Case Studies
Oil Pollution of Water Courses
Cadogans has been involved in two cases where oil from a tank is alleged to have polluted water courses. In one case fish at a fish farm died.
There are two main issues where such pollution is concerned: the way in which the oil escaped; and how it got to the water course.
Fish farm – reason for the spillage
In the case of the fish farm, an oil tank in a school was being filled from a tanker. The tank consisted of two halves, connected by a narrow pipe. It is probable that the oil was being delivered too quickly for the levels to equalise in the two tanks. As a result a large quantity of oil flowed out of the overflow, onto a paved area and into an adjacent drain. Unfortunately there was no interceptor or catchpit in the drain so any oil that spilled passed straight to the sewer. There were issues to do with the visibility of the gauges on the tank. From the tanker it was not possible to see the vent on the paved area above the tank.
In this case we were not asked to consider the pathway from the oil tank to the water course and the fish farm. However, in another case our evidence hinged on this.
Demolition – route of the spillage
As part of the demolition of an industrial site an old oil tank had to be removed. The demolition contractor started to dismantle the bund surrounding the tank before realising that there was a residue of heavy fuel oil in the tank. In order to remove the oil, the contractor poured kerosene into the tank to dissolve the oil.
Unknown to the contractor, there was a cut in the outlet pipe so that the oil/kerosene mixture flowed out of the tank, into the remains of the bund and thence to a nearby stream.
It was alleged that, if the bund had not been demolished, the oil would have been contained. Cadogans instructed a video drains survey which showed that the drain adjacent to the demolished bund was blocked and showed no sign of oil contamination. On the other hand, excavation at the intact side of the bund showed evidence of oil leakage at low level and the drains showed signs of oil. It was concluded that the oil would have leaked out of the damaged bund even if it had not been partially demolished.
