At 8 00 a.m., the empty sight gauge with float ball broke while the contents of a compartment of a 36 m³ fuel-oil tank were being pumped out at a company that sells fuel oil. The driver shut off the valve on the customer’s side, but this only raised the pressure in the circuit and caused the leak to flow out faster. He then tried to shut off the bottom valves on the tank so as to cut off the leak’s supply, but the contact switch was seized. In all, 1400 l of fuel oil flowed into a catchpit and 1600 l flowed into the wastewater system. The firefighters spread absorbent and deployed booms on the storm water storage system. The contents of the catchpit were pumped out by a specialist company. The diesel contained in the wastewater was treated by the town’s wastewater treatment plant.

The driver, who had started at the company three weeks earlier, wasn’t experienced in handling the equipment. He had no cloths with him to staunch the leak and did not think to pull out the air hoses on the desiccator in order to close the bottom valves.

To prevent this incident recurring, the operator plans to:

•  Make checking of sight gauges with float balls part of the procedure to check tanks each time they come in for servicing after every 30,000 km.
•  Increase drivers’ awareness that they need to visually check sight gauges with float balls and about what to do if a sight gauge breaks.
•  Provide cloths to be used during emptying operations.
•  Regularly check the closure contact switches on the bottom valves.