05 Dec 2006
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Drilling at Wareham Channel
BAE Systems Environmental
The 117ha Holton Heath National Nature Reserve is located within the boundaries of the former Royal Naval Cordite Factory RNCF) in Dorset. The RNCF manufactured naval gun propellant and explosives such as cordite, picrite and tetryl and associated ammunition between 1915 and 1957.
BAE Systems Environmental were commissioned by the Environment Agency and Purbeck District Council to assist in determining whether Holton Heath was a ‘Special Site’ under Part IIA of the Environmental Protection Act 1990.
The initial phase of the investigation, a ’B20(b) Inspection’, involved a thorough visual assessment of the site and included sampling of surface water bodies and the shallow sub soil in accordance with statutory guidance.
The results of this exercise enabled the initial Conceptual Site Model to be refined resulting in the identification of a number of potential pollutant linkages considered likely to exist at the site. The key potential contaminants identified included asbestos, polyaromatic hydrocarbons and an area of historic tipping containing a range of substances, these being noted as areas for further investigation.
Based on the findings of the B20(b) Inspection, an extensive programme of asbestos monitoring was carried out to establish whether there were any airborne fibres emanating from the site.
An intrusive B.20(c) inspection was subsequently commissioned involving trial pits and boreholes with gas and groundwater monitoring installations. In-situ testing was conducted during sitework including falling head and constant discharge permeability testing to determine groundwater flow and potential migration pathways.
A programme of chemical laboratory testing was completed for a range of contaminants including metals, hydrocarbons, inorganics and explosives. Geotechnical testing was also conducted to determine the physical ground conditions to allow modelling of the groundwater flow and potential contaminant migration.
The works were designed in consultation with English Nature in order to minimise the impact on the nature reserve’s many sensitive habitats. The presence of potential radiological, explosives and asbestos contamination, and a busy railway crossing, required particular attention to be given to health and safety planning prior to the investigation.
The results of the B.20(c) Inspection were used by BAE Systems Environmental to conduct detailed quantitative human health and controlled water risk assessments, and evaluated the significance of the pollutant linkages using Environment Agency policy and guidance documents. The assessment concluded with our opinion of whether the site met the definition of ‘contaminated land’ detailed in the Environmental Protection Act. All reports were provided in hard copy and in indexed electronic PDF format.
BAE Systems Environmental have also been contracted by Dorset County Council to conduct further human health risk assessment and a health and safety assessment to determine the potential risks associated with a proposed public access end use for the site.
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