Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to the newest version of your browser.

Your browser appears to have cookies disabled. For the best experience of Construction News, please enable cookies in your browser.

Welcome to the Construction News site. As we have relaunched, you will have to sign in once now and agree for us to use cookies, so you won't need to log in each time you visit our site.
Learn more

The mobile alternative to settlement tanks

PLANT HIRE - The Siltbuster is fast becoming de rigeur on sites. Andrew Barker delves as deeply as he dare into the murky world of settlement tanks

THERE cannot be too many equipment suppliers that claim an in-depth knowledge of fluid dynamics and sedimentation. But for the trio of engineers behind the Siltbuster portable settlement tank, knowledge of particle physics led them to design a product they claim can perform the job of 10-20 static tanks. And it is a lot less cumbersome than digging a settlement lagoon.

'The days of a skip and straw bales are long gone now, ' says Siltbuster managing director Richard Coulton.

The machines are 'plug and play' tanks of various shapes that run off an external pump with no need for an extra power source. But that's not the only environmental plus. The Siltbuster has myriad applications for restoring water to a suitable state for discharge into the environment.

The treatment of site run-off forms a large part of the firm's business but the units have also been used for groundwater treatment, drilling and piling operations and sewage work.

For sewage work, a Siltbuster is of particular importance, George Anderson, another director, explains. 'In an urban setting you need to remove the gross solids to return the water to the sewer and meet the requirements of the Environment Agency, ' he says.

The 'working heart' of the un its, according to Mr Coulton, is in the arrangement of impervious plastic boards upon which fine particles settle and slide to the bottom of the tank. The boards divide the flow into a number of channels, maximising the surface area of water that comes into contact with the boards.

The concept has been around for a long time but where they identified a gap in the market was in making such technology both portable and user-friendly. Testament to the Siltbuster's durability is the figure Mr Coulton proudly stumps up: that just one board out of 20,000, in more than 400 projects, has needed replacing.

Mr Anderson believes it is not just the quality of the products that has contributed to the success of Siltbuster. Their speedy delivery service also plays a vital part, considering the day-today unpredictability of a construction site and increasingly stringent pieces of green legislation.

The original design, known as the FB50, is continually evolving and a recent development is a surface-collecting arm that makes it suitable for separating oil. A new addition to the fleet is the mobile filter press, which will compact the settled particles into solid cakes - a good option when there is nowhere suitable to discharge if the material is contaminated and therefore needs to be removed so as to comply with landf ill legislat ion.

The FB50 has been on the market since May 2003. A professor of environmental engineering tested it at Cardiff University and a patent soon followed. 'A fair bit of R&D and intellectual muscle got it to where it's at, ' Mr Coulton says.

He came up with the idea while work ing in mining. In fact, all three directors previously worked as mine engineers in Ashford, Kent, and a specialism of theirs was liquid-solid separation.

'There's a lot of dissolved metals in mine water. You have to take them out of the solut ion to form particles and then settle them out. It's the second part of this process that we have exper ience with, ' says Mr Anderson.

Taking that knowledge and technology from the mining industry, they adapted it for construction.

It was by no means a case of a Eureka moment, more of an at tempt to come up with a system that could meet the imminent demand for a more sophisticated alternative to settlement tanks.

But Siltbusters is not simply about the tanks. Full technical support is offered as part of the package on offer. In spite of the environmentally conscious climate in which the industry finds itself, Mr Coulton believes technical knowledge of water treatment leaves a lot to be desired among industry workers and management.

He says they are hatching a plan to offer silt management training courses (which doubtless will cause some teasing of potential delegates).

'A lot of people simply don't understand the difference in particle sizes. If we can raise awareness of the legal constraints and how the materials work, it will make our lives much easier.'

Upon a new enquiry, the first question they ask is: does the particle matter sink or float? From this information they can gain a pretty good idea of what they are dealing with - but sometimes simple scientific principles are not enough, says Mr Coulton.

'When you look at the physics of the settlement of clays, you need to add chemicals to encourage particles to aggregate together. We play around with chemistry, adding coagulants and flocculents to make stuff settle.' This takes place at Siltbuster HQ in Monmouthshire.

What they have found is most enquiries are from repeat business. The contractors tend to take Siltbuster with them from job to job and for this reason they are in the fortuitous position of not actually having to chase business at the moment. But they are well aware th is luxury won't last forever. 'There are a large number of contractors that aren't converts yet and we need to get to those, ' says Mr Anderson.

Still, they can already cite a host of big names buying into their products, such as Balfour Beatty, Galliford Try and Sir Robert MacAlpine. At one point a couple of years ago they found their entire hire fleet was at Terminal 5. Although admittedly it was only 30 units at that time.

The fleet is constantly in 'a state of flux', according to Mr Coulton, because clients are prone to purchasing the machines once they have tested them out. As it stands, the fleet is about 180 strong. But they are planning to double this in the next six months to meet demand.

The expansion is well-timed because the Environment Agency is expected to introduce a new regime in April '07, which will, for the first time, require contractors to be licensed to dewater on-site. After this predicted national boom, Siltbuster has set its sights globally.

'There's a huge scope for breaking into the market on the Continent. We've sold half a dozen to Australia already but that was different, we speak the same language, ' says Mr Anderson.