Northampton Magistrates Court fined Deltatrax £5,000 and ordered it to pay £5,073.28 in costs after the company pleaded guilty to discharging diesel into the Swanspool Brook, a tributary of the River Ise.

Environment Agency officer Chris Willis said after the hearing: “Oil in the water can harm wildlife, affect fish and taint drinking water at very low concentrations.

“This pollution was avoidable and continued even after it was brought to the attention of the company. Responding to the problem straight away could have avoided this becoming such a serious matter.”

The spill happened at a former pie factory in Chester Road, Wellingborough, which was being demolished.

Claire Bentley, prosecuting for the agency, said the oil polluted 700m of the brook requiring a clean-up by agency workers and contractors.

Oil was first spotted floating on the surface of the brook next to the town Castle Fields on Sunday, April 5 by a passerby.

Environment Agency officer Chris Willis traced it back to a discharge pipe behind the demolition site and tried to contain it with booms and pads.

Company representatives failed to respond to a request from the agency for an interview under caution about the issue, the court heard.

Miss Bentley said the pollution risk was foreseeable as oil was being stored in a tank, which had no secondary containment, was not bunded or secure.

Mr Gary Lewis, defending, said the company replaced the tank once it was alerted to the deficiencies by Mr Willis.

He told the court it believed the spillage had been caused by intruders and said there had been a history of vandalism and break-ins at the site, which had been derelict for some time.

Deltatrax pleaded guilty last Friday (August 20) to breaching the Water Resources Act and polluting the Swanspool Brook.

David Gibbs

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie