Inside a pharmaceuticals plant, a drain valve on a closed glycol water circuit stayed open and caused a product leak during the facility restart operation carried out at night.

An initial circuit drainage had been performed at the end of December to allow a subcontractor to install a meter. The operation consisted of opening a drain valve on the upper part in order to create an air inlet and then drain the lower part. The drain valve was closed upon completion of these steps. Since the drainage level was insufficient (liquid level still too high), a second drainage step would be undertaken outside the protocol; the drain valve remained open. The circuit was filled with the drained volume but not placed back into service.

During operational start-up of the circulation pumps, a flow occurred on the roof: 10 m³ of glycol water (40% monoethylene glycol) were discharged into the retention basin via the stormwater network. Following analysis, 250 m³ were transferred to the plant’s treatment unit. This incident, combined with a similar one the following day (ARIA 36103), wound up polluting the RHINE River (ARIA 35773).

The plant operator issued a reminder of plant protocol and placed plugs on all unconnected valves.