The UK’s landfill legacy has previously been considered a stain on our green and pleasant lands. However, piles of rubbish that were once swept under the pasture are now presenting a real opportunity. Will Simpson finds out why enhanced landfill mining is being dubbed ‘the next big thing’.
It sounds like the equivalent of ferreting through bins, albeit on a macro scale. Enhanced landfill mining is an idea that will undoubtedly stir up controversy, but it is one that could deliver a number of not-insignificant economic and environmental benefits.
First of all it’s important to differentiate enhanced landfill mining from simple landfill mining. Stuart Wagland, Senior Lecturer in Energy and Environmental Chemistry at Cranfield University, who is also the Chair of the UK Enhanced Landfill Mining Network explains: “Landfill mining is purely the excavation of material from a closed site done more for the purpose of eventually developing the land for housing or industrial developments.”
“Enhanced landfill mining, however, goes a bit further than that. So you recover more resources – metals, plastics, other commodities – as well as waste for energy and then you remediate the site for redevelopment.”
There are a number of drivers behind this. When landfills were first created they were often on the outskirts of towns. Now, at a time when demand for new housing is at an all-time high, these sites represent huge opportunities for developers. “They are right where you want them and usually have good transport links already,” says Andrew Turner, Director of the consultancy Madano and a member of the Enhanced Landfill Mining Network. Further, some landfills are regulated whereas others are not, with some lying on flood plains or coastlines where rising sea levels and increasing flood risks slowly erode their banks, releasing rubbish out to sea.
And then there is the recovery aspect. Sending material to landfill has a far longer history than the recycling sector. There are unquestionably huge volumes of material available, which in 2021 would automatically be recycled and which could now be recovered easily through mining landfill sites; lithium, cobalt, copper, aluminium, gold and silver, as well as many durable plastics. From a financial perspective, the cost of excavation could be completely covered from the sale of recovered resources, before the significant value of the repurposed land is factored in.
“In the past, the whole concept of a circular economy wasn’t as developed as it is today,” Turner explains. “In 2021, many rare earth metals – lithium for example – are highly prized. There are only a few places in the world where you can mine them. But we can now go into these landfill sites, recover materials that are maybe very expensive or in short supply and put them to good use.”
To this end, the Enhanced Landfill Mining Network was set up last year, comprising consultancies, universities and many other stakeholders, to facilitate the development of enhanced landfill mining in the UK.
It all sounds thoroughly logical. There are, however, potential roadblocks. Local media, for one: you can already imagine lurid headlines about piles of stinking rubbish being dug up in the face of opposition from irate residents.
“Digging up a landfill site can conjure up emotive images,” admits Andrew Turner. “That’s why it’s so important that we have a tool kit approach as a network. When a site is identified for a purpose how is the community engaged? Having worked in planning consultation I know there’s nothing worse than confusion or mystery. Helping the community understand why we are doing this and what the benefit is, is crucial.”
Which means putting in place an agreed code of practice before any excavation goes ahead. “At a local level, the communities are the ones that are going to be in and around it. How are we going to make sure that any odour is abated, that any dust or vibration is controlled before it’s allowed to escape the site? This goes back to the fact that it’s not simply about pulling up the cap, getting an excavator in and digging it out. There will need to be a stable, safe and secure way to excavate that material.”
It is inconceivable that any mining project would get the green light from the Environment Agency unless such safeguards are put in place: “There would need to be a good understanding of what is in the site – whether it’s household or industrial waste – from their site records,” says Turner. “Then safeguards in terms of an enclosed environment, taking material off site to specifically designed waste recovery plants and real time monitoring of what comes off in terms of odour and emissions. Plus a way of making sure that if there is exposure we’d be able to react to that and close the channels.”
Once approval has been given, the next stage would be to bore-hole the site to look at what exactly it contains. Only after that could excavation begin. “You’d need additional mechanical sorting processes, most probably trommel screening or eddy currents,” says Wagland. “If the site has the available space for it and it’s going to be a long project then it makes sense to put that equipment on site. Otherwise it would involve lorry loads going off somewhere else.”
How big this will be remains to be seen. There are over 22,000 landfill sites in the UK of which Wagland estimates “only a small fraction” would be suitable for landfill mining. “But even if we were to mine four or five sites, we would still be looking at several million tonnes, of which 30 per cent could be plastics and, say, another 10 per cent metals.”
“Obviously the older the site is the more likely you would find material that could be recovered. But those sites also pose different challenges – you might find things like coal ash or asbestos or chemical waste. It is an unknown – we don’t completely know what exactly might be in there.”
There has already been a landfill mine pilot site at Houthalen-Helchteren in Belgium. The Belgian waste management company, Group Machiels, has been excavating the site since 2014, which it hopes will result in 45 per cent of its 16.5 million tonnes being recycled over a 20 year period. The rest will be converted to a clean burning gas, with the residue from this being converted into a building material called Plasmarok.
A bright future
Turner argues that the UK is well placed to take advantage of the opportunity: “We have a strong pedigree in landfill science and engineering. We are going to need landfill gas experts, leach technicians and those who have experience of managing waste on an open site.”
“Then there is going to be a logistical element of bringing material in and out and technical engineering expertise – whether that be drilling, excavation or land remediation. There is going to be the science element – testing water, testing leeching, testing land, a planning element, a regulatory element and an engagement and communication element to this as well.”
Enhanced landfill mining is still very much at the drawing board stage but 2021 is proving to be a crucial year in terms of its development. A Steering Committee was founded in February with the mandate to create a roadmap to bring the idea into reality. Working groups are now exploring the pre-planning and regulatory work streams. The aim, Turner explains, is to eventually get the go-ahead from the EA for a pilot site. If that is successful, then further sites could be excavated by the middle of the decade.
Expect to hear much more about enhanced landfill mining in the coming years. “We firmly believe that there is a principle here that can support the UK to build back greener and build back better,” Turner insists. “We really are passionate about making this work.”