Maximising productivity is paramount for any operator of expensive vehicles or plant. So when Hampshire-based R&W Civil Engineering found that it had to send road gully cleaning lorries on a daily 180-mile round trip to discharge at an accredited facility, it clearly had to find an alternative solution, reports LAPV.
The introduction of new EU regulations in 2012 dictated that it was no longer acceptable to send road sweepings, gully waste or other wet waste to landfill because of potentially high levels of hydrocarbons and other contaminants in the material.
But this resulted in the contractor responsible for the road sweeping and gully sucking contract in Hampshire sending its vehicles all the way to an accredited waste treatment centre in Dartford, Kent to discharge.
The additional 180-mile round trip meant shorter working shifts, long night journeys and significantly reduced productivity. It was also adding extra fuel and maintenance costs to the contract, adversely impacting the carbon footprint and placing added pressure on the drivers and vehicle operators.
As the tier-2 contractor ultimately responsible for the work, R&W Civil Engineering embarked upon a detailed consultation process to address the new environmental and logistical challenges.
After several years of trials and intensive research, all done in close collaboration with main contractor EM Highways, Highways England, environmental consultants MTS Environmental and the planning department of Hampshire County Council, a solution was agreed.
A bespoke, custom designed and built, environmentally accredited, waste transfer station was to be built and commissioned at the company's site in Hursley, Hampshire, to process locally collected waste. Not only would it have a positive environmental impact but building the plant would also improve productivity on the highways with many additional advantages for the local authority and other partners too.
'A gully emptier is an expensive, high performance, multi-purpose vehicle, so having much of its time spent trundling around the M25 either to empty it or drive it back to the next job just didn't makeeconomic sense,' said Natasha Hawkes, R&W's contracts manager and head of the Environmental Team.
'And with a variety of gully emptiers being used across the county, both on our projects and by other independent environmental services, construction and water contractors, the operating problems are exponentially increased.'
The new facility, which took just 16 weeks to complete, is now fully operational and draws on related wet waste processing technologies from various industry sectors including those used for treating water from vehicle wash plants. Also, because high volumes of contaminated water are involved that cannot just be disposed of (the treatment plant site in Hursley, near Winchester has no foul sewer connection), additional processes had to be incorporated.
The raw waste material collected is initially deposited from the gully emptier or tanker into a catch pit before entering a drainage run where it is channelled along a bespoke steel filtration gulley. It then passes into a two-stage settlement tank to separate solids and liquids.
From there, it passes to a full retention interceptor where the solid waste is extracted and held in spoil piles for reuse and disposal. The bespoke water treatment plant then processes the waste water. It first goes to an underground holding tank for oxygenation, then passes through eco-light cyclone micro-filtration before returning above ground into a holding tank for antibacterial treatment, by which time it is back to river quality.
The treated water achieves the COD (chemical oxygen demand) and BOD (biochemical oxygen demand) classification standards set by the Environment Agency.
Achieving suspended solid levels set to Southern Water standards also means no discharge consent is required, so the water could be returned to a river without causing environmental concern. However, in this instance, all the water is reused by the gully lorries for jetting highway drainage system, so there is no need to draw high volumes of potable water from the mains which adds to the environmental savings already achieved.
'Road gully and sweeping lorries typically require up to 2,000 litres of water in a single day,' said Hawkes.
'This water is normally drawn from the mains, putting pressure on domestic and commercial supplies. It is increasingly becoming a metered and valuable resource. With our new plant, the plan was always to reuse the water, recharging gully and sweeping lorries with the processed water for jetting highway drainage systems.
'This saves more than 1.5 million litres of fresh, clean water each year, diverting it from use on the highways and making it available for what it is intended ' drinking!'
The project has also resulted in around 7,500 tonnes of wet waste being diverted from landfill each year. Unfortunately, some of the collected solid material still has to go to landfill ' at a current cost of £80 a tonne ' but today this is only around 10% of all waste solids collected and typically comprises of unrecyclable solids and general roadside rubbish. The remaining 90% is processed in accordance with the EU regulations to BS3882.
This amounts to something approaching 60,000 tonnes of reprocessed material being produced and subsequently being reused as an all purpose topsoil on a range of civil engineering schemes across the Highways England and Local Authorities network, an agreement made with Highways England and Hampshire County Council.
'The most exciting aspect of this project is that it created a closedloop sustainable waste management system: waste comes in off the highway's network, is processed and then goes back onto the highways network,' said Hawkes.
'In addition to all its environmental and carbon reducing advantages ' which are increasingly important for local authorities and commercial companies alike, its positive impact on the people involved is significant and it also makes sound financial sense.
'The cost of constructing the gully waste recycling plant, like the one we previously had to use in Dartford, is typically in excess of £1.5 million. The complete R&W plant in Hursley was conceived and constructed using in-house expertise and equipment for around onefifth of that cost, representing fantastic value for money.'
In addition to the financial savings made by not sending the road sweepings and gulley waste to landfill, this system significantly reduces and potentially even eliminates the need to buy additional materials.
More importantly, the project has spawned a cultural change, instilling a strong ethos of collaboration and sustainability in the working community, with the recycling resources made available to the entire contract supply chain to use, including R&W competitors.
Now that the fully accredited wet waste treatment centre is operational in Highways England Area 3, the main highways contractor ' EM Highways ' has taken the road gully sweeping and clearing contract back in-house. Using its own fleet of gully suckers and road sweeping lorries, the company now has tighter financial control over the operation and has further reduced unnecessary travelling and increased overall productivity.
When asked what further difference this technology could make if the same approaches to handling gulley waste, water management, purification and recycling were adopted across the UK, Hawkes said: 'Savings could be substantial. Looking at water alone; if a county has just two road gully cleaning lorries operating 240 days a year and each vehicle consumes 2,000 litres of water daily ' this equivalent to 960,000 litres per year. With 83 counties in the UK this could be around 80 million litres, the equivalent to 32 Olympic-sized swimming pools.
'Factor in the savings in reduced landfill tax, not having to buy in the other reusable materials and the overarching environmental benefits and it's clear that more local authorities need to seriously look at this opportunity to realise savings, maximise their productivity and achieve the best possible return on investment.'