We were instructed to undertake a phased geotechnical and geoenvironmental investigation to inform the feasibility of a masterplan for a proposed residential development which led into supplementary assessment for detailed design and development.
Our involvement began with a Desk Study, which identified that the site had formerly operated as a print works and warehouse from the early 1970s, with buildings associated with this use still in place at the time of the initial assessment and investigation. The use as a print works raised initial concerns with regard to the potential for contamination to be present, as these older, less regulated sites, commonly identify high levels of potential contaminants.
An initial Conceptual Ground Model was derived, supported by an Exploratory Investigation which identified a ground model comprising Made Ground over the Gully Oolite Formation bedrock, at shallow depth, which is known to be a sensitive Principal Aquifer.
We implemented a number of phases of work which were aimed at the following aspects of design, and both human health and aquifer protection:
- Intrusive Ground Investigation;
- Infiltration Testing as part of detailed Sustainable Drainage design;
- Human Health Risk Assessment;
- Supplementary post-demolition investigation;
- Level 2 assessment of risks posed to Controlled Waters.
We confirmed geotechnical risks and risks posed to Controlled Waters were low, however, due to the presence of elevated levels of metal contaminants in the near surface soils and Made Ground, there was a risk posed to the end users.
In order to address this, ESP designed and validated a remediation strategy, which included the use of geotextile separator and importation of clean soils to form a cover system in gardens and landscaping. Following site assessment acceptance by the Local Authority Environmental Health Officer, the site was completed and handed over to the local Housing Association client.
Working with the Design Team and Client, we identifed and addressed the risks posed by the potentially high risk historical site, and combined with suggested remedial measures, allowing construction of a new modern residential development to provide additional housing in the local area and enable reuse of another brownfield site.