The EA confirmed last Thursday that a fifth change to the company’s environmental permit for the Preston New Road shale gas site had been approved, allowing the use of a technique known as nitrogen lifting.
This technique, a standard process used in the oil and gas industry to assist in initiating well production, uses the inert gas nitrogen to encourage liquids, such as fracking and formation fluids, to the surface of a well when it cannot flow by itself or can be used to increase production.
In May, Cuadrilla breached three of its environmental permitting conditions, according to the EA’s audit of the Preston New Road shale gas exploration site.
The audit showed that as nitrogen was injected into the well, with intermittent flaring, the concentration of methane in the gas entering the flares dropped to less than 40%, the minimum level needed for them to light. But Cuadrilla’s permit had prevented the company from venting unburnt gases except for in an emergency – until now.
Following a Best Available Techniques (BAT) assessment, the EA agreed with Cuadrilla’s air quality modelling that the level of vented methane would have “minimal environmental impact” and did not “represent a risk of harm to people”.
The EA said that benzene was the main likely air pollutant in venting at Preston New Road but that this would be “well below the short-term environmental standard” and would not cause significant pollution if carried out for no more than 30 days, the maximum allowed under the permit change, the EA said.
It said Cuadrilla would be required to analyse the gas going into the flare for the presence of benzene and to report on these emissions every 10 days, instead of the current requirement of every 28 days.
To read the permit decision in full click here.