Screening out contaminates to give soil a new lease of life

A suite of screens is helping Arletan keep up with demand for its land remediation processes as Ross Matthews finds out during on a trip to Wales.

Drive right to the end of the M4 motorway in Wales and there, in Carmarthen's Cwmgwili Valley, you will find a Recycling Village. Arletan's 40 acre landfill and recycling site is the largest privately owned waste recycling facility in Europe, managing waste from demolition, civil construction developments, local authorities and landscape gardeners.

When, in 2006, Eddie Court and his business partner bought an off the shelf company called Arletan and then the Cwmgwili site that was just being used for inert landfill they essentially started from scratch. A lot of hard work and development at the site has seen growth escalate in just two years.

While still taking inert landfill, today the site, christened by Arletan as a ‘Recycling Village' has two waste transfer stations, four different licenses for tipping and a fleet of new lorries. Arletan also has sites in Essex, where its head office is now located, and operates out of Manchester and Birmingham.

"If everything comes off as planned this year alone we will have £60 million of business on the books," says Eddie. "It's escalated that quickly."

Starting as a landfill and recycled aggregates business, the company is now using modern plant and machinery to recover, remediate and convert waste to aggregates, subsoils and topsoils for use in a vast range of building, construction and landscaping products.

The original objective for the Recycling Village was to recycle a minimum 85% of the aggregates and soils that pass through Arletan's hands, thereby reducing the need for landfill. Arletan then acquired the rights to land remediation technology from the US called Retekulation and this has been a key component the company's success as this process allows Arletan to recycle 100% of material.

Remediation is just one thing Arletan does. "We have an advantage over most waste firms in that we have so many different avenues because we have the licenses and planning for it," says Eddie.  "We can carry out works from land stabilisation to general muck shifting to supplying secondary aggregates as a one stop shop." 

The current state of the construction market is keeping the aggregates side of the business quiet. However, for the remediation and treatment packages Arletan gets at least two enquiries every day and is eyeing up some very major accounts.

Playing a vital role in the remediation process and helping keep pace with demand by facilitating the high throughputs required by Arletan's growing business is a set of mobile equipment supplied by Fintec.

Land remediation

Retekulation is used to treat soil from contaminated land either on-site or off-site at Arletan's licensed facilities. "We can treat most contaminants and the system has a 100 percent success rate," says Eddie. The process reduces a customer's need to buy in aggregates in order to replace dig and dump soils by allowing contaminated soil removed from site for treatment to be reinstated for a fraction of the cost of traditional methods. In all cases where this process has been used in the UK, the treated soil has been approved by local Environment Agency teams for re-use on-site, for instance, either as a paving base for roads and car parking or as structural backfill.

The company provides a ‘one-stop-shop' where initial site investigation, excavation, haulage to Arletan's site, decontamination and, if necessary, disposal can be taken care of in one place.

The suite of mobile machines Arletan uses for its remediation processes includes a Fintec 542 Tracked Screen, which on the day Hub visited South Wales, was busy at Arletan's Dagenham site treating organic materials from the 2012 London Olympics site, a Fintec 640 finger screen with two sets of fingers and an Extec Robotrac, which has been extended, making it a lot longer than other Robotracs. This allows the agents to be fed more efficiently. Dust suppression has also been added.

The Retekulation process essentially sees Arletan designing a mix of reagents to treat the contaminated soil. "Each mix is different and is designed to tackle the particular contaminants in the soil being treated," says Eddie. The mix is delivered to a silo, which feeds either the screen or the Robotrac to get the agents into the material. It's computer controlled to ensure the precise percentages required for the mix are delivered. "Our biggest challenge was how do we get these reagents into the material?" says Eddie, "Especially in Wales where you have particular problems with the clays. The most important thing about treating contaminants is that you need to get inside the smallest particle you can. We have found a way of doing that by adapting the mobile equipment."

Material may go through finger screen first, which removes the oversize material, leaving the lower fragments to be treated. "Where you have larger stones in contaminated soils, these stones are not necessarily contaminated, so we can screen them off so that we only need to treat the lower fragments," Eddie explains.

