At around 2 am, a leak occurred in a dyeworks on the wastewater pipe connecting the sump to the effluent pre-treatment plant. The operator shut down the sump pumps and progressively the water-using machines (dye machines, desizing line and washing). Despite shutting down the machines, the wastewater flowed into the MORGON river from the sump, due to the load of the network (approximately 70 m³/h before the shutdown and 10 m³/h a little after). The operator waited for a pump to arrive to empty the network and repair the leak on a pipe flange joint. According to the operator, the joints used had been identified as faulty and had been changed with the exception of that one. The amount of effluents lost between 15 and 20 m³ (COD: 800 mg/l, SS: 29 mg/l, pH: 8.4) did not cause fish mortality. After replacing the joint, the installations were restarted. A similar accident occurred in the establishment the month before (ARIA no. 31733). To prevent effluents from flowing from the sump basin into the river, if pumps were shutdown, the operator installed a temporary system used for transferring the effluents to the pre-treatment plant.