09 Nov 2006
BAE Systems Environmental
BAE Systems Environmental was commissioned by the client to conduct an intrusive site investigation at a former landfill site currently utilised, in part, for residential purposes. The purpose of the investigation was to establish whether any part of the site met the statutory definition of ‘contaminated land’ under Part IIA of the Environmental Protection Act 1990.
The Site incorporated a residential area of approximately 8500m2. Historical maps and other information held by the local authority indicated that the site had been previously used as a refuse tip with the predominant waste being sawdust and wood chippings from a nearby sawmill. There was therefore the potential for contamination to exist at the site. The investigation of the site was designed based on the desk study information in order to confirm the initial conceptual site model.
A number of receptors needed to be considered including the residential occupiers of the site, a nearby sensitive watercourse and a designated ecological site. As the site was being utilised for residential purposes additional factors had to be taken into account in the design of the investigation. These included access restrictions, proximity to houses, septic tanks and overall consideration for the residents and their properties The site investigation therefore comprised a combination of techniques including cable percussive boreholes, window sample boreholes and hand augering. Positioning of the investigation points and the choice of methods at each location was designed to ensure minimal disturbance to residents whilst still meeting the overall objectives of the investigation.
In addition to the positioning of the boreholes a number of additional factors had also to be taken into account during the investigation including the use of tracked boards across garden areas, tarpaulins around boreholes to collect arisings for disposal to a locked skip as well as being open and transparent and willing to answer any questions from concerned residents.
Following the investigation, a large number of samples were sent for chemical analysis with some being subject to leachability testing. The selected analytical suite reflected the findings of historical investigations as well as recommendations in associated industry profiles. Groundwater samples were collected from the boreholes on two separate occasions and subject to analysis with gas monitored from the boreholes on four occasions. The results of the investigation allowed the Conceptual Site Model to be updated and identified where pollutant linkages existed. A risk assessment was then undertaken to assess the significance of the identified pollutant linkages.
This included a Generic Quantitative Risk Assessment for human health in accordance with current UK government guidance. Generic Site Assessment Criteria were derived for many substances where there are no published Soil Guideline Values.
BAE Systems (c) 2006
