REC Limited was commissioned by Costain Limited, main contractor to Felixstowe Dock and Railway Company, to provide direction to site investigations conducted at the Felixstowe Docks. The investigations were to determine the environmental risk presented by the historical contamination caused by the operation of the dock fuel tank farm which, operational since the 1930’s, held over 20,000 cubic metres of fuel.
The tank farm, predominantly consisting of above ground tanks, had been built on reclaimed land, approximately 60m from the estuary for the River’s Stour and Orwell. The site also represented a potential risk to controlled inland drainage systems which were pumped to the estuary. The UK Environment Agency (EA) was very concerned regarding the risk of impact to these regulated waters.
Previous investigations identified a high level of impact both laterally and vertically within the tank farm; contaminants included petrol, diesel, kerosene, chlorinated solvents, fuel oils and lubricant oils. Based on extensive drilling within the tank farm, the site owner was being advised to spend £2.25 million on remediation to remove any risk to future site users and the estuary itself. The remedial options ignored the geotechnical issues that would be generated.
REC conducted an extensive review of the investigations and identified the short comings in both drilling and other field techniques, and interpretation of results and recommended a further round of drilling. This was to confirm REC’s already expressed opinion that there was no risk from the impact and that the impact had been exaggerated as a result of the earlier works.
Initially, REC surrounded the tank farm with wells, beyond the source perimeter, to determine actual migration issues. REC also conducted in-tank farm testing of product recovery theories to show that the oils present were not mobile or significant thickness.
Once the EA were presented with the initial results and the proposal for extensive monitoring over a two year period, they were given the confidence to permit REC to continue monitoring the site without the client living under the threat of an enforcement notice. The REC approach was then to collect the data necessary to prove the hydrocarbons were stable, at steady state and degrading before they could impact any sensitive receptors.
REC prides itself on its understanding of construction and development as well as the pure science of investigation. This allowed a cost effective and practical approach to be integrated with the site development. This included numerous utility lines being routed through the impacted area but at no risk of generating preferential pathways. REC’s practical approach also allowed the cost effective selection of utility materials rather than strict adherence to conservative guidelines.
In all, a project that was threatened with extensive delays and costly works outside of the remediation cost of £2.25million was signed off by the EA as ‘No Risk’ and requiring no further works by the EA, with all works completed for under £0.2million