CASE STUDY: SITE INVESTIGATION, SHIBDEN COLLAPSED WALL SECTION
Project: 5 No. rotary boreholes to determine the cause of wall collapse
Location: Kell Lane, Shibden, Halifax
Client: Calderdale Council
Engineer: Mouchel
Over the years, various sections of this wall had collapsed and been repaired, however, more recently, and just on the other side of the road to this latest damage, a large section of the wall had fallen and an unrecorded mine shaft had opened up nearby. The council had commissioned a specialist contractor to grout up the shaft and another to rebuild the wall but with this latest collapse being so close to the previous one there were suspicions that a secondary adit may be present.
As the wall was right next to the carriageway and to avoid a full road closure, a temporary platform was built on which to stand the rig. Traffic management was also used to minimise the impact to the public and to prevent accidents being caused as a result of this work.
Van Elle were commissioned to drill 5 rotary boreholes to determine whether the collapse was, in fact, due to mine workings or natural subsidence.
Across the 5 locations, the boreholes were terminated at depths of between 12.5m and 14.0m bgl. The ground conditions experienced were similar and comprised of made ground down to 0.6m, yellow clay to 2.2m, weathered mudstone to 4.1m, shale to 8.7m, coal to 8.85m and mudstone beneath that to an undetermined depth.
The rig used was the Comacchio MC305 drilling 5 No. 100mm diameter boreholes. A factual report was presented to the client with our findings.
