Around 9:15 pm, the on-call manager of a fertiliser factory noticed the presence of liquid spread over a storage zone (designation: “POR”) and between a building and another storage area (designation “VIO”). Factory employees had been on an indefinite strike since 26th May; all workshops were shut down and no technician was allowed to be present onsite, except for the permanent on-call watchman in order to ensure minimal installation supervision. The company was scheduled to reopen on the morning of Monday 8th June. The incident, most likely caused by malicious intent, occurred during the weekend; the bottom valves on several bulk containers (1,000-litre volumes) were open, the plugs removed and the cap punctured. 11,000 litres of product, mostly hazardous to the environment (herbicides, pesticides, etc.) were spread within the “POR” zone and another 250 litres of an aliphatic hydrocarbon (solvent) spilled into the SEINE River via the stormwater network. No river pollution however was reported.
“POR” zone products flowed towards the low point of the retention basin; they were collected by the operator. A certified product disposal centre discharged the water used for the zone’s initial cleaning along with 79,000 litres of liquid waste. The cost of this elimination step was estimated at €12,000. A total of 2,000 m2 of retention would be restored to operability in order to avoid any leaching of product over time.
The tank holding solvent containing heavy aromatic naphtha spread between the building and the “VIO” zone was laid out in a pallet rack with dedicated retention. The container valve would have been deliberately moved to a point outside the retention. Liquid spilled in the direction of a gulley connected to the stormwater network, which had been clogged by a material non-resistant to hydrocarbons. The shut-off valve should have closed automatically, thus channelling “polluted” effluent to the containment pond. The safety system recording device, which activated valve closing upon the detection of pH, TOC and UV, had been inoperable since 4th June subsequent to an electrical power outage onsite (at the time of striking electricity company staff).
Tests conducted during the 10th June site inspection revealed that safety system operations (detectors and servo valves) were unreliable, in large part due to a common failure mode generated by the recording device. The operator was issued an injunction to comply with conditions set forth in the prefectural authorisation order and moreover commissioned an evaluation of the operational safety of this instrumented system by a certified body. The operator proceeded to establish a verification protocol to ensure recording device operability by site watchmen and assessed the potential of relaying an excess in the threshold for any of the discharge-related parameters analysed to an alarm in the site watchmen’s post or directly to the site watchman should he be completing his rounds.
