Ground Engineering was appointed to undertake a desk study and ground investigation at a former transformer manufacturing works, prior to the client’s proposed purchase of the property in order to identify potential risks and liability.
Historical research indicated that the site was first developed in 1916 as a transformer works, with subsequent expansion in the 1920s and 1930s. It was established, via reference to bomb damage plans and local knowledge, that the factory remained for the most part unscathed during World War II, with the exception of a ‘flying bomb’ which hit the gatehouse in 1944. In the 1960s a 25m high factory warehouse was constructed to house crane lifting gear used to enable the final assembly of large transformers which were subsequently lowered into a 12m long by 6m wide and 7m deep vacuum vessel used as the final part of the drying process prior to oil filling and sealing.
A site walkover survey was carried out as part of the desk study, in advance of the site work, to aid the design of the intrusive investigation.
The transformer works was sub-divided into a number of different areas used for different processes. There were about nine areas within the site which were identified as having been used for the storage of fuel/oil, including transformer oil which was used extensively within the manufacturing process. Two extensive mass concrete underground air raid shelters were also identified within the works, together with several deep underground chambers.
Intrusive ground investigation works comprised thirty-three machine excavated trial pits, twenty driven continuous sampling boreholes and five cable percussion boreholes which enabled access to all areas of the site. The exploratory holes were focused on known sources of fuel/oil storage locations and were located at 20m to 30m centres, to provide an overall coverage of the site.
Following the fieldwork, site specific laboratory chemical analysis was conducted on recovered soil and groundwater samples and an interpretative report provided including an assessment of the likely risk of ground contamination being present beneath the site. Assessment of the potential linkage between ground contamination sources, human and environmental receptors was also presented in the form of a conceptual model in accordance with UK Government guidance.
On the basis of the desk study and ground investigation works undertaken, the client was able to proceed with the site purchase with a fuller understanding of the liabilities associated with the underlying ground conditions.
