Former oil depot shown not to be an environmental risk
Site assessments Feasibility support
EPS had previously investigated ground conditions at a former oil depot located in an extremely sensitive location and found groundwater impacted by oils at a number of locations. Further targeted investigation was then undertaken to inform a groundwater risk assessment which successfully demonstrated that the impacts were a result of numerous small scale spills and that the surrounding water environment was not at risk, thereby avoiding a costly remediation scheme.
- The site had a significant development history and was most recently an oil depot beginning in the 1950’s with above ground fuel storage tanks present until approximately 2005. The area is directly underlain by the Chalk aquifer, which is an important regional groundwater resource for public drinking water, and the environmental sensitivity was heightened further by an adjacent surface water channel which historically extended onto site and drains to a major river.
- An initial intrusive assessment undertaken by EPS established that some areas of groundwater beneath the site had been contaminated by diesel, although there was no clear trend or limit to the impacts.
- EPS returned to undertake further targeted investigation to inform a detailed groundwater risk assessment which involved drilling additional boreholes within the depot area as well as through the historic river bed. Subsequent monitoring data was then used to conclude that the diesel impacts were a localised result of small scale spills rather than a wide spread problem caused by a major tank failure.
- Through a combination of qualitative and quantitative assessment, it was successfully demonstrated that due to the nature and distribution of the current impacts, they did not represent an unacceptable risk to either the Chalk aquifer or the river network and therefore a costly and protracted groundwater remediation scheme was neither warranted nor sustainable.
- The client was provided with clear, practical advice to ensure that the situation wasn’t changed through the planned site redevelopment, particularly in relation to the proposed foundation and drainage scheme along with an ongoing discovery strategy in case further impacts were identified during the construction phase.