In an era when quarrying nationwide is becoming less urban-based, the presence of a former 60ha (150 acre) quarry within 30km of a major Australian capital city is rare – even in an infrastructure boom.
The Repurpose It site at Cooper Street, Epping, in Melbourne’s northern suburbs, is part of a once historic quarrying precinct that was as large as 526ha (1300 acres), encompassing the suburbs of Epping, Wollert and South Morang, and was excavated for its basalt reserves.
The exhausted quarries were converted to landfill cells and the land’s ownership reverted to the shire authority in the Whittlesea Council. In 2016, the council signed off on an ambitious plan – the Quarry Hills Precinct Structure – to convert 280ha of the precinct into parklands, commerce and housing, with 150ha deemed “net developable area”. The area could, in the long-term, accommodate as many as 2300 dwellings and a population of 6600.
In preparation for this transition, the Victorian Government has identified the Cooper Street precinct as a resource recovery hub. Repurpose It is considered an invaluable part of this hub. It operates in an old 60ha quarry that was never converted to landfill but is largely buffered by the old landfill cells, giving it 1.2km breathing space from the nearest residences.
The company has leased a good half of the site for a 20-year period – to run clean fill operations to remediate the old pits, while developing end products for reuse in infrastructure projects from excavation spoil, construction and demolition (C&D) materials, composts and other organic materials. A significant part of its operations include the commissioning of what is considered Australia’s first dedicated C&D waste washing plant for the production of manufactured sand and washed aggregates.
Repurpose It is a relatively new player in the Victorian recycled aggregates market, having been in operation for less than three years. In March this year, infrastructure and engineering services giant Downer purchased a 50 per cent shareholding in the company.
Repurpose It CEO and director George Hatzimanolis started the business after becoming fascinated by ways to reuse construction materials and reduce the construction industry’s dependence on extractive resources.
“I spent 15 years in the road construction and maintenance industry, mostly with Downer in their road surfacing business,” Hatzimanolis told Quarry. “I grew a passion for everything recycling about eight years ago when I started playing with substitute materials to extractive resources, trying to replace aggregates in sands and bitumen with residuals from recycling or other waste products. I was also introduced to materials like recycled toner from printing cartridges, using that as a polymer, waste glass as substitute sand, rubber to modify bitumen, industrial waste oils, recycled asphalt pavements. I really grew my passion for sustainability from that.”
Repurpose It began operating in 2017, and provides services and expertise in multiple transfer stations, waste management consulting, construction materials and soil amendments, organics and green waste processing, waste transport and collection, and importantly, its waste to resource operations.
It works with six main types of materials: green and organic; civil construction and infrastructure waste; excavation and demolition waste; municipal solid waste; solid inert waste; and drilling and drainage waste.
“Our business is designed around excavation spoil, in particular construction type of waste spoil,” Hatzimanolis said. “Anything that is generated from road or rail reserves is the type of waste stream that we handle and process – green or organic waste, soil, excavation rock or other forms of excavation spoil.”
Based in Epping, the company also performs contract work for local councils, including the shires of Manningham, Brimbank and Banyule. Repurpose It also operates under contract for Citywide Waste Management in West Melbourne. In 2016, Citywide opened Australia’s first street sweeping and pit cleaning recycling plant, which processes up to 22,000 tonnes per annum of the street sweepings waste stream, including grit, plastic, paper, cardboard, timber, litter and glass. These materials have been reused in standard road maintenance projects.
Repurpose It also partners with numerous civil construction companies, including Downer, John Holland, Eastern Plant Hire and Transurban, on projects across Victoria such as the Western Distributor, the Metro Tunnel and the Victorian Government’s Level Crossing Removal Project. A lot of the excavation spoil from these rail and road projects is inevitably delivered to Repurpose It for processing.