Material arriving directly from a soil wash can go straight through the Robotrac or the finger screen to get the reagent into it. "We can pick and choose, using whichever machine is more appropriate," says Eddie. "Every site is different; it could be down to available room, if we are working on a customer's site."

Speed is of the essence as well, especially with the equipment. Sometimes we can put through 2000 tonnes of contaminated soil a day - it can vary from a minimum of 75 tph. By the end of the day that soil will be treated. The recycled material is then stored on site or reused on site if carried out onsite.

"When we purchased the site there was an old screen here but it needed upgrading to handle aggregates so we purchased the Fintec 542 screen in June last year. Because of the service we had from Fintec and with the growth of our remediation service we bought another finger screen from them. We also bought the Extec Robotrac from them, and had it painted in Fintec Blue, which we've adopted as the colour of our machines.

Painting wasn't the only thing Fintec did for Arletan. The company was able to modify its machines to meet the precise needs requested by Arletan required for the Retekulation process.

"We've had these machines purposely designed to what we need and the service Fintec has given us is spot on," says Eddie. However, he's keeping these modifications under wraps as they play an important role in Arletan's process.

In addition to Retekulation, Arletan offers other remediation packages and these also involve the Fintec mobile equipment and the company is looking to purchase more machines as new contracts come on stream. "We have learned from using our equipment and have discovered that it would be beneficial to make a few more modifications, just to tweak them further to our needs and get an even better result and push more material through the equipment for a faster turnaround.

Happy customers

As mentioned earlier, Arletan has carried out work for the 2012 London Olympics site in East London. In addition to the organic material it is currently processing it has also taken filter cake from soil washers at the site back to Dagenham for treatment, before returning the material back to the Olympics site for reuse.

Eddie comments: "The filter cake came off their soil washers - soils from 90% of the site had to be washed. We treat the fine element where the contaminants are and turn it back into cementitious aggregate, which can go back for reuse on the site as general fill rather than go to landfill."

Eddie adds: "Some thought this couldn't be done but we proved it could and this has subsequently opened up a lot of doors for the company.  The process saves customers having to buy aggregates; they can reuse their soils and it diverts waste from landfill by recycling. We offer the whole package from plant hire, through to haulage."

Reusing materials is one of the biggest trends in the industry, according to Eddie. "It stops people importing natural quarry stone and all companies are being forced to go down the environmental route. So I think we have something better to offer in terms of sustainability than a lot of people realise. You only have to look at the landfill costs going up again for oil content material - it's nearly £900 per tonne."

Arletan is carrying out trials for another client that will lead to a significant new contract. Contaminated material hauled from this client's site is put through the Robotrac for treatment. The dark, coloured material going in is primary ‘claggy' filter cake with a high oil and iron content as well as a high moisture content of 68% plus. This would normally go to landfill.

"We needed to get the oil content down to 0.5% so the resultant product can be reused as back fill in furnaces and the iron salvaged," says Eddie. Once it has been treated it is dried and shipped back to the client.  "We do 500 tonnes a day," Eddie adds. "It takes a second day to cure before ending up with the dry product that can be reused. We've done something that is basically simple yet produced such a good end product," says Eddie.

This one waste stream for this client has led to Arletan signing up to deal with more waste streams and the company is just about to finalise a significant ten year contract.

During a tour round the Cwmgwili site we drive past the piles of treated material for resale. Pointing out one pile as an example, Eddie says: That came in from Ebbw Vale Steelworks as high TPH (Total Petroleum Hydrocarbon) material. We have an order for 10,000 tonnes of that to go out as a fill material to save the customer having to purchase aggregates."

Arletan has taken in Bentonite that will be used in a landfill cell in Swansea as Bentonite liner. "Where spent Bentonite would previously have been rendered useless because it has become wet, we can dry the moisture off and put it back into a form that can be reused to give it a second life," says Eddie.

Among other applications, Arletan treats dredged material and stabilises it for reuse. "We can carry out 300 tph and more if necessary."

The company is even getting enquiries from Kuwait's oil fields to help clean up Saddam Hussein's lingering mess.

Word is getting around very quickly about what these processes can achieve. "When we began I was chasing the markets like mad. Now they are coming to us, says Eddie. "The options are endless. We tend to go for individual client needs."

