The client, United Utilities Water Limited (UU), was fined £600,000.
Both UU and the KMI Plus contracting joint venture pleaded guilty at Bolton Crown Court to polluting a brook in a prosecution brought by the Environment Agency.
The companies were also ordered to pay a total of £45,262 in costs (United Utilities £19,090 and KMI Plus £26,172).
KMI Plus is a joint venture between Kier, J Murphy & Sons, Interserve Construction and Mouchel, formed in 2002 to work in the water and wastewater sector.
The court heard how KMI Plus was contracted by UU to carry out improvement works at Wayoh water treatment works at Turton Bottoms. In December 2013, as part of the works, KMI Plus emptied and removed a tank which had been used to store sodium hypochlorite in 10% solution. Sodium hypochlorite is used in the water purification process and is also the principle ingredient of household bleach. It is very corrosive and is highly toxic to aquatic organisms.
The court heard that by 4th December 2013 the majority of the contents of the tank had been removed but up to 300 litres of the chemical was left in the bottom and needed to be emptied.
The Environment Agency’s prosecutor told the court that instead of pumping or siphoning the remaining liquid out, a decision was taken to put a hosepipe into the tank and dilute the sodium hypochlorite with water, letting it overflow into a bunded area and leave the hosepipe running unattended overnight for 15 hours. This was carried out without any risk assessment or method statement and the companies were not in agreement on what they understood had been agreed prior to the removal taking place. Neither company had surveyed the drainage adequately and did not realise there were faults in the drainage system which meant the diluted toxic chemical entered the surface water drainage system and discharged to Bradshaw Brook, a trout spawning ground.
On 6th December 2013 the Environment Agency was alerted by a member of the public who had found dead fish floating in the water. A 1.7km stretch of the brook leading towards Jumbles Reservoir was so badly polluted that virtually all aquatic organisms, including fish, shrimp and earthworms were killed. Up to 900 dead fish were recovered, including Brown Trout, Loaches and Bullheads, but the number killed is likely to have been much greater. At the end of June 2014 the brook had recovered sufficiently for restocking to take place and UU paid for the brook to be restocked with native fish from the downstream section.
The Honorary Recorder of Bolton, Judge Timothy Clayson said the incident had arisen through senior management failings to ensure proper system and procedures were in place.
Gordon Whitaker, environment manager of the Environment Agency, said: “This was a serious and avoidable pollution incident caused by the negligence of both parties. It took several months for Bradshaw Brook to return to a healthy state and even then it was necessary to assist this process by restocking fish in the affected stretch. This case should bring home the message to all company directors and shareholders that environmental offences are taken seriously both by the regulators and the courts.”