Cognition on the home straight at Wandsworth Homebase

29 January 2021

Cognition Land and Water has been carrying out the remediation and earthworks of the former Homebasesite in Wandsworth. These works are on behalf of Legal & General Investment Management (LGIM).

This - in addition to the adjacent B&Q site, where Cognition works were completed last year - is the second part of a project that represents the Client’s largest Build-to-Rent scheme to date.

Cognition was contracted to demolish the ‘Homebase’ structure to ground level and remediate the site area. We mobilised in July 2020 and are now applying the finishing touches to withdraw from what has been a particularly successful job.

After removing the building, Cognition remediated the Site through the removal of former obstructions and re-engineering and treatment of subsoils via solidification using a cement binder. The remediated soil was stabilised, which improved the geotechnical strength of the soil as well as reducing permeability to prevent leaching of residual contaminants such as metals and PAHs.

During the works, additional geotechnical investigations were carried out to facilitate the foundation design for the scheme. Obtaining this information was not possible prior to the demolition due to the large footprint of the former building.

In addition to the site works, and through discussions with the Environment Agency, Cognition took the opportunity to help improve the local environment by voluntarily installing an offsite borehole adjacent to the River Thames to investigate an historic pollution problem unrelated to the former Homebase site. For many years, hydrocarbons have been seen leaching beneath the river wall and into the River Thames. Through significant dilution by the River Thames, this did not constitute an environmental risk but presented a constant and unsightly iridescent ‘slick’ on the river bank in the area. It is likely that these are ‘tarry’ Non-Aqueous Phase Liquids (NAPLs) emanated from the historic gasworks, which was operational in the vicinity between 1834-1949. Cognition has since deployed our unique Fabric Extraction System (FabEx) in the borehole to draw out and dispose of the hydrocarbons trapped in the groundwater and soil in the immediate area.

Remediation and enabling works are almost complete but Cognition will shortly be proceeding with additional work at the site, not part of the original scope. This includes hoarding adjustments, preparation for a sewer diversion and temporary substation installation. 

Throughout the job, Cognition has worked hard to minimise any impact on the local community and achieved an ‘Excellent’ rating from the Considerate Constructors Scheme (CCS). Very high standards of health and safety were maintained throughout the works, underpinned by our recent companywide campaign promoting ‘Health & Safety at our Core’ 

If you would like to discuss how we can bring this level of performance and professionalism to your project, please contact David Skinner at david.skinner@cognitionltd.com.