Bo Peep Shaft Investigation

BAM Ritchies has carried out the investigation of Bo Peep Shaft 3 for BAM Nuttall Rail South on behalf of Network Rail South with consultant Halcrow. All the work was carried out during a 48-hour weekend possession.

The main purpose of the work was to locate a construction shaft approximately 35m below ground level and to determine what the material in the shaft was like. This shaft was created about 200 years ago and used for building the railway tunnel. The investigative work ws spilt into two parts, namely surface drilling and drilling in the tunnel.

The drilling at the surface was carried out using a Deltabase 520 adapted by Bam Ritchies Plant so that holes could be drilled at 35 and 50 degrees using GeoborS wireline rotary drilling techniques. The first hole went well to 14.30m, intersecting the edge of the shaft and recovered some soft shaft backfill material. The second hole also went well to 17m and went through the middle of the shaft again recovering the shaft backfill material.

The drilling in the tunnel involved coring one hole at 35 degrees into the roof of the tunnel to 10.5m using a purpose-built drill 14m mast attached to a road/rail machine. This hole intercepted the shaft at nine metres.

Article courtesy of www.railwaystrategies.co.uk April / May 2011