The Arley Consulting Company Limited was commissioned by Morris & Spottiswood (M&S) to undertake an assessment of ground conditions at a relatively new development in Colne, Burnley. M&S were making shallow excavation to the external areas of a detached garage (as requested by the NHBC) when they encountered gross oil/hydrocarbon contamination. TACCL were notified and attended site to provide recommendations for the investigation/assessment of the contamination.
Samples of the impacted soils and the shallow perched water were recovered for chemical testing. The test results proved the contamination was kerosene. The source of the kerosene was a heating oil tank located in the garage. A fuel line that supplied the residential property with kerosene from the tank had ruptured approximately 500 mm bgl beneath the garage door.
On closer inspection the fuel line was located with the same conduit as the mains electric and a potable water supply pipeline. It was considered likely that the rupture of the fuel pipeline had occurred during installation.
Due to the remoteness of the location, the potable water supply was from a borehole located approximately 25 m from the leaking pipeline. TACCL advised that the local authority should be advised as soon as possible.
Further assessment of the incident identified other problems associated with the development these being (i) the water supply pipelines were not buried deep enough (out of the frost risk area), (ii) the heating oil tank was not fitted in accordance with UK regulations, (iii) other service pipelines were at risk from the oil contamination, (iv), the oil could have impacted on quality of drinking water, (v) electric, water and oil services should not be located within the same conduit.