Lyneham Banks landslip may have been triggered by dumping of material

The key route linking Chippenham and Lyneham has been closed for over a year after suffering major damage in a large landslip last February, causing havoc for residents and businesses.

During a presentation setting out the solutions for repairing the busy road, Wiltshire Council revealed that a sensitive historical slip surface was likely reactivated by factors such as exceptional rainfall, changes in the groundwater regime or changes in loading on the slope.

Chris Cox, associate geotechnical engineer for the council’s contractors Atkins, said: “It’s clear that some of these aspects will have triggered the landslip.

“Changes in topography or loading on the hillslope can significantly impact the stability of the slope.

“The landslip is located in areas of historic slip surfaces. Potential changes in groundwater, as well as changes to the loading on the slope and the addition of fill, is likely to have contributed to the triggering of this landslide.”

Investigations carried out by the council and Atkins found materials, which appear to be demolition materials, were placed on the hillside above the affected stretch of road by the developers of a construction project, prior to the landslip.

This project was a scheme to demolish an existing dwelling, garage and workshop at The Banks and replace it with a detached two-storey dwelling, equipped with a garage.

Construction appears to be ongoing at the site.

One neighbour claimed that “thousands of tons” of rubble and material were dumped on the hillside by developers before the landslip, making the ground movement “inevitable.”

They added when rain hit the slope earth was seen running down the hill by locals.

Wiltshire Council emphasised that while planning permission was granted for the project, no authorisation was given for earthworks in the wider setting of the area.

The erection of the new dwelling has also been deemed “unauthorised” by the council, as works are not in accordance with the original application.

A proposed solution for repairing the road is estimated to cost around £5.9 million and is unlikely to be completed until 2025.

In the meantime, local businesses say they are “desperate” as a result of the long-term closure, which has drastically reduced their passing trade.

The landowners of the development in question could not be reached for comment.

Wiltshire Council added they do not hold any information regarding the operation which led to the deposition of the material.