Spot the borrow pits

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Many paths are made and surfaced using quarry aggregates and recycled aggregates that have to be brought in from elsewhere. That usually means a lot of fuel for transportation, and can sometimes involve difficult site access issues to get the material to where it is needed on site. This can be expensive, as well as having a large negative impact on the environment through factors like the carbon footprint involved in transporting the materials. Also, the aggregate has to be quarried from somewhere, which means more negative impact on local natural resources which cannot be replaced.

So building a path using material you can source on site is very appealing. It is more sustainable, it is usually cheaper, and it means the path will really be 'part of the landscape'.

The technique of winning was used to build this stretch of path, mining as dug materials from borrow pits in the woodland's side slope. Once the path was finished, the borrow pits were filled in and vegetation was encouraged to re-establish on top of them. It is now quite difficult to see where the pits were dug. It sounds ideal, but it is not possible on every site. For it to work, you need:

  • To find suitable borrow pit sites. They must be reasonably close to the path line, so transporting the material is not going to be too difficult or damage the ground, and there must be good access for a tracked excavator. Pits on steep slopes are no good.

tracked excavator working at borrow pit oatridge college

  • To check that the materials you can win are suitable. This is critical! The as dug material used to surface the Oatridge College path contained too much clay, and although the path looked good, it became very muddy and slippery in wet weather. There is a simple material test you can carry out that will show how well your materials will stand up to water, wear and tear. If the material on your site is not suitable, you will have to think about sourcing and bringing in aggregates to build the path surface. This is what happened at Oatridge College, and we had to bring in recycled aggregates to create a stronger path surface.

  • To make sure the borrow pits are properly backfilled and landscaped. There is no point going to a lot of trouble making a path that blends with the landscape if you leave evidence of borrow pits behind. This step needs to be properly specified in any contracts, and you will find a specification here.

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