July 2024


True Grit

With the annual 1st April increase in Landfill Tax, and publication of guidance by the Environment Agency, there has never been a better time to investigate road sweeper and gully waste reprocessing systems says George Anderson, Director of the Siltbuster Group.

Since it was brought into existence in 1996, “with the intention of driving councils and companies towards the development of recycling infrastructure by making the landfill disposal route a more expensive and unattractive option”,  Landfill tax has steadily increased  by £8 per tonne per year, bringing the  rate for  active waste to landfill to £72 per tonne in 2013/14. This is set to rise to £80 per tonne in 2014, but from the start a lower tax rate for inert waste of £2.50 per tonne has existed.

Changes to the Status

In the past, the status of road sweepings and gully waste has not been completely clear. The European Waste Catalogue lists Street Cleansing Residues under waste code 20 03 03 as a non hazardous waste; yet the Environment Agency and the Highways Agency both agreed in 2010 that it should be potentially classified as hazardous. At the same time, many councils and waste contractors confused its non hazardous status with inert, sending the material to inert waste landfills at the lower tax rate.

This all changed on in May/June  2012 when HMRC announced that trommel fines, grits and screenings would no longer qualify for the lower  landfill tax rate, unless the materials complied with the Landfill Tax (Qualifying Materials) Order 2011.  To qualify for the lower tax rate, road sweeper and gully waste must be comprised of predominantly inert material (such as mineral, residual soil) with only small amounts of organic matter and other contaminants.  Given that the sweeper/gully waste typically contains 20 to 30% organic matter this clarification clearly signifies that the HMRC considers that these materials attract the higher landfill tax rate.

New Guidance

But May 2012 wasn’t all bad news, as the Environment Agency issued New Guidance on the Recovery of Street Sweepings and Gully Emptyings. This was produced for Waste Authorities in England and Wales to support accurate reporting for the Landfill Allowances and Trading Scheme (LATS) and laid out in black and white the do’s and don’ts of recovering the waste.

With this year’s increase in the Landfill Tax imminent, over one million tonnes of roadside and gully waste to be dealt with each year nationally, fledgling Environment Agency Guidance and the easy option of simply sending it to landfill now a much more expensive proposition, not surprisingly, local authorities are asking what’s the best way to deal with their road waste?

The answer is simple, look at what’s in it. The bulk of road sweepings and gully waste typically consists of recoverable, reuseable sand and gravel which can account for up to 60% to 75% of a local authority’s road waste harvest, with larger stones, fines, debris and litter, leaves, twigs and other organics making up the rest.  However it’s a variable and seasonal harvest too. Waste collected by road sweepers and gully suckers varies in both its content and consistency depending on the vehicle design, cleansing method, location, weather and time of year.  For this reason it has traditionally been a challenging waste stream to treat, so innovation has been the key.


Innovation has seen the development of, for instance, the Gritbuster System, a unique road waste washing and recycling system.  It is designed to cope with up to 10 to 15 tonnes per hour of such a variety of feed materials, it separates and dewaters the various recyclables and even recycles the water.

In essence, the processing starts with road sweepings and gully waste being tipped into the Gritbuster’s main reception hopper. From here, the material is transferred into a rotating trommel screen to be washed.  The material is then separated into over size material (+10mm) and the smaller (-10mm) fraction.

The oversize material typically contains larger gravel-like material and the usual road debris of bottles, cans, broken number plates, leaves and so forth.  Once separated, it is conveyed out of the machine.  The remaining material containing the sand, fine organics, silt and any other fines material falls through the trommel holes.  The fine organic matter and the coarse sand and gravel fraction are separated before each is dewatered and conveyed out of the unit as separate materials.

A second, finer grade of sand can also be produced by passing the material through a Siltbuster hydrocyclone and dewatering screen.  The resulting dirty wash water is cleaned in one of Siltbuster’s water treatment plants before it too is recycled.

All of this is done with a compact modular system.  The whole Gritbuster Washing & Recycling Plant can be squeezed into the corner of a council depot, operator’s yard or waste transfer station.

Financials & Targets

There’s a strong commercial imperative why it is worthwhile for councils to attempt to recycle such waste.  The 60% and 75% gravel and sand-sized particles, when reclaimed, can be put to beneficial use as a recycled aggregate for use in for instance low grade concrete production, pipe-bedding and other forms of secondary aggregate.  Thus the process turns what is a now, following the HMRC ruling, an expensive to dispose of waste, into a significant commercial, money saving opportunity.

In addition to this financial incentive, recycling road sweepings and gully waste provides a new recycling opportunity for local authorities – who with steep recycling targets to meet have to look for as yet untapped opportunities to ‘up’ their recycling game.  With a 50% recycling rate set for England by 2020 and an even more ambitious target of 70% by 2025 set for Wales, simply improving how they currently recycle isn’t enough.  Everyone is looking for new waste streams to focus on, and this one fits the bill neatly.

Defra has stated that where a local authority is responsible for waste collection and street cleansing under Section 89 (2) (a) of the Environmental Protection Act 1990, road waste is able to be included as part of the authority’s recycling targets.  So the 1 million tonnes of road sweepings and gully waste which currently go to landfill present a real, and as yet untapped, opportunity.


The Gritbuster System is currently being used by the private sector, including large road sweeper hire companies such as ADMEC Municipal Services Ltd., who installed a plant some three years ago. With changes to the cost of disposing of road sweeper and gully waste and ambitious recycling targets to meet, plus a tried and tested technical solution to hand, there has never been a better moment for the public sector to follow the private sector’s lead, and review the way it manages this waste stream.

To find out more about Gritbuster call George Anderson on 01600 772256.

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