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Since the cyclohexane released did not ignite or explode, the internal contingency plan was not activated.

On December 16, plant personnel noted disruptions of the cyclohexane supply. As a consequence, systems were checked but no problem could be found. With the supply irregularities continuing, the manifold was inspected on the next day, and a cyclohexane leak was discovered based on the odour the leak emanated. Once the origin of the leak had been isolated, the manifold's outlet valve was closed, thereby stopping the release.

A network of 25 existing wells distributed around the chemical platform was adapted to create a hydraulic barrier. This measure confined the pollution to the industrial site and prevented the migration downstream.

Offsite samples of the water showed no contamination with cyclohexane that would have been above the consumption threshold.

Freshwater (e.g. pond, lake, stream)

The released cyclohexane entered the soil and infiltrated the underground aquifer. Most of the substance spread out at the top of the underground water table, and 1% of the released quantity dissolved in the water.

The pollution resulted in a large risk of contamination of the community's drinking water reservoirs and agricultural pumping stations located downstream in the region.

With the pollution spreading under the site, in August 2003 remedial activities were taken that limited the expansion of the pollution under the site to an area of 600 m by 300 m. The thickness of the supernatant cyclohexane layer reached a maximum of about 10 centimetres.

The overall cost of this leak and the resulting actions was estimated at 2 million Euros.

In August 2003, piezometres were drilled (special precautions to prevent the risk of explosion) to determine the extent of the pollution, to pump the supernatant cyclohexane, to draw off the gases (venting), and to perform additional analyses. Two cyclohexane fixation wells with a water table barrier and four control piezometres were drilled. A sparging barrier (300 m) was set up along the site's northern limit to reinforce the existing hydraulic barrier. These actions limited the expansion of the pollutant and kept it confined to the industrial site.

In July 2004, 590 tons of cyclohexane had been recovered from the ground by skimming of the supernatant, venting, and sparging. Since the amount of recovered substance was, however, saturating, a long-term remediation strategy was required.

A prefectural order was issued that requested that risk analysis be conducted within the scope of a remediation plan.

There is a need for real-time output measurements on all lines. This information should be reported to the control room and trigger an alarm in case of supply irregularities.

There is also a need for leak detection systems to quickly identify the source of the release.

Personnel should consider that a release might have occurred in case supply irregularities on a line is detected.

The accident highlighted several organisational issues that should be addressed. More specifically:
- Inspection programmes are needed to check the status of equipment (e.g. steam tracing, pipeway). This also includes the designation of personnel in charge of carrying out these verification actions.
- Personnel should be trained to allow them to quickly identify and react to solve problems quickly and effectively.
- Procedures should be established to give instructions on how to react in case of a release. Procedures should also be set up for lines that are not used (e.g. draining the line, closing valves, etc.)
- Effective communication is needed between the operator (or operators in case responsibilities are shared between several departments), authorities and communities around the site. This includes the sharing of complete information about the accident and its evolution.

Response to the leak confirmed the efficiency of the hydraulic barrier installed in the 1980s following a severe pollution accident.