Since late April, the operator of an aviation fuel storage and distribution company had noticed significant irregularities between his physical stocks and the associated accounting. The employees initially checked the volumetric meters on the trucks, then the gauges of the storage tanks and finally the temperature sensors on the supplier’s premises; the sensors were found to be faulty and were repaired.

Following a search, a leak was located in late June on 60 m length of steel pipe, line No.5, covered by a layer of asphalt and buried at a depth of 1.30 m. Further investigations allowed several leaks to be found at the distribution station. An estimated 270 m³ of JET A1 fuel had been lost. Line No. 5 was shut down.

A specialised company performed several core sampling operations at the site, particularly near this pipe. Samples taken at a depth of approximately 2.50 m did not indicate the presence of hydrocarbons. A second company was contacted to take samples at much greater depths. Part of the equipment excavated during the drilling operations exhibited a strong hydrocarbon smell, indicating the presence of fuel starting at depth of around 3 m. Underground water samples taken using a piezometer confirmed that the fuel had reached the water table at roughly 40 m below the ground. A skimming unit was installed near the most polluted zone to pump the supernatant phase of the hydrocarbons from the water table. Ground ventilation equipment was installed to facilitate degradation of the substance, the biodegradability of which has been confirmed.