Victoria’s reliance on extractive resources is increasingly becoming an unviable prospect, but a new solution will soon see more construction and demolition materials recovered in the state.
Victoria has had the advantage of raw earth resources that have met the needs of the prosperous construction industry for decades on end.
According to the first-ever Extractive Resources Strategy, around 535 quarries within the state produce 50 million tonnes of stone, limestone, gypsum, sand and gravel each year. The 2018 strategy shows demand for extractive resources is at an all-time high due to population growth and a ramp-up in major infrastructure projects.
But emerging shortfalls in the supply of extractive resources is creating an urgent need for the government to secure high quality resources needed to meet Victoria’s current and future infrastructure plans. According to the strategy, a failure to do so within close proximity to growth areas and infrastructure will likely increase the cost of constructing houses and infrastructure.
As a result of Melbourne’s infrastructure boom, the city’s landfills are also under pressure with significant amounts of excavated materials being buried in landfill. According to the 2015-16 Victorian Recycling Industry Annual Report, aggregates, masonry and soils make up 22.8 per cent of all landfilled materials.
Fortunately, the amount of materials being reprocessed has increased by three per cent to recover 4.1 million tonnes of aggregates, masonry and soil material.
However, when the 4.1 million tonnes is broken down by weight, the composition of recovered materials encompasses just over 50 per cent concrete. The remaining composition covers a few other areas, but recovered soil/sand is only two per cent, mixed aggregates, masonry and soils make up 14 per cent and rock/excavation stone 11 per cent.
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Relying on virgin resources means mining Australian quarries and using valuable resources, which consumes energy and can cause pollution. Furthermore, more than 900,000 tonnes of construction and demolition materials are being landfilled each year.
With quarries being pushed further out due to the urban sprawl, trucks on the road are increasing due to the vast distances required to transport materials, thereby raising Australia’s carbon dioxide (CO2) emissions footprint.
FINITE RESOURCES
George Hatzimanolis carries 15 years in the civil works and construction industry and has been well aware of these issues. This knowledge prompted he and four other business partners to establish Repurpose It in March 2017 – a resource recovery business founded on industrial ecology.
“My personal view is that in the long term, there has got to be a better way than building our infrastructure with resources that we know are finite and precious,” George explains.
George says that C&D waste has been traditionally difficult to treat due to the mix of contaminants.
“We looked at countries around the world that have less extractive resources available to them and asked: how do they deal with this issue?” George explains.
“What we found in other parts of the world was that manufactured sand was fairly prominent to replace virgin sand and we started looking at technologies around that.”
Repurpose It’s research led it to a UK supplier known as CDE Global – manufacturers in mineral processing and extractive resourcing. The company identified its C&D processing facility, used extensively in the UK, Germany, Norway and Sweden and other countries, as well equipped to process materials in Australia after an extensive study tour overseas in early 2017.
Leveraging a 150-acre former quarry site owned by the business’ directors, Repurpose It last year began planning the nation’s first construction and demolition washing plant set to be operational by the end of 2018.
Its Epping site in Melbourne was considered the ideal location due to its proximity to the city via the freeway and closeness to major infrastructure projects. The Cooper St West precinct, in which the site sits, has also been identified by Sustainability Victoria in the 2018 Metropolitan Waste and Resource Recovery Implementation Plan as a significant hub for reprocessing materials from C&D activities.
After establishing a best practice technology, the company applied for a $500,000 grant through Sustainability Victoria’s Resource Recovery Infrastructure Fund and was successful.
THE CAPABILITIES
The new C&D washing facility is capable of processing up to 250 tonnes per hour and will be able to accept a variety of waste streams, from traditional excavation waste such as rock, sand and silt, to waste mixed with other manmade inert materials, including concrete, grit and rail ballast. The plant will also be configured to handle non-destructive drilling and drainage waste, in addition to drainage waste and dirty glass. “All those will be used to make a variety of materials that will replace virgin materials, predominately manufactured sand as well as washed and cleaned aggregates that will go back to other construction materials,” George says.
He adds the materials will then be reused as concrete, asphalt, sand and aggregate replacement applications and capping at landfill cells.
“We’ve also done a lot of work getting some engagement across large infrastructure projects, including the Western Distributor, Metro Tunnel and level crossing removal projects in their spoil disposal to help contractors achieve their sustainability targets,” George says.
He says independent lifecycle modelling has identified the C&D washing plant has potential to save more than 80,000 tonnes of CO2 emissions per annum.
The first part of the process involves separating materials from 150 millimetres in particle size. Metals are recovered under a conveyor with a magnet. From there, the material goes into wet processing with intensive washing and scrubbing under high-pressure. Any larger particles greater than five millimetres are scrubbed and separated by density using forced floatation, including organics, paper and plastic.
Aggregates are scrubbed, screened and washed again, then screened and fractionated according to the end material specification required. Sand particles and any materials less than five millimetres in size go through a cyclonic sand washing process where they are separated over another wet screen to two different fractions of zero to three and three to five millimetres.
“We can also then blend it to meet different particle sizes within certain specifications of our sand. So we will be able to meet a variety of different sand specifications through this type of technology,” George says.
“We don’t anticipate the residuals to be more than 20 per cent based on all the technical research we’ve done. We’ve been testing a lot of the potential feedstocks for this plant over the last 18 months with significant research and development into the types of materials available in the market.”
FURTHER RESEARCH
Repurpose It is currently working with Melbourne’s Swinburne University with a research project underway to test manufactured sand in construction applications. George says work has also been conducted with the Australian Road Research Board in addition to Vicroads to update the specifications around the treatment of manufactured sand.
“I think there’s a lot more work to do in that space around getting some of these outdated specifications upgraded in particular where virgin materials are mandated,” he says.
He says Repurpose It is also working to get its materials certified under Green Building Council of Australia’s Green Star process.
“We need to make sure there’s continued growth in procurement around recycled products, but we are seeing a strong uptake compared to what we’ve seen before – hence we feel our timing is right with this investment,” George says.
He says the facility’s ability to use washing and forced floatation offers potential across other waste streams, including waste plastics and more advanced washing and scrubbing of glass followed by the next phase of water treatment.
With the new C&D facility almost operational, Repurpose It is already looking at next steps for the future. The facility’s electricity use has prompted the company to look at renewable energy to reduce its carbon footprint in that area. It is also looking at a new innovative process for organics and commercial food waste.
“Our view is a lot of the materials utilised to build our critical infrastructure are perpetual.
“All of them can be recovered and reused with the right technology and that is the space in which we are are investing,” George says.
