Cryalls Lane, Sittingbourne - Remediation
A DIY retail unit was to be developed on the site of a disused chalk quarry. The site’s previous uses include pesticide production which had resulted in significant ground contamination. The site had been monitored for many years and the level of ground water contamination was seen as acceptable and to be slowly diminishing. Further extensive testing and monitoring of the ground was carried out before a solution for remediation would be agreed between Environmental Engineers and the Environment Agency.
It was stipulated that the development should not increase the levels of contamination found in the ground water. Additionally contaminated soil had to be retained on site. It was agreed to seal the site and restrict the surface water discharge to a single soakaway deep below the level of contamination, thereby significantly reducing the amount of surface water percolating through the contaminated ground.
The existing quarry was filled with Type 1 fill material previously used to re-level the site, and which had been contaminated. The material was compacted in layers to form an engineered fill and was subject to extensive quality control and checking procedures. The entire site was capped with 1m of inert engineered material before impermeable hardstandings and buildings were constructed.
Below ground drainage and services ducting needed careful detailing to ensure pipework was protected against ingress of contamination.
