On 30 October 2013, there were several indications of product losses from a tank. These were:

– Tank levels falling at a higher rate than usual in relation to the season and temperature.
– Contrary to expectations, there was no positive change in the tank contents when the temperatures fell.
– On that date, a nearby groundwater well was sounded to measure the water and product phases. The product phase was found to be conspicuously large.

The measurements carried out every two months by an externally commissioned expert to monitor previous damage had not revealed any unusual phase sizes at an earlier stage. No conspicuous smells or obvious changes to the tank field were detected. The variation in quantities missing from the tank was comparable with other tanks.

When the information regarding the increased phase size was made available, it was considered possible that the bottom of the tank had been damaged. The emptying of the tank was started immediately. The tank was then cleaned from 11 November 2013. On 13 November 2013, the bottom of the tank could be examined. The damage was found.
Immediate emptying of the tank.

Examination of the tank bottom, limiting the damage, distinguishing it from the previous damage.
Soil/groundwater contamination
Hole in single-walled tank bottom
Similar damage is not possible when there are double bottoms.
A double bottom has been installed in the tank concerned.

Examination of the tank bottom, investigation into the cause of the damage.