Geologic Boreholes & Systems, a U.K.-based company located in Honiton, Devon, was contracted to drill three boreholes to provide heat collection to a ground source heat pump, however, the project was far from simple. The geology presented the first problem, with running sands across the site, requiring around 164 feet of each borehole to be drilled using temporary casing.

After extensive research about the site, using office data regarding the geology, the firm decided to use a shell and auger rig to advance the casing through the sands. This decision was taken to limit the impact on the garden area, and because a standard rotary rig would struggle to advance the casing through this complex geology. Once the casing was installed through the sands, the geology would change to hard-packed mudstone that would require a rotary rig to progress the borehole.

The second problem: Access to the site prevented the firm from simply towing the rig into the site and positioning it. Moreover, the proximity of electricity lines around the site prevented the crew from using a standard crane to lift the rigs into position.

As a result, Geologic Boreholes & Systems called in the services of the largest demountable lorry-mounted crane in the country, which was parked in the client’s driveway. From there, the crane then lifted the rigs into position. The 1.76-ton rig was lifted more than 50 feet horizontally and 36 feet vertically, and tested the limit of the crane’s performance.

Test lifts were undertaken to ensure the lift was possible. It was such an unusual sight – there were significant onlookers, and, at one point, a passing police car even stopped to have a look at what was going on.

Once in position, the shell and auger rig installed the casing through the sands. The rotary rig then drilled to depth, and the loops were installed. The loops were installed and grouted as the casing was removed from the boreholes. The rigs then were lifted back out of the site.

The heat pump now is connected and commissioned, and the client is enjoying the use of the heating system.

To learn more about Geologic Boreholes & Systems and its capabilities, visit www.geologicboreholes.co.uk.