Fracking firm Cuadrilla has published the results of its monitoring air quality for a year at its Preston New Road drilling site.
The shale gas exploration company said hundreds of thousands of separate air quality readings had been taken continuously to test for methane and nitrogen dioxide levels in the area of the two wells drilled near Little Plumpton.
Cuadrilla said there were hundreds of thousands of readings in total from each stage of the process including the drilling of the two wells and the hydraulic fracturing operations subsequently carried out between mid-October and mid-December 2018.
It said it had posted the data on its website as part of its commitment to transparency and in line with its Environmental Management and Monitoring Plan.
It added that monitoring had also been carried out from February 2016 to January 2018 to establish a ‘baseline’ of gas levels occurring in the area.
During the baseline period before site construction the British Geological Survey observed ambient methane levels of up to 70ppm.
As part of the site’s environmental permit conditions, methane levels above 7.1ppm have to be notified to the Environment Agency.
Cuadrilla said that there had been four separate instances of elevated methane levels recorded from the site since May 2018 when a continuous methane detector was installed.
It said the Environment Agency had been informed each time but that 99.7 per cent of the time the methane levels in and around the site had been below the reporting threshold of 7.1ppm.
Three short term spikes of methane were recorded between 11 and 23 January, 2019. The highest spike was 30.5ppm which is less than half of the highest level recorded during the
baseline period. This was a controlled release of methane through the flare during the well testing phase.
The fourth instance of elevated methane emissions was in October when a reading of 12.1ppm was recorded for about 10 minutes. This related to methane gas in flow back water stored in tanks.
Nick Mace, environmental manager at Cuadrilla, said: “We are very proud of the extensive monitoring programme and the resulting data set being published today. It has worked
exceptionally well and the data set is probably the most comprehensive ever gathered at a shale gas exploration site. It shows how seriously we take our environmental responsibilities at Cuadrilla.
“The absolute level of methane emissions over the 12 month reporting period is reassuringly tiny. While there were four instances of somewhat higher methane levels detected at Preston New Road, let me put these into context to reassure people.
"The instances were short in duration, very low in absolute volume and naturally occurring background methane at this level was also detected before the site existed, so it is not uncommon to see short term spikes in data.
“In addition, there are no health consequences whatsoever from very short term emissions of methane at these low concentrations.”
Cuadrilla added that the on-site air quality monitoring is mirrored by the British Geological Survey from a separate base about 450m from site designed to provide academic analysis and public reassurance.