BiogenGreenfinch has been fined by Bedford Magistrates Court for polluting a mile of a stream in Bedfordshire.
The Environment Agency said the pollution was avoidable and it should have been motified sooner so that the incident could have been better managed.
In 19 November 2010, a pump was left on overnight at the company’s Clapham Biogas plant and as a result, a large quantity of digestate from an anaerobic digester overflowed.
When a member of staff arrived at work at 4am, they saw the liquid running down the road.
An hour later, another employee saw more liquid in a field close to the firm’s pig unit.
The tank had no alarm systen and had to be turned off manually.
Miriam Tordoff prosecuting said that by the time the Environment Agency was informed of the incident, it was late afternoon and an investigating officer struggled to assess the effect and take samples in the dark after arriving on site half an hour after being notified.
The building that housed the AD tank had a tide mark on the door about 6 inches from the ground, which indicated the level the digestate had reached.
The Environment Agency officer also noted that there were puddles on both sides of the road and in a trench that had been dug by staff to try to prevent the liquid reaching the pig unit.
Bedford Magistrates Court was told that daylight the next day revealed that the pollution had not been held back by dams constructed by stadd, and the company was advised on how to improve their effectiveness.
Pollution continued to overflow beyond the dams and into the stream for at least two more days.
Managers of the site told Environment Agency officers that during an upgrade in June 2010, the original alarm system was deactivated and due to an oversight had not been replaced.
The company was fined £5,000 and had to pay costs of £4,677.