In a oil storage, a flow of foam concentrate was detected in two inspection panels: one inside the other outside the fire protection room. The product appeared to have flowed for 72 hours, and the loss of foam concentrate was estimated at 24 m³.

The foam production system consisted of three compressed water and foam units, including GE1 and GE2, equipped with a water cooling system. The water supply was the same for the production of foam and cooling of the units; the two systems were separated by valves.

The operator carried out an investigation through simulating the incident by filling the foam concentrate tank with water, which led to identifying several defects. Following modification works on the DCI pipes, tests were performed on 5th January, using the three compressed water units and one of the two foam concentrate units (GE2); GE1 was not used and its inflow-outflow systems were closed during the operation. During the tests, the motorised valve placed on the GE2 cooling system was inoperable: it was opened manually and left in this position after testing in order to ensure proper cooling of the motor in the fire configuration. In addition, the check valve downstream of pump GE1 opened due to failure or an absence of valve loading. The foam concentrate flowed by gravity into the GE2 cooling circuit after passing through the pump housing of GE1 and while the foam concentrate proportioner was stopped. The purge valve of the GE2 cooling system was open, and the product arrived at the purge inspection panel and external inspection panel before flowing into the RHONE River through a former unclogged pipe (despite certified handover of the room’s waterproofing). The isolation valve of the external inspection panel was opened in anticipation of heavy rainfall.

All site activities were stopped (works, hot spots, product movements). The fire department, the Classified Facilities Inspectorate, the Prefecture and the CHST were all informed. An order of foam concentrate was placed, and the delivery took place 3 days later. The foam concentrate contained PFOS (perfluorooctanesulfonate: a toxic and persistent agent), and the cost of soil and groundwater clean-up was estimated at between €500,000 and €2,500,000. The stored amounts of this type of foam concentrate were replaced. The operator planned on installing motorised ball valves (“inball”) to study the introduction of remote gauging equipment on the foam concentrate capacity with alarms, in order to replace the valve and verify the loading of the other DCI installation valves. The operator also anticipated sealing the former pipe and updating the system drawings. The discharge of foam concentrate had already created a major PFOS pollution event in the groundwater 1 year prior on the neighbouring site run by the same operator.