Materials quarries reject
Hatzimanolis says Repurpose It sits in the range of “materials that the other quarrying companies or crushing operations would reject. We’re about the materials that are too contaminated, with too high soil and clay content or other levels of inert or contaminated waste. We see ourselves as a service provider for the materials the quarries don’t typically process and we have invested in the technology to recover the resource from that, to ensure we’re optimising what can be recovered and reducing the industry’s reliance on extractive resources.
“Quarries are under immense pressure. Obviously, in a big infrastructure boom, the types of material we recover reduces some of that pressure. Our presence in the north of Melbourne, only 28km from the CBD, means we can offer our clients an efficient location to dispose of their spoil – and from that we pick up materials that we can recycle into sands, soil and aggregates.
“Our washing plant is designed to recover sand and aggregate particles from excavation spoil, so that is the predominant waste by volume that we process.”
The $8.5 million fixed washing plant, which has a footprint of 1000m2, is manufactured by CDE Global and comprises an Aggmax 250, a number of Infinity H2-60 horizontal sizing screens, a centrifuge for silt dewatering, and an AquaCycle thickening tank.
“It’s high pressure water attrition through the Aggmax, another set of rinsing screens washing the sand, and then water treatment,” Hatzimanolis said. “The washing plant itself can process, depending on the feed, anywhere between 150 and 250 tonnes per hour. It has an annual output of 500,000 tonnes.”
Hatzimanolis explained the decision to invest in a C&D waste washing plant came on the back of a lot of research at home and abroad. Repurpose It also had a prior relationship with CDE Enviro, the environmental division of the CDE Global business, through the establishment of the Citywide washing plant. This played a large part in the company’s decision to purchase the CDE washing plant for its Epping operations.
“We looked at seven or eight plants that CDE had built around the UK, and how that design had been refined and optimised, based on people’s learning and experiences,” he said. “We saw some nuances in a number of plants that some operators had imported into the design for their particular waste stream, and what we did was really take the best of what we saw for our set-up.
“We wanted to deal with a variety of waste, some heavily contaminated waste, some inert waste, where organics and other materials were going to be highly contaminated, as well as materials with really high levels of fines content. We also knew there was an opportunity in the hydroexcavation space around drilling muds, because sand and aggregate fractions can also be recovered from that material.
“So when we came up with our design, it was really taking the best of the CDE plants that we saw and adopting some smarts into the layout of the plant on our site, such as the range of the type of excavation waste, including hydroexcavation waste that we needed to build into the capability, and in particular being able to process some of the contaminated waste.”
At the time of writing, the washing plant had been operating for nearly four months, and Hatzimanolis said he was happy with how it was running.
“It’s a complex plant with a lot of moving parts and we’re dealing with a very variable type of waste stream – unlike a quarry that’s working on a particular reserve, or a crushing business with a waste stream of two or three products.
“We’re processing a very broad range of waste, so we probably put a fair bit of demand on the plant’s capabilities. That’s constantly requiring refinement. However, we’ve resourced the business pretty heavily from the technical point of view because that’s what’s needed when you’re running a complex plant across a variety of waste streams.
“The washing plant screens to a very consistent quality across fractions right from 0-2mm, 2-5mm, 5mm, 10mm, 14mm, 20mm and 50mm plus, so we can get good screen-fractionated material that can offer and meet the required particle size distribution of our specifications without further processing.”
The manufactured sand – generated by separating materials from particles 150mm minus in size – is being reused in concrete, asphalt, sand and aggregate replacement applications, and capping in landfill cells. Even the plant’s residuals still have a use.
“The percentage of recoverables depends on the incoming feed. Obviously, if we are washing something that is high in clay or silt content then we will get more residuals out of the thickening tank. Depending on how that material is classified, it still has a construction application as a structural fill, not as a sand aggregate. So there are applications for structural fill, and we have some customers who have been procuring that product. We also have a need for it ourselves as part of our quarry remediation.
“Typically, it’s a fine fraction, about 75 micron. It’s spadeable material, but does have good construction applications, and we’re doing a lot of work and research on that, some with universities, about other applications where it can be blended and value added to be used as structural fill.”
