Mortimer Road, Mitcham

Green Earth Management Company (GEMCO) provided remediation design and environmental consultancy to a regional home builder and their project team during the development of a former industrial estate, which had also formerly been the site of a town gas works.

Site Prior to Remediation

Site Prior to Remediation

The site posed a number of challenges including disused underground storage tanks, buried gas holder bases, deep foundations and hotspots of soil contaminated with TPH, PAH and heavy metals which exceeded the site specific reuse limits for a residential end use.
The risk assessment identified potential risks to human health and remediation was required. In addition to the soil contamination GEMCO removed all buried obstructions to enable piling to go ahead unhindered. The resulting materials were subsequently graded to provide suitable engineering fill for use in the backfilling operations and to provide a working platform for tracked plant.
450 cubic metres of contaminated soils were treated by ex-situ bioremediation to remove the organic contamination and to reduce the waste classification to Non-Hazardous. During treatment, soil samples from the treated materials were collected and sent to an independent lab for testing. The testing requirements were tailored to the identified contaminants of concern, namely TPH and Speciated PAH. The results of the testing confirmed the success of the treatment methodology and the soils were deemed suitable for use within the development.
GEMCO removed contaminated materials to the full depth along with contaminated perched water, which was disposed offsite via tankers.

Tar Tank

Tar Tank

The hazardous material was unsuitable for treatment on site and was taken to an offsite processing centre for treatment of hazardous waste.

 

Validation

GEMCO recognise that the most crucial part of the development is obtaining regulatory ‘sign-off’ and discharge of relevant land quality conditions with insurers such as the NHBC.

Removal of perched water

Removal of perched water

GEMCO successfully validated all private gardens and areas of public open space.

Site following remediation

Site following remediation

GEMCO saved the developer both time and money and ensured all planning and land quality conditions were satisfied in time for completion and occupation.

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