On December 11 2007, diesel fuel escaped from a pipe and entered the environment from the Tophill Low water treatment works, near Driffield, which supplies clean drinking water to Hull.

Yorkshire Water Services Limited (YWSL) was this week fined £8,000 and ordered to pay £1,500 in costs, plus a £15 victims surcharge.

Paul Harley, prosecuting for the Environment Agency, told the court that YWSL had discovered that fuel used to power diesel generators – which are used to pump water in the event that mains electricity is lost – had escaped into Beverley and Barmston Drain.

YWSL notified the Environment Agency and commenced a clean up operation, digging drainage sumps and putting absorbent booms in place across the watercourse.

Environment Agency officers observed a layer of red diesel on the surface of the water and saw pools of diesel on the ground near the storage tanks. Due to the quantity of fuel in the water, EA officers quickly turned off automatic pumps at the Wilfholme station to prevent diesel being pumped into the River Hull.

Two specialist waste management firms were engaged by the EA and YWSL to clean-up the spill, removing contaminated water and soil.

EA investigations found that a corroded pipe which took diesel from storage tanks to the generator building had leaked and fuel had escaped from the duct surrounding the pipe via inspection hatches. The diesel had flowed over a road and onto a grassed areas, and also into surface water drains feeding the Barmston and Beverley Drain.

During the clean-up operation, booms were used to removed diesel from the water, eight tonnes of sand had been spread on the road and 50 cubic metres of contaminated soil was removed. Nine thousand litres of diesel had been recovered.

The magistrate said the maintenance regime for the site did not include inspection of the diesel pipe, despite it being easily accessible via the duct. He said there were no procedures in place to deal with a fuel spill and no dedicated oil spill kits on site.

YWSL had paid between £35,000 and £40,000 on the cost of the clean-up and replaced the pipe.

It was noted in mitigation that there was little or no medium or long term environmental damage, and no evidence of fish kills. YWSL had pleaded guilty at the first opportunity.