Spill from 3rd Party
Strong odours of oil were noticed in all the downstairs rooms of two houses of a terrace. Neither had noted any spill of oil from their own oil fuelled heating systems.
Site surveys were conducted in both properties. Significant volatile organic carbons of 10 to 20 parts per million were found in the air of all rooms of the properties, significantly in excess of the usually advised limit for domestic habitation. A trench was dug along the rear of both dwellings to investigate the possible routes for ingress of oil. The trenches collected water and oil, particularly where drainage pipes from the rear of the properties entered the trench. The drainage pipes ran under the floor of both dwellings.
The occurrence of odours of oil had coincided with foundations being laid for a factory extension at the rear of both properties. With support of Environmental Agencies further investigation was undertaken here. It was found that a Fuel Transfer Line had been pierced during works, and though partially repaired, was still leaking oil. Old storm drains had been found under the site. Using tracing dye, it was shown that water went to these drains and to the drains found at the two affected properties.
The trench dug at investigation was used as an interceptor and the collected oil and water was pumped out and sent for licensed disposal.
Risks and Remediation
To mitigate the risk of further migration of oil to the properties the soils at the 3rd party spill source and in the rear gardens were excavated and sent to licensed disposal. To investigate and mitigate the risk to site users of inhalation of oil vapours, the floors in both properties were broken out to investigate impaction of underlying building materials, soils, and fill. Around 150 tonnes of oil impacted material was removed to licensed disposal to remove the source of the oil vapours.
Reinstatement work was undertaken by a specialist builder appointed by insurance.
Validation was by field monitoring and submission of soil and air samples for analysis to a UKAS accredited laboratory, and to target levels agreed by Environmental Health.Back