Jackfield Stabilisation

The scheme was as much environmental as geotechnical. The unstable hillside had to be secured without triggering a catastrophic landslip — on a constrained World Heritage site, alongside a live road and the River Severn, with archaeological areas, Japanese knotweed and protected species (bats, fish, reptiles, badgers and nesting birds) all to be managed. Groundwater, a major contributor to the landslides, had to be controlled throughout.

McPhillips installed more than 2,000 600mm-diameter piles reinforced with steel tubes up to 13m long, over 500 250mm concrete piles and over 500 rotary displacement piles, alongside swales, ditches, ponds and a stone revetment along the river frontage to drain and protect the bank. A geotechnical engineer designed the temporary works and methodology, with ground movement, groundwater and river levels monitored daily, while a Consultant Ecological Clerk of Works oversaw flora translocation, hibernacula and weekly environmental inspections. An innovative vibrated pile-installation technique secured R&D tax relief.

With the hillside stabilised, McPhillips reconstructed the riverside road on a new alignment with architectural lighting and fencing, re-profiled the hillside and created footpaths, steps, seating and new planting for public use. The scheme was named Overall Winner and Geotechnical Award Winner at the ICE West Midlands 2017 Project Awards — recognition of an outstanding piece of civil engineering, delivered with extensive community engagement throughout.