Building Our Clay Pond
Our community members were really excited to get a wildlife pond set up in the garden, we just needed to work out the best way to do so. Our site is sadly contaminated with mercury, so we needed to make sure none of the contaminants in the soil would be able to leach into the pond water and hurt any wildlife that decided to move in. One option would be to line the pond with plastic but, in the long term, this plastic will degrade and further contribute to pollution. Tiny organisms in the water could ingest the plastic particles and become ill, as well as any bigger organisms like frogs or newts that eat these.
Upon digging in the site we discovered that there were lots of clay deposits, and clay can form a waterproof barrier which can stop pollutants from moving around! Clay has an ionic structure (I added a picture of the structure so you can see) that can trap metal contaminants within it's layers, holding them there. We hoped if we used the clay as a lining for the pond, it would hold any mercury metal that was trying to enter the pond, whilst holding the water in. Two birds, one stone!
I'll have to say, making the clay lining is a messy job! Once the hole was dug, we mixed our excavated clay with water to soften it up and make it easier to mold onto the pond surface. Using a tool (in this case a flat-edged rock), we flattened the clay out so it made a nice even coating. We then left the clay to bake in the sun, hopefully hardening it enough to make it waterproof. Once it was solid, we used rainwater that had collected in our water butts to fill the pond. The water came with a few midge larvae and beetles which will kickstart the pond ecosystem once the sediment has settled down. This was quite evident when after a week a toad appeared! We were so excited to see the first big life in our little pond - I wonder what else will appear once we've gotten it planted up?
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