Mining Remediation Authority uses innovative resin injection technique to fix a sinkhole at Marden Farm Allotments, keeping disruption to a minimum.

Drilling the collapse and inserting resin injection pipework.

Last month, the Mining Remediation Authority (MRA) responded to reports of a sinkhole at Marden Farm Allotments in North Tyneside. The team completed repairs in just 2 days.

The sinkhole was caused by a collapse in shallow, unrecorded historical mine workings beneath a paved area on one of the allotment plots.

The collapse bridged by paving.

The affected plot was full of raised beds, greenhouses and garden furniture, with only a narrow walkway leading to the collapse. A traditional dig-and-fill repair would have meant removing much of the plot infrastructure and crops and could have taken up to 2 weeks.

The exposed crown hole collapse beneath paving.

Instead, specialist contractors injected expanding resin foam into the ground through small, drilled holes, stabilising the collapse from below. Only a few paving slabs needed to be lifted, and the plot was left in good order when the work was complete.

Restricted working area with the drilling platform spanning the collapse zone.

The approach cut the job from an estimated 2 weeks down to just 2 days, at a lower cost and with far less disruption to allotment users.

Colin Campbell, the safety officer at Marden Farm Allotments, said:

From the moment they arrived, the team kept us in the loop and explained exactly what was happening. We were concerned about the disruption a repair like this might cause based on previous experience of two similar collapses when remediation action has employed excavation and backfilling techniques, but they were in and out in 2 days and you'd barely know they'd been here. We couldn't have asked for more.

The completed repairs with replaced paving slabs.

Barry Whitelaw, project manager at the MRA, said:

We knew straight away that a standard excavation would have caused real disruption to the plot holders - their allotments are important to them and we wanted to find a way to do the job with as little impact as possible.

We kept in close contact with Colin throughout and I'm really pleased we were able to find a solution that worked for everyone. To have it wrapped up in two days and leave the site just as we found it was a great result, and the team didn't let the heatwave slow them down either!

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