Tuesday, 27 January 2015 10:04

Salt road grit and gulley waste should be recycled more

At this freezing time of year, the Highways Agency again focuses its attention on keeping roads clear and ensuring sufficient supplies of road grit are available for spreading on the UK's carriageways. With over two million tonnes of rock salt and grit spread onto the road networks at a cost of over £150 million each year, it is with regret that in the last 12 months over one million tonnes of road sweepings and gully waste will have gone to landfill at a cost of £80 per tonne in landfill tax alone.

road sweepings2 copyWas the Government's Landfill Tax not imposed as a deterrent to dumping? Are we not wasting a valuable resource that could be recycled?

UK Plc has moved ahead in leaps and bounds when it comes to improving efficiency in the recycling of waste material over recent years but there is still valuable material that, with a little capital expenditure, could be diverted away from landfill and make a significant difference to highways across the UK. Here Peter Craven from CDEnviro, recyclers and washers of waste materials, comments on why road sweepings and gully waste recycling should be moved up the environmental agenda.

The revised Waste Framework Directive (rWFD) already has stringent recycling targets to be achieved by the end of this decade but new proposals from the European Commission, unveiled in July 2014, if adopted, set the bar even higher.

By 2030 we can expect to have to recycle 70% of all household waste (we currently achieve just over 40%) and there would be a total ban on sending waste to landfill that could have been recycled.

Road sweepings and gully waste may not initially look like a viable source of recyclable material, however, all the constituent parts have value, and this material is a prime example of a waste stream that's not currently being maximised.

road sweepings Aggregate copyThe saline constituent of what's spread on the roads is ultimately washed out but the grit and aggregate materials are reclaimable. Around half of the overall weight of gully and road waste, when collected, is typically water. When washed and dewatered the sand and grit element accounts for around 50% of the overall volume.

Larger aggregates comprise a further 40%, with the remaining 10% being organic and other lightweight waste. This organic content can fluctuate significantly due to seasonal influences. During the spring and summer pollen and grass cuttings are particularly evident while the autumn sees large volumes of leaves being included.

Unfortunately resistances to recycling and the preference to send road sweepings and gully waste to landfill may, until recently, have been influenced by the Environment Agency's policy on street cleansing and leaf collections.

This reports organics cannot be used to produce compost because of contaminants. With high levels of hydrocarbons found in the organic material, road sweepings and gully waste are not listed in the Compost Quality Protocol. The result is that the feedstock is downgraded to Compost-Like Output which means the material remains as a waste product.

road sweepings mr craven copyUnder pressure to increase recycling in more innovative areas and with advances in screening technology that sees impurities being removed, the Environment Agency is waking up to the fact that this form of recycling represents a good stream of valuable material. Many local authorities are also now seeing the benefits of recycling over landfill.

How big is this recycling opportunity? How much waste material could be returned each year? – Actually, nobody is really sure as there appears to be little joined up thinking! No single agency is in control of all aspects of collection and therefore statistics are sketchy at best. Conservative estimates suggest between 650,000 and 800,000 tonnes per year are recovered and could be recycled, creating a welcome resource stream.

In addition to reclaiming the grit, the larger aggregates could be reclaimed for either pipe bedding, road construction or used for manufacturing concrete. The finer material can be used as a soil substitute for reclamation, restoration and land improvement. The organics can be sent to composting. Recovering material from road sweepings and gully waste does not only provide a sustainable long-term solution for the waste material but helps organisations increase their recycling ratios, while offering significant economical savings.

A flagship project set up by Warwickshire County Council in the West Midlands in 2012 embraced the guidance and technology available, and encouraged a number of local authorities to collaborate and share technology with a view to creating sustainable solutions to recycle road grit and gully waste. Over 300,000 tonnes of waste material will, over a seven year period, be diverted from landfill, whilst delivering savings of £10 million, boosting the recycling rates of the participating authorities by around 3%.

Despite the motivation to improve recycling, why is the volume of recycled gully waste and road sweepings not higher?

CDEnviro's Peter Craven puts forward a number of reasons for this. Firstly, there may be nervousness from operators to fully embrace this resource as a commercial entity. There may also be a lack of education and awareness. More likely is the complex nature of the material and a lack of understanding of the extremely good technology that now exists in the UK to process this waste.

road sweepings1The UK is behind the curve when compared to Europe there has been some movement in the case of sweepings and gully waste over the last 12 months but more work and awareness is required to get other authorities to embrace this initiative.

Environmental legislation is only going to get tougher and the cost of landfill ever more expensive. The publication of 'Recovery of Street Sweepings & Gully Emptyings' by the Environment Agency now clarifies the types of waste that qualifies as being non-hazardous as well as outlining disposal routes.

Innovation in recycling is key and local councils and commercial organisations must look to reduce waste and save costs. Road sweepings and gully waste offers that opportunity and it is a step in the right direction in helping reduce environmental impact and meet future requirements.

CDEnviro is the environmental recycling arm of CDE Global. CDEnviro has developed technology to reclaim this valuable resource that can be reused in the gritting of the UK's winter roads or can be diverted to other areas of the construction industry as a high value material.

'Recovery of Street Sweepings...'