The key elements of Cognition’s works on this challenging site included:

• Excavation, screening, segregation and bioremediation of contamination hotspots within landfill
• Dynamic compaction of subgrade soil for construction of adoptable roads and landfill area to improve geotechnical properties of fill and reduce disposal volumes
• Construction of clay cut-off wall along downgradient boundary of landfill to intercept and channel groundwater through permeable reactive gates filled with activated carbon to absorb free-phase hydrocarbons
• Screening of excavated landfill to segregate and remove all waste and deleterious material
• Treated landfill soil stockpiled for re-use under a Materials Management Plan
• Stabilisation and formation of piling mats
• Cut and fill of landfill material to meet development topography
• Clean soil stockpiled on site placed as clean cover within gardens, landscaped areas, public open spaces and school playing fields
• Roads cut across the site and recompacted using the deep impact roller to ensure the subgrade material met the CBR target for road formation
• Geo-environmental testing and validation reporting to regulators
• Specialist activities were also undertaken including ground gas monitoring, piling risk assessment, groundwater monitoring, and air fibre monitoring for asbestos

The remediation techniques employed during the project transformed a seemingly unusable plot of land into a high-quality area for development. The work resulted in minimal on-site and off-site materials movement and maximised re-use of materials, including landfill. Our risk-based approach ensured that both the wider environment and future residents are protected, in keeping with the principles of the Definition of Waste Code of Practice. Post completion water monitoring showed an overall improvement in water quality demonstrating the success of the remediation scheme.