"The biggest problem I find, especially with the WAG (Waste Acceptance Guidelines) criteria, is getting local authorities to adapt to using recycled aggregates, which should be their policy. If recycled material meets the required specification then it shouldn't be a problem, but it's just a question of attitude. But it is still a growing market."

Indeed, Arletan is looking forward to a good year and hoping for good summer weather, as last year they were dealt a rough blow with the poor weather. "On average we get 75,000 tonnes in and 75,000 tonnes out every year. I think this year it could be double that," says Eddie.

Ongoing investment

As part of its ongoing investment Arletan is looking to invest in a soil washer. "This will be a mobile plant and will allow us to carry out contaminant treatment off site as well," says Eddie. The company also wants to put in a trommel and picking station for the C&D waste.

As Arletan signs up new contracts it will also be looking to increase its fleet of Fintec equipment. "We group all our mobile equipment as ‘suites of equipment' required to carry out a set amount of work," says Eddie. "A suite would be classed as a Robotrac, excavators, and the finger screen (we don't always uses both) and this suite of equipment will carry out a set amount of work. At the moment we run two suites. By the end of the year we will have ten suites."

 

What is Retekulation?

Redeveloping potentially contaminated brownfield sites is now a standard practice in construction and civil engineering and Retekulation is Arletan's fast deployment mobile service for this process. It can be applied to any project for on-site remediation, providing environmentally and economically sustainable development solutions for the future of construction.

Arletan takes samples of soil to be remediated and compare them with contaminated land data from hundreds of previously treated sites. The company then deploys its mobile equipment and techniques to the site. Treated soil stays on site, which reduces the customer's haulage and landfill costs.

Arletan licenses the Retekulation process developed in the US in mid-1980s. The process essentially mixes chemicals reagents and binding agents to eliminate the hazardous physical and chemical constituent properties to remove any environmental and health risk from the source material, whether its is organic, inorganic, sludge or dredge material - leaving no residual waste, creating a dry and environmentally safe bi-product that can be used as backfill or secondary aggregate safe for onsite or off site reuse. The secondary aggregate can be used on site for example as a paving base for roads or car parks. Since April 2008, site waste management plan regulations have been in force. Arletan can process hundreds of tonnes per hour per mobile unit.

A suite of mobile equipment to help Arletan keep up with demand

A combination of Fintec and Extec machinery - both companies part of the Sandvik Group - is helping Arletan keep up with demand. The Extec Robotrac track mounted scalping screen, employs a screening process that doubles as a grading screen in many applications. Designed to scalp the heaviest of material, it can also screen finer sizes. The machine's manoeuvrability allows it to be used in a variety of sites and applications. The unit is fitted with Extec's double deck vibrating grid and provides high speed scalping of sticky clay and fines from heavy rock and concrete. The heavy-duty impact feeder absorbs shock loads and maintains smooth flow of material to the stockpiling conveyor.

The Fintec 542 Tracked Screen is designed specifically for the recycling and Contractor market. It has a 3650 mm x 1500 mm two bearing screenbox with increased screening angle built into the bottom deck of the screen. This feature coupled with the larger screening surface area and increased throw on the screenbox enhances screening efficiency and capacity, through the actual screenbox itself.

The belt feeder has an 8 m³ capacity and is fitted with a radio controlled tipping reject grid as standard. A CAT 3054C water-cooled diesel 74 kW engine with an Engine Shut Down Protection System drives the machine. The main conveyor is fitted with a 1050 mm heavy-duty belt. The tracks are 500 mm wide to cater for various ground conditions and are pendant track controlled.

The Fintec 640 is a heavy duty scalping screen that can work as a stand alone three-way split screener. Constructed for easy mobility and transportation the unit's conveyors are hydraulically foldable and walkways are fixed, for quick transport and set up time on site. The screen can be feed by loading shovel, excavator or crusher The Hardox steel apron feeder provides a solution to aggressive applications and feeds directly on to the variable angle screenbox for maximum screening efficiency.

 

Extec Screens and Crushers Ltd
Hearthcote Road
Swadlincote
Derbyshire
DE11 9DU
UK

T: 01283 212121
http://www.extecscreens.com/