Rail ballast spoil from the Victorian Level Crossing Project is also a challenging product to wash. “The ballast that comes out of the washing process is only as good as the ballast that goes in,” Hatzimanolis said. “It’s about cleaning material, so where we can test our ballast and ensure that technically it’s suitable for reuse, our highest priority is to go for the best value reuse possible – preferably as rail ballast back on the rail network.
“We’ve had a lot of support and interest from VicTrack, MTM, V-Line and Yarra Valley Rail around the reuse of ballast and they’re now supplying ballast back once it’s been demonstrated it can meet spec. Where the ballast fraction is variable in its quality, then it will go out as other types of form. It still may be used as a ballast but on haul roads or as a drainage medium, rather than back on the road network.”
Repurpose It also accepts and washes recycled glass at fractions of 10mm minus down to 14mm minus. The glass arrives from other materials recycling facilities that have collected it as kerbside waste and processed it to a residual glass fraction that is unsuitable for a recycled glass application.
The challenge of processing glass fines is in successfully removing surface contaminants, which may include organics, plastics and non-ferrous materials.
“It can be very odorous, there’s bacteria issues, sugar, organics, molasses on the glass fines,” Hatzimanolis said. “Our process can scrub clean, through attrition and high pressure water, those glass particles, which means when it’s reused as a bedding material or by a contractor, it’s a more user-friendly material. Beyond that, we’re also looking at what end products we can devise with a cleaner fraction of glass. What’s the best possible reuse? Can it go back to glass manufacturing or can we use it to make other building materials?”
Low emissions footprint
In its publicity, Repurpose It has emphasised that the washing plant, for 100,000 tonnes of materials processed, has a low emissions footprint.
It generates 5000 tonnes of carbon dioxide per year – compared to the broader industry average of 22,000 tonnes of CO2 per annum. Hatzimanolis said the carbon emissions saving of 17,000 tonnes per annum is based on several factors.
“The emissions footprint depends on the total volume being washed, but we’ve had an independent life cycle assessment quantify our CO2 emissions profile,” he explained.
“On average, we can save about 168 kilograms of CO2 per tonne of material that’s diverted from landfill to our facility and the sands and aggregates reused.
“So the 168 kilos of CO2 per tonne with a capacity of 500,000 tonnes is about 84,000 tonnes of CO2 that can be diverted from the atmosphere each year through our facility. It’s quite a significant offset of CO2 in the market.
“We’ve looked at the total footprint and there’s a water usage component, as well as the plant’s power component. Quarrying can be quite energy-intensive in terms of fuels, and obviously there’s an impact of transporting those materials from quarries.
“Sand is a lot further away from markets than we are here at Epping. So our emissions footprint really looks at the whole impact. We see ourselves as an urban sand source and we are the closest source into the Melbourne market, being only 28km from the city. That presents an opportunity to use fewer trucks on the road and produce less CO2.”
In addition to running an environmentally friendlier operation, Repurpose It has enthusiastically engaged in research and development programs with statutory bodies, non-profit groups and universities to improve its end products.
In 2018 the company received a grant from Sustainability Victoria towards the development of the washing plant and it has also applied to have its products certified under the Green Building Council of Australia’s Green Star process.
In addition to partnering with RMIT to develop a clean glass fraction that can be reused in glass manufacturing, Repurpose It is also working with Swinburne University of Technology on the capabilities of its recycled aggregates and sands in a concrete application. Repurpose It also benefits from a National Association of Testing Authorities-approved on-site laboratory and a large Downer-owned R&D facility in nearby Somerton. Hatzimanolis says the company is working with standards authorities – such as VicRoads, the Australian Road Research Board, the Cement Industry Federation and the Infrastructure Sustainability Council of Australia – to update the specifications for acceptance of recyclable materials.
“A number of agencies are moving in the right direction, in particular VicRoads. In the last couple of years we’ve definitely seen a shift in their mentality about promoting the use and procurement of recycled materials, and that’s definitely helping businesses like ours invest.
