The case was brought by the Environment Agency after a 2 Sisters health and safety manager submitted a report on 30 April 2009 to the Agency on works done to an effluent treatment plant in Willand, Devon.
Treated waste is discharged into Spratford Stream but a quarterly return for the same period showed there had been eight separate breaches of the site’s permit, the Agency added.
A 2 Sisters spokesperson said the company recognised that procedures were not being followed and changes have now been made.
2 Sisters Food Group was fined a total of £49,500 and ordered to pay £13,117 costs after pleading guilty to 18 offences under the Environmental Permitting Regulations 2007 between 5 January and 11 August 2009.
Since the offences, the company said it had spent £120,000 upgrading its effluent plant and operational systems.
The Environment Agency said Honiton Magistrates heard the illegal discharges had a serious impact on the Spratford Stream where at times ammonia levels were claimed to have rise to 119mg/l which almost 24 times the legal limit (5mg/l).
A survey carried out by Environment Agency biologists showed the pollution had “severely impacted” on the stream and that populations of some invertebrates had been completely wiped out.
Robert Tratt, Environment Agency senior officer, said: “These offences occurred over a period of several months and were avoidable. The company should have identified the problem sooner and put measures in place to ensure effluent from its plant was being treated to the required standard.”