GB Card & Partners provided pre- purchase site assessments and technical support and, alongside the design team, helped establish the feasibility of the proposed 600 unit residential development, primary school and associated infrastructure on a former quarry and landfill site in Kent. Supplementing the pre-existing site data through provision of additional investigation, sampling and testing, GB Card & Partners undertook detailed analyses of the fill materials and groundwater to establish baseline criteria. This involved comprehensive Phase 1 and 2 investigations, detailed quantitative risk assessments for gas and groundwater, and ground modelling.
The subsequent remediation planning, geotechnical feasibility and design phases involved regular liaison with the design team and regulatory authorities, which helped identify a development plan, with appropriate engineering intervention to allow construction in a cost effective manner and to mitigate potential adverse effects from the low level contaminants present within the inert soil mass.
Construction is now well underway at the 20ha site, which has required major reprofiling of the ground and innovative geotechnical design solutions to create a terraced development platform. The 4 storey residential blocks are being supported on rafts formed directly onto dynamically compacted inert landfill material, avoiding the need for piling through a significant thickness of fill material and associated issues of potential obstructions. Major cut and fill operations are ongoing, proceeding under an Environment Agency and NHBC approved materials management plan and earthworks Specification. Ongoing geo-environmental support is being provided to monitor and mitigate the residual low-level risks to the identified receptors to meet the regulatory requirements.
GB Card & Partners continues to provide support with material management, regulatory ‘sign-off’, earthworks verification, temporary works and raft design, liaising closely with the site team, structural engineer, NHBC and Environment Agency throughout all construction phases. Erith Hills will be developed over six years, with the first Phase being complete in 2017, bringing this once undevelopable site back into use and providing much needed housing. The school is expected to have its first intake of pupils in 2018.