During an exceptionally wet winter in 2020/2021 cracks started to appear along the edge of a main road in West Devon. Frederick Sherrell Limited undertook an initial engineering geological inspection for the Local Authority and concluded that the most likely cause was the poor condition of an old retaining wall supporting the side of an embankment. A follow-up ground investigation using boreholes was carried out. Crack monitoring of the road surface and inclinometer readings in the boreholes indicated a deteriorating situation with accelerated ground movement so the road was immediately closed. The outer edge of the road failed soon afterwards.
Conceptual design options for remedial works were presented in the Geotechnical Design Report, which were then reviewed and costed by the Local Authority. The preferred solution was to construct a new geogrid reinforced embankment. Further geotechnical design for the embankment option was carried out by Frederick Sherrell Limited prior to the start of works on site. During construction, an engineering geologist attended site to verify that the ground conditions encountered were as expected.