A food composting firm previously fined over pollution has been told to stop taking in waste after the Environment Agency found E.coli and salmonella on its site. The Environment Agency says there is a serious risk of pollution at Wormtech, Caerwent.

A substance known as leachate (which is produced by the composting process) was found leaking from the wall of a building used for food waste deliveries, and coming off the back of a compost mound. Samples taken from leachate on the site found high levels of ammoniacal nitrogen, which is toxic to fish at low levels. E.coli and salmonella were also detected.

The agency has served a notice suspending Wormtech’s environment permit effective immediately, meaning it cannot bring any waste until it proves it has sealed its buildings.

Wormtech handles 10,000 tonnes of food and green waste a year for the Torfaen and Blaenau Gwent councils, as well as food waste for Monmouthshire.

All three councils say they are finding or already have alternative arrangements in place.

The move comes after the agency demanded improvements to one of Wormtech’s buildings over pollution concerns earlier this month.

It was fined £41,000 in May 2011 after polluting a water supply and forcing a Ministry of Defence training base into quarantine for three months.