcium carbonate. And if it’s crushed up this can effectively neutralise acidic water. So in the afternoon I just headed out into the hills to search for limestone, and the thing is you want to have the maximum surface area that you can for the water to touch, so to maximise the contact between your acidic mine water and the limestone so I just crushed it up, left it in a small beaker overnight, coming back on day two testing the pH of that water that had been left in the limestone and, hey presto, it had come up, the pH was now at 7 and that’s neutral.

So I knew that that was going to work on a small scale, so I was pretty confident that I could fulfil my side of the bargain. But to scale it up was actually quite hard work. It was collecting a whole load of limestone. Ellen and I wanted to fill buckets for our water treatment plant so I collected a lot of limestone, came back and basically spent day two crushing it up, again to enhance the surface area that the water would be in contact with. So Ellen fulfilled her side of the bargain which was collecting a whole load of manure, and we created the water treatment plant.

So then in the morning of day three Ellen and I got up very early to go up to see how the water treatment plant was getting on. Now interestingly, this kind of passive treatment is used for real in environmental clean up in this area, but of course they’re not trying to do it in three days. So we knew that in principle this was a good approach, but for us only just having hours to let the treatment plant settle and to let the water flow through there was really no guarantee that it was going to work, so we wanted to get up there as early as possible. Unfortunately, under the sheer weight of the water and the limestone, one of our limestone troughs had broken, the plastic had just given way so we had to remedy that. And again, that sort of set us back a bit but the water was flowing through for a good few hours, going through the bacteria rich manure, metals precipitating out we’d hope, and then through the limestone, neutralising and then out the end. We put a watering can on the end of the water treatment plant which looked quite cute and also helped aerate the water, it wasn’t just for show.

And then, so we left it for as long as we could, it’s day three, we had to then just take a sample and get back to the mill and do the final test to see whether the water fleas lived, and we’ve succeeded, miraculously. The water fleas survived, the water had had time to neutralise which I was very, very relieved about and so it was a good job. Working with Ellen again was great fun, and I’m very pleased to say that we tackled a real environmental problem.

 

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