The quarrying industry uses much of the UK's inert wastes for restoration, with many taking hundreds of thousands of tonnes per year.
The industry has had to fight its corner before about threats to this supply of material. In the late 1990s, the industry suffered a "severe" shortage following the introduction of the landfill tax (ENDS Report 276, pp 20-23 
).
Waste was being diverted to activities exempt from waste management licensing - those where it is "used" in construction and other activities rather than simply sent for disposal. It took two years of lobbying to get an exemption from landfill tax for quarry restoration (ENDS Report 295, p 42 ).
However, the QPA and Confederation of British Industry are now echoing such concerns in relation to the PPC regime. The Agency is using the regime to bring landfill sites up to standards required by the EU's groundwater and landfill Directives.
Inert landfill operators have to apply for permits in three tranches, the deadline for the first having passed in May. The Agency has so far processed nine applications, refusing one because the company - Webfell Waste Management of Wakefield - was in administration. It expects to process 299 applications in total.
The Agency's treatment of such applications is, however, causing consternation in the quarrying industry.
"The way the Agency is interpreting the landfill Directive is requiring us to have a geological barrier - a lining basically - to protect groundwater," says Alan Shepherd, chairman of the QPA's waste and legislation group. "The cost of that means we can't compete with [exempt] activities. And that means we can't restore. And if we can't restore, we can't extract."
"I can't understand why they're doing it," he adds. "If it's inert, surely there isn't any potential pollution?"
Under the Directive, inert sites must have a geological barrier at least one metre thick with a permeability of 1.0 x 10-7 metres per second. If they do not have one, a lining is required.
Many quarries and mineral workings - being sand and gravel sites close to the water table - do not meet these requirements. However, Member States are allowed to alter the requirements if a risk assessment shows the landfill poses no risk to groundwater. The Agency's criteria for such risk assessments are not making that possible, though, the QPA claims.
According to Leslie Heasman of environmental consultancy M J Carter Associates, a firm that has worked on at least six risk assessments, the assumptions the Agency requires in risk assessments about the quality of an inert landfill's leachate means it will always come out as polluting groundwater and, hence, require a lining.
The Agency is using the limit values specified in the Directive's waste acceptance criteria, but according to Ms Heasman, "no landfill" can pass these for List 1 substances such as mercury or cadmium. "You're in the ridiculous situation where naturally excavated soils fail the test," she said.
In some cases the Agency is also requiring "rogue loads" to be factored into the risk assessment, which only serves to exacerbate the situation. The system of checks under waste licensing is supposed to stop such loads entering the system.
"The Agency seems to be taking a rigorous interpretation of the word of the regulations without giving due weight to the risk assessment or any consideration to the overall environmental impacts," says Ms Heasman.
If such sites are lined, says Mr Shepherd of the QPA, there is a "real danger" that the cost of the lining - and of the leachate and water control and monitoring systems that go with it - will make inert landfills uncompetitive compared with sites exempt from PPC. "We're finding it more and more difficult already to attract material."
It would not be possible to turn the sites into water bodies, he adds, as many require restoration as part of their planning permission. The Civil Aviation Authority's guidelines on the prevention of aircraft bird strike makes it difficult to create water bodies within 13 kilometres of airports. According to a QPA study, this affects 75% of mineral workings in the Trent Valley.
The QPA is "in the process" of quantifying how many mineral workings could be affected by a shortage of material, and has begun talks with the Agency - through the landfill regulation group's sub-group on inert landfills - on possible solutions to the problem.
At the moment, though, the QPA says the only economic solution could be for mineral workings to become non-hazardous landfills. Many non-hazardous sites are currently failing to get PPC permits due to the requirements of the groundwater Directive (ENDS Report 364, pp 15-16 ).
The Agency responded to the QPA and CBI's criticisms by restating the landfill Directive's conditions. In a statement to ENDS, it denied requiring all inert landfills to have a lining saying, "The specification of the geological barrier may be reduced on the basis of risk assessment".
The statement continues: "Our staff are alive to this issue and we look forward to working with the QPA so that we can get clarity and ensure these activities are within the right regulatory regime."
It points out that, even if the Agency changed its mind and deemed the use of inert material in mineral workings a recovery operation, the sites would still need to comply with the groundwater Directive "to ensure protection of the environment".