At 7 pm., 4 t of Ethylene Oxide (EO) were released into a drain bund during roadtanker loading operation on a chemical site. This was a routine operation with approximately 24 tankers loaded that same day.

An Ethylene Oxide tanker was being loaded at the bulk Ethylene Oxide storage tanks when gas detector in the bund sounded the alarm.EO was discovered overflowing from the knock out pot to the bund central drain gulley.

The release was caused by the defect of a spring operated hand valve (not closing) allowing a path from the nitrogen vent line on the loading pipework to the knock out pot. The pot was not designed to take large quantities of liquid and hence overflowed to bund. The release was contained in the bund and disposed of by on-site personnel by controlled dilution with water to the main site drains. There were no injuries and no ignition of the release which was contained within the central gully of the bund (reduced surface area for pool) and was refrigerated material. The material loss was estimated at 35 000 euros.

The operator added a manual valve in vent line and changed operating procedures. He improved the communication between the tanker loading operator and the control room/plant operators.