HomeProjectsCrag End Landslip

Crag End Landslip

Northumberland

The 2012 Crag End landslip near Rothbury caused part of an existing 90m length of sheet pile retaining wall to fail, leading to significant cracking along the B6344 carriageway and distortion of the wall capping beam. Other sections of the road collapsed and slipped down a slope over a 300m stretch.

Socio-economic impacts and major inconvenience to residents meant the solution needed to be robust, with minimal maintenance requirements, within budget and swift, so that the road could be reopened as soon as possible.

To gain an understanding of the local geology and hydrology during early client engagement (ECI), VBA undertook downhole CCTV and geophysical testing as well as substantial field work to produce 3D models which were the basis of our design.

VBA overcame geotechnical challenges, unstable ground conditions, artesian water, difficult access, and SSSI constraints. A contiguous anchored bored-pile retaining wall was designed and constructed to support the road with deep dewatering wells on the road and lower slope to reduce groundwater pressure, which had been the root cause of the road’s historical instability.

This project consists of the following works:

  • Installation of 410nr 450 mm piles at 600 mm centres.
  • high-strength recycled API reinforcement.
  • 144nr 3-strand anchors at 1.8 m centres and 23nr 40m deep dewatering wells feeding into enhanced wetland areas.

VBA identified opportunities for environmental enhancements to the SSSI (wood pasture) and built sustainability into all decision-making. A culture focused on safety enabled our team to work 88,000 man hours without a RIDDOR, despite the high risk profile of the site.

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