“There’s still a lot more work to be done with some of the water authorities, which have quite outdated specifications around bedding materials. There are specifications that refer to sourcing from virgin quarry sources, which in our view is outdated.
“We are getting an audience and we’re starting to get traction but, like most big government bodies, the change doesn’t always happen at the pace at which the technology is moving. So that’s a challenge for the industry, not just Repurpose It. We need others to lobby with us to move things forward.”
Hatzimanolis is optimistic about the future of Repurpose It and its place in the recycled aggregates market.
He says the company has “ambitious growth objectives across the rest of the market in Victoria and beyond”, and he believes the business’ growth in the long-term will depend on “investments that mirror what we’ve done to find a niche in the market”.
“The premise of our business is about investing in best practice technology to convert typically untreatable waste into a resource, and really those are the values that will drive us forward,” Hatzimanolis said.
He predicts the company will continue to engage in a range of partnerships. He does not rule out working with other recycling groups where there is the “right business fit”, and with quarrying operations that are seeking to diversify into the recycled aggregates/waste to resources market.
“A lot of quarries have residual waste, scalps and other materials that they can’t process efficiently with conventional dry processing applications,” Hatzimanolis said.
“We have spoken with a few quarries about how our technology may be applied to them. We see ourselves as complementary to the quarrying industry, because we believe our materials can relieve some of their pressures.
“So we’re definitely open to partnerships where they make sense.”
First purpose-built wet processing plant
CDE Global supplied the equipment for Repurpose It’s C&D materials washing plant. It consists of an Aggmax 250, several Infinity H2-60 horizontal sizing screens, a centrifuge for silt dewatering, and an AquaCycle thickening tank.
“It’s a bespoke design,” CDE Global’s Australasian regional manager Dan Webber said. “We took George [Hatzmanolis] and his team to various CDE waste recycling plants, so they were very well informed and knew what they wanted and what they didn’t.
“In saying that, George put a lot of faith in our expert engineers and design team to develop a best in class plant. The key requirement was the design of a robust flowsheet that could make a myriad of products, as well as a highly efficient tailings management system.”
Webber agreed with the suggestion that the Repurpose It plant is indeed a “first” among the 40 CDE Global washing plants operating in Australia.
“This is our first dedicated C&D waste recycling plant in Australia,” he said. “Globally this is now a really important part of our business. With over 65 installed C&D plants across the world, CDE now has a dedicated ‘Reco’ business unit, so that we can further build on our success and develop new solutions in the construction, demolition and excavation recycling industry.”
Webber added that Repurpose It’s plant is also the “first purpose-built wet processing plant for the recycling of C&D waste in Australia. Other waste plants may dry screen materials or hand pick contaminants out but up to now wet processing was not used.
“The big difference between a wash plant for virgin material and C&D waste is that the feed material isn’t consistent,” he added. “The feed is usually very dirty – it’s high in clay and oversize – which means we need to carefully select the most effective equipment to treat the feed material.
“We usually incorporate some of our high tech scrubbing equipment – such as the AggMax logwasher – which cleans aggregates and frees sands bound up in clays. The other big difference is that a C&D waste recycling plant almost always has a dry tailings system set up at the back end. In this case, Repurpose It asked CDE to integrate our decanter centrifuge system.”
The feedback from Repurpose It about the initial performance of the plant – which began operating in March – has been positive. “Repurpose It has been excellent to deal with during commissioning,” Webber said. “They are really keen to learn how to operate and get the most out of the plant. They have thrown everything at it – some really challenging materials with large amounts of clay and oversize – and it has stood up brilliantly.”
Webber said CDE Global is likely to work again with Repurpose It and Downer Group. “I’d like to think that after our success with Repurpose It, along with the great plant that our sister company CDEnviro delivered to Downer in Sydney to reclaim materials for road sweepings, we are starting to build a great relationship.”