Topdrill were instructed by J Murphy & Sons Ltd to carry out GI at site known as The Wilderness Cutting located in Rushton. The purpose of this investigation was to assess the stability of the embankment by carrying out a number of boreholes and trial pits. Some areas of the embankment had already shown signs of slope failure, and with this being in close proximity to a running railway line the investigation was a high priority. We were scheduled to carry out 6 windowless sampling boreholes to a maximum of 8m, and 4 trial pits to 1.2m. The combination of boreholes and trial pits at different heights on the embankment was to confirm the entire sequence of strata and to confirm the depth of the limestone bedrock.
There were various challenges with this site. Firstly the only access was very limited, through a gate and down a narrow pathway along the top of the embankment. This put constraints on the size of the rig we could use. Secondly the location of the boreholes were on the crest and midway down the embankment. This created challenges with both the logistics of placing a rig on an unstable slope, as well as with the safety of the site operatives involved.
For this site we used our specialised lightweight limited access modular rig (LLAMR). Due to the portability of each component of this rig, it can be carried down the embankment by our trained site operatives who were anchored to the top of the bank with a harness. The rig was then assembled over the correct location with minimal damage to the embankment itself.
All boreholes and trail pits were successfully completed on schedule with no damage to the embankment and without the need to stop train movement.