“Dear Aunty, why do drill cuttings not have to be treated the same as fracking flowback fluid?” asks Fred at Counterbalance.
What a good question. And easy to answer my dears.
The Environmental Permitting Regulations specify that a liquid waste from oil and gas production that contains >1 Becquerel per litre of Radium-226 must be defined as radioactive waste, and its management must be subject to an environmental permit.
A solid waste, however, can contain up to 5 Becquerels per gram of Radium-226 before it is recognised as radioactive waste and therefore subject to the permitting regime. Solids containing Radium-226 at less than 5 Becquerels per gram are ‘out of scope’ of the Regulations.
Why is this poppets?
Well, there are several reasons.
Firstly, although the likelihood and consequences are low, and thus so is the risk, spilled liquid can run off to enter surface waters and soil and therefore get into the environment in ways and places we’d rather it didn’t. Solid rock cuttings, on the other hand, would simply form a neat little pile if spilled from a skip, and would be easier to contain and clean up.
Then there’s the fact that Radium-226, and other radionuclides, are commonly found in all sorts of rocks, clays and soils that we encounter and use all the time, cherubs. A typical house brick will contain elevated levels of radioactive Potassium-40, which is also found in the limestone chips used to tarmac our roads and pavements.
Imagine if we had to treat these common materials as radioactive material whenever we disposed of them. It just wouldn’t be sensible, especially as they present such a low risk of harm to people and the environment.
Secondly, we need to consider the mechanism of how the Radium-226 gets into the flowback waste. The fluid that’s injected into the shale rock enters the tiny fractures at high pressure, carrying in sand particles. This creates friction, and literally ‘etches’ microscopic fragments of rock from the shale that then are carried back to the surface in the flowback fluid, and it is these minuscule particles that contain the radioactive metal Radium-226.
In the drill cuttings, the much larger rock fragments are simply carried back to the surface and, because they have not been subjected to the same etching process, the microscopic pieces of rock containing Radium-226 have not been mobilised in the same way. Where rock is ground up into small solids during the drilling process, these are still not as mobile as the microscopic ones that get into the flowback fluid and are nevertheless recirculated back into the wells themselves and therefore stay underground.
You’ll see that time has nothing to do with it, nullifying this worry:
“After all, if the flowback fluid has only been down there for a few weeks to absorb the radiation and other chemicals, and that means it has to be subject to all sorts of processes to refine and clean it, how can it possibly be more ‘dangerous’ than the ground up rocks that have exactly the same radiation and chemicals, but have been there for millions of years acquiring them?”
Put simply, flowback waste containing low levels of Naturally Occurring Radioactive Material, or NORM, is subject to higher standards and safeguards simply because it’s a liquid. Solid rock cuttings are quite legitimately out of scope of current regulatory controls provided Radium-226 remains below 5 Becquerels per gram.
It’s worth noting, my loves, that the Environment Agency hasn’t made this distinction between liquid and solid wastes: it simply enforces the regulations – they’re made by others, including DEFRA and DECC, and typically transpose international and EU rules into the UK system of environmental laws. The EA can be trusted to enforce the regulations.
You might find this guidance useful https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69503/pb13632-ep-guidance-rsr-110909.pdf although it is rather heavy going dears.
Until next time xxx