Essar Oil has been fined almost £500,000 for breaching environmental rules at its Stanlow Oil Refinery in northwest England, according to a release.

The company pleaded guilty to three breaches of its environmental permit relating to two separate incidents in 2012.

In July of that year, steam and oil were released from the refinery after the roof of an oil storage tank failed under pressure. Fine droplets of oil fell across parts of Ellesmere Port, and the company incurred significant clean-up costs.

In a separate incident in August, approximately five tons of oil entered the Manchester Ship Canal following failures in the operation of Essar’s effluent management system. The waterway was closed to all shipping traffic for two days while an extensive clean-up operation was carried out.

At Chester Crown Court this week, Essar Oil was fined £497,284 ($759,000) and ordered to pay costs of £40,000 ($61,000).

Nigel Glasgow from the Environment Agency, which took the case to court, said: “These pollution incidents were significant events resulting in large numbers of complaints and clean-up costs for Essar. Permit breaches of this nature are taken seriously by regulators and the courts.

“Since these incidents the Environment Agency has worked closely with Essar, who have improved their environmental performance, and we look forward to their continued co-operation.”

A spokesperson for Essar Oil UK said that the company conducted a thorough investigation following the two incidents and implemented measures to ensure they could not happen again.

“In both cases, there were no safety or health impacts for employees or the public, and we worked closely with specialist contractors to minimize and address any issues,” the spokesperson added. “We would like to apologize again for any inconvenience caused.”