During his rounds at around 4 pm, a refinery technician detected a crude oil leak in the area of a pipe within a cluster connected to a crude storage tank. The operator placed a 2-m platinum plating in the leaky zone and called on a subcontractor to pump the crude oil released into the ground over a 200-m² surface area. It was estimated that the leak lasted 2 hours, given that the morning inspection did not reveal anything and that the volume released amounted to 200 m³. The polluted ground was excavated manually and then sent for disposal to a certified processing centre, while 15 m3 of crude oil were pumped on the day of the accident.

External corrosion on a pipe elbow emanating from the pressure release exhaust valve on a crude oil tank was responsible for this leak, which moreover was fed by the hydrostatic pressure of crude contained in the tank. The elbow was placed half underground in a sandy soil due to erosion of a nearby embankment slope. The above-ground clusters of refinery pipes had not been maintained for a number of years in order to reduce costs, and this situation led to the partial burial of some sections due to gradual soil subsidence. Soil humidity most likely accelerated the external corrosion phenomenon in the leaking elbow. The operator had introduced a 3-year pipe cluster renovation plan (sand removal and visual verification), but the plan had yet to be implemented on the compromised pipe, which had not received any cathodic protection. The Classified Facilities inspectors requested the operator to complete, as quickly as possible, the inspection of above-ground pipe clusters subjected to ground subsidence and then replace those displaying any risk of leaking.