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A Path Revetment Project Maintaining Your Moat The OCVWay


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So you've just got yourself a castle and you're having some problems with the moat. Where do you turn? Well, if you're an MP then maybe you could get some specialist contractors in and try to claim the whole thing on expenses! But, if you're a parish council with a limited budget and the responsibility to maintain rights of way whilst managing land for wildlife then you should come to OCV – this is what we do.


Figure 1: Aerial view of the castle site

Actually, it isn't exactly a moat around the site of Deddington Castle (figure 1), it's more of a steep defensive ditch on three sides of the site, and it's probably never been filled with water. There isn't much of the castle left either. The wooden castle built after the Norman Conquest was eventually replaced with a stone structure in the 12th century, but it had fallen into disrepair by the 14th century, so it's hardly surprising that the stonework has long since been sold off or pinched by the locals. Apart from a Norman archway in a local house, the rest of the walls are buried under the grass and that part of the site is managed by English Heritage. We were working in the bottom of the ditch for Deddington Parish Council who maintain the public footpath through the woodland.


Figure 2: The problem with the existing path

As people wouldn't want to walk along the steep sloping banks it's natural that the path ends up running along the lowest point of the ditch, but this is also the place where puddles form in wet weather (figure 2). So the path soon becomes muddy and it gets wider and wider as people try to avoid the worst patches. This in turn makes a bigger area muddy, until it starts to look like a battlefield.

One solution would be to build a raised boardwalk to keep everyone's feet off the wet ground, but boardwalks are expensive, labour intensive to build and require regular maintenance. It would be hard to justify all of this when it's not even muddy all year round. Another possibility would be to spread bark chippings on the surface, but this would only be a temporary solution and would need renewing regularly.


Figure 3: The position of our revetment boards and the new path

Instead, our solution was to create a new level path slightly up the side of one of the banks, and use boards to create revetments that hold the soil up (figure 3). This means that the bulk of the water drains into the lowest section, leaving the path mud-free. Since people don't need to walk round the puddles, the path doesn't get too wide and more space is left as potential habitat for the wildlife in the wood. Then the wet ground may even become an advantage rather than a problem, increasing the diversity of habitat on the site.

Ideally the path shouldn't be completely level. It should be easy to walk on but draining slightly into the ditch, so puddles are minimised. This also avoids eroding the banks too much and causing slippage, though this would be unlikely in this case given the density of the vegetation.


Figure 4: After the revetments have gone in

It's best to build up the path with soil from the floor of the valley or the opposite side. There were plenty of places where footfall and mud had left bare ground so we didn't even need to cut through surface vegetation. Most people started the task digging, building up a big line of soil along the route of the new path (figure 4). A few others started putting in the boards and then gradually people switched over from digging out soil to spreading and levelling as the boards went in.


Figure 5: Close up of the revetment boards

The revetments were made of boards each 25mm x 150mm x 3m. These are quite strong if enough pegs are used and they are bashed in far enough and nailed to the boards (figure 5). The nails are not strictly required but help to prevent anything being kicked out before the ground settles. About 3 or 4 pegs per board seemed to be about right. The pegs were 40mm x 40mm x 250mm long. The ground was even softer than we anticipated, so longer pegs would probably have been better, but these ones did the job. It's surprisingly hard to get the pegs in straight and in the right place, but this is the sort of thing that experienced OCVers are good at fiddling with, and there was much debating about what constituted 'good-enough'. We took great care that nothing was left sticking out that could be a trip hazard. All the wood was pressure treated so it will last in the ground without rotting, potentially for decades.


Figure 6: Completed path showing scrub blocking old path

It's important to make sure that the new path is actually used; in fact, it's often said there is no point making a new route unless you close the old one. I've seen beautiful paths that have clearly never been used because there was an existing path and people just automatically followed the footprints that were there already, so you need to erase any evidence of the old route. You can close a path with knowledge of psychology and a few big piles of scrub (figure 6). The big piles of scrub needn't be impenetrable. They just need to be big enough that you wouldn't climb over them just to walk your dog. Particular attention is needed at the start and end to try to gently funnel people on to the new path. It's important to walk up and down it and see where you would go if you'd not seen it before, and where you'd go if you walked your dog on the old path every day. Fortunately for us both the old and new paths were nice smooth curves. It would be hard to replace a straight path with one that winds rounds because people would always find a way to take the short cut. The piles of scrub blocking the old path may look a bit ugly, but will be overgrown in no time and make great habitat as they decay.


Figure 7: The end result!

We did a similar project at this site in 2008, and it was good to see that it had worked very well. The path now clearly followed the new route and was much narrower and drier. The boards were still straight and holding up the path. Scrub covered the floor of the valley and the remains of the dead scrub barricades were almost hidden. The roots from grass and scrub growing alongside the revetments should help to keep the ground solid, perhaps even after the boards have begun to decay.

Further Reading

Chris Skepper

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