Cognition was selected to carry out remediation and drainage works at Cannon Wharf in Lewisham, part of Barratt London’s new development of luxury residential apartments, Greenland Place. The area of the site which was remediated by Cognition, Parcel 2, was previously occupied by the Cannon Wharf Business Centre which was demolished to slab level prior to Cognition commencing the remediation work. Earlier site investigations indicated elevated concentrations of lead, PAHs and TPH within the made ground, posing a potential risk to human health and the environment.

Five hotspots of elevated TPH contamination were also identified within the soil associated with redundant underground storage tanks and drainage infrastructure. The main objective of the remediation work was to maximise the reuse of soil on site, thereby reducing the need for off-site disposal and hence reducing costs. Cognition prepared a remediation strategy which was subsequently approved by the London Borough of Lewisham and the Environment Agency.

The site was divided into a coordinate grid plan, enabling the grid validation to be carried out methodically. The entire site was dug to a reduced level and all structures and associated hotspots of contamination were excavated. All excavated material was screened, as specified in the material management plan, to determine whether it could be reused on site as backfill or required disposal. All grid squares were successfully validated prior to backfill and a total of 1233m³ of crushed concrete and 3462m³ of soil was reused on site, substantially minimising disposal costs for the client.

Cognition also delivered a significant saving for the client by designing and installing a stabilised pile mat, negating the need to import crushed concrete.

By maximising re-use and minimising disposal, Cognition has delivered a truly sustainable project whilst addressing the risks to both human health and the environment.