The Avenue regeneration scheme is a £95 million remediation and landscaping project and represents one of the largest brownfield redevelopment schemes currently undertaken in the UK by the Homes and Communities Agency. Delivered by VSD Avenue, a joint venture between VolkerStevin, Sita Remediation and DEC—the project required extensive geotechnical engineering solutions to ensure long-term ground stability.

A key challenge emerged along the western boundary of the site, where a 250-metre-long cut slope, approximately 6 metres high and formed at a gradient of 1V:2.7H, began to show signs of instability. The slope consisted of Made Ground overlying firm to stiff mottled clay and weathered Coal Measures deposits, typical of complex brownfield ground conditions.

During construction, wide tension cracks and superficial ground disturbances developed across the slope face. These defects indicated progressive slope instability and posed a significant risk to the safety and longevity of the development.

A geotechnical analysis conducted by Amec Foster Wheeler identified elevated groundwater levels as the primary cause of failure. Prolonged periods of heavy rainfall led to increased pore water pressure within the slope, particularly behind a low-permeability clay layer. This pressure build-up reduced soil shear strength and ultimately triggered slope movement.