In January, Lafarge Cement revealed results of an internal audit showing that "rogue staff" had falsified data relating to alkalinity levels in more than one million tonnes of cement produced at Westbury, Wiltshire, since September 2002.
Cement users, such as ready-mix concrete producers, rely on alkalinity test certificates so that concrete can be mixed to meet specified performance criteria. Excessive alkali levels can cause alkali silica reaction - so-called concrete cancer - raising concerns over the integrity of structures made with the cement.
According to Lafarge, alkali levels in the cement made at Westbury increased greatly when it made changes to the make-up of raw materials. Ready-mix suppliers have launched a huge exercise to identify affected structures - and the incident has left Lafarge facing potentially massive compensation claims from customers.
On 2 February, local MP Andrew Murrison raised the incident in the House of Commons in relation to Lafarge's application to burn a fuel made from chemical wastes. Lafarge is already permitted to burn scrap tyres at Westbury.
Mr Murrison told MPs: "Given that data relating to the content of its product have been shown to be false, what confidence can we have in its assertion that the disposal of hazardous waste at the Westbury works is safe?" He pressed the Agency to investigate.
On 15 February, the Agency announced it had launched an investigation into management controls and environmental performance at Westbury. The Agency insists that it would have investigated the site anyway as a result of the falsification of alkalinity data and it was not simply reacting to political pressure.
The Agency has also refused Lafarge permission to commence a trial of chemical waste fuel until confidence in the site is restored.
In a statement, Agency area manager Tony Owen said: "We are extremely concerned that data on cement quality has been falsified and have launched a thorough investigation to see if there are any implications for environmental monitoring data." He continued: "At this stage there is no evidence to suggest problems with environmental data," but it was necessary to reassure the public.
The Agency is employing consultants to analyse data from continuous emissions monitors and six-monthly periodic monitoring carried out by Lafarge. The investigation will also look at how data are handled and reported to the Agency.
The Agency will also be able to compare operator self-monitoring with data from the Agency's own annual check monitoring at the site. The investigation is expected to take around one month.
The Agency's reliance on check monitoring data at Lafarge contrasts with its wider programme of cuts to the check monitoring programme. Check monitoring visits - which are funded by companies holding Agency permits - have fallen by three-quarters over the last four years because of concerns over the burden on industry (ENDS Report 360, pp 24-26 ).
In a statement, Lafarge said that it "welcomes" the Agency's investigation and is cooperating fully. The company said an internal inquiry found no evidence of falsification of environmental data. The site is certified under both international environmental management standard ISO14001 and the European EMAS scheme.
Lafarge said it had implemented new testing and reporting procedures for cement quality to prevent falsification happening again. Staff involved in the incident no longer work for the company.
Doubts over the practice of operator self-regulation were raised recently when Avonmouth chemical company Sevalco was fined £240,000 for excessive emissions of cyanide into the Severn estuary. Sevalco staff had deceived the Agency for more than four years by falsifying monitoring records to conceal the breaches (ENDS Report 359, pp 23-26 ).