Resourceful with road waste
Published: 30 May, 2013
Local authorities are now capable of ‘cleaning up' in the cost reduction stakes when it comes to road sweepings and gulley waste by not just focusing on the cost effective machinery used to collect that material, but by looking at the bigger and more sustainable picture of recycling that material into a high value product, writes Mark Jennings Projects Manager for recycling firm CDEnviro.
The media constantly comments on the ability of the plant and machinery manufacturers to create the next generation of vehicles with which the waste industry can operate in a more efficient and economical manner. The recent Bauma trade show in Munich was no exception with many of the world leading equipment producers showcasing the latest technology with which operators can align themselves with the greener initiatives, not only in the UK, but also from Europe and the rest of the world.
Local authorities in the UK are also constantly striving to be more effective, focussing on the green agenda and exploring those advances in technology that are capable of creating that much needed step change. With eco technologies now available and driving the ability for large corporations to reduce their carbon footprint, machinery manufacturers have been working tirelessly to create new ranges of hybrid drive and operating systems that require less fuel and are more economical to run.
It is no surprise then that a company like Johnston Sweepers promotes its own technology through advertising as being ‘high performance with low fuel costs' (see cover shot of LAPV – March 2013). In addition other leaders in the highways maintenance vehicle markets are also advocating low carbon technology, hybrid fuel systems, savings on fuel costs, as well as enabling the user to work towards being more carbon neutral.
However, there is the train of thought that all these good intentions will amount to nought, as in the case of road sweepings and gulley waste, if the resultant material is either condemned to landfill, regardless of the cost effectiveness of the technology used to gather the resultant material, or in the worst case scenario, not collected at all.
In the UK each winter over two million tonnes of rock salt and grit is spread onto the road networks at a cost of over £150 million per annum, with the bulk of the material being used to treat motorways, trunk roads and main roads. Uncharacteristically for this time of the year gritting of the UKs highways continued well into April, resulting in a highly visible line of material that settles at the kerb channel as a ‘pink' smudge lining the highway.
The grit and salt that makes up this pink edge will then either remain on the road side where it settles undisturbed, or ends up in road side gullies where it will be removed by road sweepers. Either way the end result is the same. However, the majority of that waste product will eventually find its way to landfill, not a fitting end to a product collected by machinery using the latest hybrid technology. And of course the irony is that in the following year the Highways Agency will procure and spread another 2 million tonnes of material at a cost of £150 million which again will be spread on the highways and again be destined for landfill.
Many European countries currently recycle road grit to re-mix with salt for re-spreading. The UK can follow this lead and the technology is available now to recoup that wasted resource, protecting stocks of virgin aggregates. Recycling is high on the Government's agenda and with Landfill Tax set to escalate to £80 per tonne by 2014 the UK's Local authorities and borough councils are sitting on thousands of tonnes of a sustainable resource that can be diverted from landfill and returned to use as a high value material.
The size of this recyclable resource is unknown, with the exact volume a true mystery. The total amount of waste material that is recovered from road sweepings or the gully waste is only really known to the public sector agency that is responsible for its recovery. Local authority agencies work independently and are not required to share that data on the extent of the material that is going to landfill. In addition, it means that the potential volume of material that could be recycled and returned to the roads as gritting material is also unknown.
With 326 locally governed districts in the UK made up of Metropolitan Boroughs, London Boroughs, Non Metropolitan Districts and Unitary Authorities, some joined-up thinking could result in a more productive recycling initiative ultimately protecting the countryside from landfill whilst conserving virgin aggregate reserves. Information found on the Internet from the borough and district councils in the county of Leicestershire report that the approximate tonnage of road sweepings collected each year was close to 8,050 tonnes.
If a conservative average of 4,000 tonnes of road sweepings was taken across the 92 counties of the UK that would mean a possible total of 3.6 million tonnes of material going to land fill each year and at a cost of £50 per tonne that equates to £29.4 million for disposal alone, regardless of the collection costs.
Road sweepings and gully waste is an excellent source material for recycling. Whilst the saline constituent of the rock salt is dissolved and washed out, the grit and the aggregate material that remains is reclaimable and with the appropriate technology, approximately 90% to 98% of that material could be recycled and reused as a valuable resource.
From the conservative estimates of 3.6 million tonnes of material being collected by waste agencies and with sand or grit constituting 50% of the overall material recycled 1.8 million tonnes of grit could be made available each year to remix with rock salt for road use.
In addition, gully waste typically comprises of small stones, sand, gravel, ferrous material, paper litter and hydro carbon with organic matter mixed in. However, the main constituent of gully waste, is water. Water constitutes up to 60% of the total volume of this material which seems a ludicrous product to be sending to land fill!
One local authority that is leading the way in managing the recycling of road sweepings and gully waste is Warwickshire County Council who in the last 18 months initiated a recycling programme for material that previously had been sent to landfill. Now in collaboration with Coventry City Council, Staffordshire County Council, Solihull Borough Council, Worcestershire County Council and Leicestershire County Council, a joint working agreement has been entered into to recycle road sweepings and gully waste into a high value material.
In January 2012, working with CDEnviro, a 15 tonne-per hour road processing plant was commissioned for SITA UK Ltd at it's Neatchells Road depot in Wolverhampton. The plant incorporated a full water treatment system with the addition of several new design modules, a newly designed feed hopper and a high attrition system specifically designed to handle this heavily contaminated material.
The SITA facility has capacity to treat up to 40,000 tonnes of road sweepings and gully waste per year. During the life of the current seven year project in excess of 300,000 tonnes of material will be diverted from landfill, showing cashable savings of more than £10 million, increasing the projected increase of the overall material recycled in the county by in excess of 3%.
The resulting material being processed through the plant is now being used by Warwickshire Council in civil engineering projects as well as being remixed with rock salt for use on the highways in the winter months. The key objective of the programme was to see cost reductions in landfill tax across the region, whilst diverting waste from landfill and increasing the overall recycling rates within the region.
Cllr Alan Cockburn, Warwickshire County Council's Portfolio Holder for Sustainable Communities commented: 'This contract represents an excellent example of neighbouring councils working together to improve performance and save money. It will help boost our recycling performance by two or three percent and supports a more sustainable approach to waste management which benefits all residents.'