Diesel spill running towards a surface water drain
At 06:45 you are refuelling your dumper from a 200-litre mobile bowser on a concrete pad. The trigger jams open and about 15 litres of diesel escapes before you get the nozzle closed. The pad falls gently towards a surface water drain about 8 m away and the fuel is already spreading in a thin film across the concrete. There is no spill kit on the bowser and the nearest one is in the site cabin 150 m away. It rained overnight, so the drain is running. A colleague tells you to hose it into the drain because it will disperse, and the site opens to the public at 08:00. The bowser is not bunded, the hose connection is dripping, and you are working alone with the site office locked.
1. Set out your immediate actions in order of priority.
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Stop the source first: close the nozzle, switch off the bowser pump and stand the nozzle in a container.
Do not hose it. That turns a small spill into a pollution incident and pushes it straight to the drain.
Protect the drain next – it is the receptor and the priority. Cover the drain inlet or build a bund of earth or sand across the slope to divert the fuel away; use a drain seal if one is available. Then contain what is already on the pad with absorbent, sand or earth, working from the outside in.
Send for the spill kit and notify the site manager. Keep people away and remove ignition sources. Recover the contaminated absorbent into a labelled, lidded container for disposal as hazardous waste – never into a skip or the drain. Record the spill, quantity, cause and actions in the environmental incident log and report it through the site procedure.
2. Why is hosing the spill into the drain unacceptable, and what are the consequences?
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Diesel is toxic to aquatic life and persistent, and it is lighter than water, so it spreads as a film and depletes oxygen; a litre can contaminate a very large volume of water. Surface water drains usually discharge untreated to a watercourse, not to a foul sewer, so the fuel goes directly into a stream or river.
Diluting it does not remove it – hosing simply moves the problem and increases the volume to be dealt with. Legally the polluter can be prosecuted, fined and made to pay clean-up costs, and the company's permits or discharge consents can be affected. There is also a fire risk in the drain.
The correct principle is: contain at source, protect receptors, then clean up and dispose of properly. The drain is the receptor, which is why it is protected before the spill on the pad is mopped up.
3. What should change so this does not happen again?
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Refuelling should take place at a designated, bunded point away from drains, with a drip tray under the bowser and the machine, and a spill kit at the point of use – not 150 m away.
The bowser should be bunded to at least 110% of its capacity, with a lockable nozzle and a hose in good condition; the jammed trigger and dripping coupling should be reported and repaired, not used. Refuelling should be attended throughout, with the engine off, no smoking and no mobile phone use. Staff should be trained in the spill procedure and know where the kit and drain seals are kept. The pad should drain to a blind sump or interceptor rather than to surface water. Finally, the spill should be investigated to find why the trigger jammed, and the drain identified and labelled.