Site Background & History
The site comprised of a small parcel of land forming part of the old town gasworks. Mason Evans Partnership [MEP] carried out site investigations which confirmed the presence of significant contamination associated with historical use of the site as a gas works. The prime contamination source was identified to be wastes deposited within a gas holder which was located partly on the site and partly on the adjacent site. The identified contaminants of concern were Total Petroleum Hydrocarbons, BTEX, Polycyclic Aromatic Hydrocarbons (primarily Naphthalene and Benzo(a)Pyrene), cyanide and ammonia.
The developer / client was seeking planning permission to develop the site for residential end use.
Various remediation options were considered and precluded on the basis of cost and/or inability to achieve site remediation criteria. Working closely with MEP, Envirotreat developed a remediation strategy for the site which was commercially viable and addressed the remediation requirements for the site, both in terms of groundwater / surface water and human health protection.
The site is located within close proximity to a Ramsar Site, a Special Area of Conservation, an important bird area as well as two SSSI sites. The site is bordered by a substation to the north, the tidal Kinness Burn directly adjoining the site to the east, a builder’s merchant to the south and school grounds to the west.
An integrated remediation approach was proposed to address the identified environmental and human health risks.
The strategy comprised of four key elements:
- Installation of a low permeability barrier to prevent re-contamination of the site from the section of the gas holder located under the builder’s merchant site.
- In-situ E-Clay stabilisation of contaminated soils within the gas holder.
- Installation of a E-Clay Permeable Reactive Barrier along the eastern boundary to protect the Kinness Burn from residual contamination on site.
- Installation of a suitable capping layer to address human health risks.