Plymouth Crown Court heard how a combination of equipment failure and poor management on the part of South West Water led to poorly treated sewage entering the Craddock stream, downstream from its Ashill Sewage Treatment Works, near Cullompton.
The Environment Agency found pollution in the stream in September 2013 and again in December 2013 which affected a 400 metre stretch of water and impacted on river life.
These issues resulted in a breach of the permit conditions, which require South West Water to ensure that the treatment works operate correctly and to notify the Environment Agency of any problems that might affect sewage quality. The permit conditions also require that treated sewage must be of a standard that does not cause adverse pollution or environmental harm.
The Environment Agency spotted sewage fungus in the Craddock stream on 11 September 2013 and found excessive sludge in the treatment process, and blocked filters which would usually efficiently treat the sewage. The outlet channels of the works had extensive sewage fungus, which extended downstream.
A biological survey of the stream showed that the sewage had been poorly treated for at least a month, and further investigation revealed South West Water knew of the poor stream condition. Ongoing problems were observed during a later visit on 12 December 2013, when the quality of the sewage remained poor.
The offences observed on both dates were attributed to negligence on the part of South West Water.
Judge Lawrie said the pollution of the stream was present for a sufficient length of time for sewage fungus to grow and was not a passing release of effluent.
The fact that the stream was of poor quality and that others may have contributed to that poor quality did not excuse the operator from their primary responsibility to ensure the risk of pollution from the works was kept to a realistic minimum.
He added that South West Water had failed to keep an effective watch on the maintenance and operation of this site since September 2013 and should have made more effort to ensure the site ran properly and that their maintenance programme at the site was sufficient.
The court heard that the site was to be the subject of significant investment to upgrade the works, including an additional septic tank, a new humus tank and a dry weather flow gross storm overflow.
Environment Agency spokesperson Mischka Hewins said:
We carried out regular checks on the watercourse in 2013 and saw pollution on two occasions. An ecological survey revealed that there was a detrimental impact on the invertebrate fauna of the stream as a result of the sewage treatment discharge and significant changes to the wider ecology of the stream.
South West Water was fined £300,000 for offences at Ashill Sewage Treatment Works contrary to Regulations 12 and 38 of the Environmental Permitting Regulations 2010. They were also ordered to pay the full prosecution costs of £14,421.