Nine sites have had a question mark over them, including one pig unit and pig and poultry unit. But the Environment Agency has now confirmed that these sites have been visited, talks have taken place, and none has been refused an IPPC permit.

However ‘very stringent’ improvement conditions have been imposed and the permit holders concerned will now have to produce plans to reduce emissions. Their success, or otherwise, at reducing emissions to the required level, will be reviewed in four or five years, reports the NPA.

A number of options are likely to be taken up - such as putting some pigs outdoors and introducing biogas plants. But perhaps the most important action the units can take is to commission their own ammonia emissions modelling.

This could show lower real-world emissions from a unit than the Environment Agency’s own results, which have been produced using a generic emissions model, according to Dr Selena Randall, agriculture technical manager at the Agency.

Workshops have been held for the 90 or so pig and poultry producers who the Agency says will have to reduce emissions from their IPPC units and many of these now plan to pay for their own modelling.

Dr Randall sees problems ahead for some units when the Agency has carried out its housing review because some producers will have difficulty finding the money to invest in improvements.

However, her prediction is that the Agency will want to look at drainage improvements before housing improvements, “because that is where the big wins are”.

Although making improvements to drainage may sound less expensive, there are headaches and heartaches on the way as producers start to grapple with their drainage plans.

“We know the drainage review is going to be a challenge,” said Dr Randall. “Some producers have told us they think their site is going to be a nightmare.

“Drainage is very complex on some sites. When we were preparing for this we pulled up some manhole covers at Stotfold and we found the drainage there was hugely complex. It will all depend on the site and what developments there have been on the site over the years.”

All IPPC units are required to meet Best Available Techniques (b-i-g file) by 2020.