GEO Millerhill

Case Study: Millerhill Slope Retention

INFORMATION
Client Morgan Sindall (EGIP Alliance)
Project Edinburgh to Glasgow Improvements (EGIP) Project Millerhill Depot Embankment Works
Location Millerhill Electric Train Depot, Edinburgh
Overview Excavation, regrade and installation of soil nails including removal of injurious weeds.
 

THE CHALLENGE

Morgan Sindall appointed TRAC as a subcontractor, to plan, manage, supply and install a slope retention system, which involved excavating and re-profiling the embankment to provide toe level clearance, and the installation of 180 soil nails. The nature of the ground dictated that the embankment be secured against potential failure at all times by a netting system. Surveys had discovered a historic mineshaft in the centre of the crest space which caused substantial delays to the works begore they began. During this delay the already de-vegetated embankment became subject to the growth of Giant Hogweed, an injurious (hazardous to health) weed which had infested most of the surrounding area.

THE APPROACH

TRAC appointed a team to remove the Giant Hogweed, ensuring that no cross contamination occurred with multiple contractors working on site, and disposing of the resulting waste as is appropriate for such species. Excavated material was transported to a designated bund where the potential contaminant will be controlled by localised herbicide treatment in the subsequent years. Physical Barriers were implemented along the crest to implement safe working limits for the long-reach excavator, allowing for works to be undertaken in ALO (Any Line Open) Conditions and preventing the excavator from affecting the mine shaft. All soil nails were installed with an excavator mounted Drill Rig, eliminating the set up time associated with an A-Frame Rig, and the drill operation and bar insertion controlled by TRAC’s rope access technicians.

THE RESULTS

Despite the delays and changes caused by the mineshaft which pushed the work package into the critical path of the overall project, TRAC delivered the project as per the revised design and without impact on date of operation.