In order to fill a lorry with phenol, an operator undertook the necessary steps but forgot to position the loading arm. The three detectors on the filling station were defective and did not indicate a flaw in the coupling manoeuvre. The filling pump was stopped once the incident was noticed and the lorry washed. As a consequence, the retention basin at the filling station contained 10 m³ of water and 1.3 tonnes of phenol. The incident is not reported. The following day, an employee emptied the retention basin by sending its content into canal n°4 (that finally discharges into the Rhône river), without conducting any preliminary analysis (not required by the procedure).
The TOC metering device at the discharge outlet of the filling station retention and the phenol meter positioned at the outfall of the unit indicated contradictory values that were not correctly interpreted by facility operators; thus resulting in the release of 1 tonne of pollutant into the RHONE River.
The discharge of phenol in the Rhone river resulted from a combination of technical and organisational failures: defective sensors and / or in the wrong place, in-house lack of feedback on incident, inadequate training of personnel, incomplete procedures and instructions in particular regarding degraded mode of operations (misinterpretations of operators on erroneous data)… The operator restored the defective sensors and moves the TOC metering device controlling the effluent in channel 4. A training program is committed for the technicians, a new procedure is developed for discharge operations.
No direct environmental impact is observed ; however, 3 months later, 5 t of dead fishes will be found on the river banks (ARIA 4476). Two other series of dead fishes will happend in 1993 (ARIA 4562 et 4826)