Located in the district of Portsmouth, in southern England, Tipner is a residential area that is under a deep regeneration scheme to bring jobs, homes and retail to the region. CampbellReith acted as design team engineers for the remediation of the site for which a planning application was required.
Site investigations had identified soils to be extensively contaminated with tarry wastes, free phase hydrocarbons, PAHs, phenols and asbestos in approximately 40,000m³ of soils; relating to a heavy industrial legacy including a chemical (tar) works, which processed gasworks waste. In addition, there is also a large plume of hydrocarbon contamination in shallow groundwaters corresponding with former tar wells and storage tank areas that presents a potentially significant risk to the nearby Portsmouth Harbour, designated as an SPA, RAMSAR and SSSI.
CampbellReith’s remit involved the reappraisal of site investigation information and the development of a revised remediation scheme for the client following local objections to an earlier remediation. Additional detailed site investigations were subsequently undertaken to further characterise the ground conditions and inform Quantitative Risk Assessment models (CONSIM and RBCA) to derive human health and controlled waters remedial targets and to aid the design / selection of the strategy and most appropriate technology.
Through public exhibitions and continuous dialogue with the regulators, CampbellReith was able to design a scheme that represented a more considered approach in view of the concerns of people living and working within the local area, but at the same time would deliver a robust and effective solution to the problem. This resulting strategy comprises a combination of in-situ free product removal and pump and treat system, onsite soil washing, ex-situ bioremediation and the installation of a Permeable Reactive Barrier around the site boundary.
In addition to the above, a complicated set of laboratory bench scale trials and onsite field studies were undertaken using a variety of viable techniques such as in-situ chemox, vacuum enhanced extraction, air sparging, bioremediation, soil washing and stabilisation/ solidification to further demonstrate their efficacy in addressing incalcitrant contaminants at the site and to refine the remedial designs. GIS was used to visualise remediation works and to infer geology and the spread of contaminant based on exploratory hole logs taken at various stages thought the scheduled works.
The main remediation works have just commenced and combine a combination of soil washing, complex sorting and bioremediation. CampbellReith prepared a comprehensive set of contract specifications to support a D&B contract, drawing upon a wide portfolio of project experience and expertise in this field. These specifications consider contamination, geotechnical and other engineering requirements whilst providing a robust yet flexible framework for the risk management of the works. CampbellReith will provide continued client and technical support.