Technique of the Week: Plastic Piling
We’re launching a new ‘series’ of blogs and content here at CCC – every so often we’ll talk about a peatland restoration technique in a short blog, shedding light on what is a very unknown subject.
First off, why do we need to restore peatland?
Peatland is a hugely important habitat for so many reasons – take a look at our blog here which talks about a few.
Luckily, we’ve realised just how necessary they are, and so funding is being made available for restoration works.
Peatlands are a very complex habitat, with complicated hydrology and lots of factors affecting them. Because of that, there are loads of different techniques to restore them.
With that being said, let’s look at one of the methods to block drains and ditches – plastic piling.
Because peatlands are typically waterlogged, man-made drains and ditches are put into the system so that they can be used for things like farming or forestry. To restore a peatland, these must be blocked correctly so that water doesn’t drain off in this way - see the image to the right for an example of what a typical drain looks like.
Looking at the example image below, you can hopefully see that there are large sheets of plastic sunk into the peat both at the bottom and to the sides of the ditch, creating a seal which water cannot drain through. Plastic piling should have a spillway at the top – a shorter piece which allows excess water to flow over, therefore preventing water spilling around the sides and simply creating new pathways to the drain (and weakening the drain blocking plastic as well).
As you can imagine, these large sheets can be tricky to get on site, and the sheets themselves are expensive. In addition, they’re plastic, and there’s some concern about plastic leaching downstream. Over time, exposure to the weather leaves them brittle and more prone to breaking, although hopefully at that point the drain has filled in with sphagnum and stabilised.
Peat dams – a natural way of blocking drains – are usually preferred. Unfortunately, if a ditch is really wide, steep, or the cost of getting an excavator on site for peat dam creation is too high, plastic piling may be the only suitable option.