Proposals to carry out the re-alignment of a highway through a rock promontory required detailed ground investigation of the ground conditions on a nearby mountainside above Loch Lomond.
Boreholes were required at a number of locations across the hillside, with rock core retrieval down to 30 metres.
Due to the steep, wooded nature of the site, several borehole locations were inaccessible to conventional drill rigs. This demanded an innovative approach to plant with live traffic running below the work site at all times.
CAN mobilised one of its rotary masts mounted on an A-frame specifically designed to work on steep rock faces. The rig was easily split into major components and lifted onto a flat area of hillside by helicopter for reassembly.
Temporary anchors were designed, installed and tested prior to being used as suspension points for the rig, with localised scaffold platforms.
A temporary catch fence was installed beneath the works area using rockfall netting and wire rope, to provide total security for road users below.
The A-frame drill rig was manoeuvred between borehole locations, controlled by the two-man drill team using twin on-board winches. Personnel used rope access techniques to safeguard themselves at all times whilst on steep slopes.
Core retrieval successfully achieved to at least 30 metres at all of the required locations.
Duration: 5 weeks – in two phases
Client: Structural Soils
Location: Loch Lomond, Argyll and Bute