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Remove Mole Drains

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Remove Mole Drains

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What You Can Do

Mole drains have been installed on fields across the UK and beyond, to drain waterlogged soils and improve the yield of pasture and arable crops. Removing them will have a negative impact on productivity, but a positive impact on biodiversity, both locally and beyond the project in aquatic ecosystems.

The Pros and Cons of Mole Drains

Mole drains are terracotta or plastic pipes which run below the surface of the ground. They may be installed in ‘gripes’ or ‘grips’ – hand dug trenches which run across fields like miniature valleys. They are very effective at removing water, and could be considered essential in areas with high livestock density, to avoid poaching of soils in wet weather.

However, fields are often enriched with nitrogen fertiliser and muck, sprayed with pesticides, and/or limed to neutralise acid soils. These treatments can percolate through the ground and are more rapidly carried away, polluting local watercourses, when mole drains are present. The drains also resist the seasonal flooding of water meadows, which is an important part of many plants’ lifecycle.

Many animals (especially birds) rely on waterlogged and flooded land for winter feeding opportunities. And mole drains increase the ecosystem’s susceptibility to drought in summer.

It is essential to remove mole drains when installing a new clay-lined pond. We’ve found that an exposed tube can drain an entire pond in a matter of hours. Even blocking up the entrance with clay isn’t an effective solution – it is worth excavating the pipe back into the ground a little way, then backfilling the hole with clay.

Some landowners who are focused on ecosystem restoration have removed mole drains as part of this nature recovery process. Their work typically leads to the formation of wetlands in wetter spots and a more biodiverse grassland habitat elsewhere.

Mole drain in cow field
Old terracotta pipes typically lie one to two feet under the surface.

Removing Mole Drains

It may be relatively easy to locate mole drains, if you can find where they empty into the nearest watercourse. While we would ideally remove the entire length of the drain, this isn’t very practical, and would create a lot of soil upheaval.

Instead, these terracotta pipes and concealed plastic tubes can be broken by crushing a small section. This causes the water inside to back up, and eventually silts up the pipe. The most effective method for doing this is cutting a trench a few metres back from the margin of a field with an excavator or trencher, and crushing any pipes uncovered within the hole.

If you’re operating without machinery, it’s still possible to remove mole drains, and this is something we’ve been working towards on our pilot project. We dig a lateral trench across selected low-lying areas with a spade, where mole drains are most likely to be located. This helps reduce the digging required to locate each pipe, which is then smashed, before backfilling the hole.

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