Balfour Beatty, in alliance with Anglian Water, is undertaking a new £1.8 million scheme to reduce the chance of bursts and leaks in the Framingham area of Norfolk by replacing existing water mains.
Already well underway, the current project phase involves laying over 11km of new water mains along the B1332 Shotesham Road, just south of Norwich, including other local areas of Bixley, Framingham Earl, Caistor St Edmunds and Porlingland.
What makes this project ground breaking is that Balfour Beatty is recycling all the excavated spoil material. This is done by treating it with SMR, the dry mix soil stabilisation additive provided by Richardson Recycling and SMR (UK) Ltd, then re-‐using it as an alternative sub-‐base material, diverting all the trench arisings from landfill.
SMR (Structural Material for Reinstatement) is fast gaining popularity within the utilities industry as well as with he highways departments of local authorities. Technically the SMR soil stabilisation process involves adding a specially formulated dry mix additive to excavated spoil, transforming it into a high quality recycled and reusable sub-‐base replacement within minutes. With typically 2% by volume of the SMR material being combined with excavated spoil, using mobile screeners and batch-‐mix equipment, the resulting chemical reaction dries out and stabilises the material for optimum compaction. The soil particles become bonded together, increasing the density and strength of the soil by as much as 600%, resulting in a high quality structural reinstatement material being created which consistently outperform traditional materials such as Type1 GSB.
Material from the trench excavations is collected by grab lorry and taken to Richardson Recycling’s local facility on a ‘tip & take’ basis. Here the spoil is screened to remove organic material and solids over 40mm in diameter, before being mixed with the SMR soil stabilisation powder. The resulting material is then returned to site by grab lorry where it is used as trench backfill and compacted in layers. The physical transformation is that under compaction the treated material adheres to the trench wall causing no shrinkage; stabilising the backfill which results in no block or beam effect.
Chris Taylor, Site Manager for Balfour Beatty comments “Working alongside Mick Damen, the Regional Reinstatement Manager for the @One Alliance who heads up this project, we had two priorities: Firstly reducing the carbon footprint of the job and being as sustainable as possibly. Secondly, on a high profile project such as this we could not risk any backfill shrinkage which would have affected the reinstatement, meaning future remedial works and returns to site. In all cases it is our policy to get it right first time. Also with such a large project, recycling as much of the material coming out of the ground as possible makes good economic and environmental sense. As part of Anglian Water’s @One Alliance team, we are looking to expand the use of SMR across all our projects. It is not just the sustainability angle that is attractive, SMR produces an exceptional product that is stable and compacts well, as well as returning a substantial saving on material costs.”
In circumstances that use traditional Type 1 sub-‐base material, all excavated spoil would have gone to landfill. The nearest depot to the Framingham project was the Cemex Flixton Park Quarry & Recycling facility near Bungay, a 40 km round trip away. Regardless of the financial savings made avoiding landfill, the Co² improvement on the project alone was quite startling.
The trench excavation was 600mm wide by 1100mm deep and 11 km long, equating to 7,260 m³ of material, which equals 10,164 tonnes. Transported by a fleet of 8m³lorries, this would have equated to 907 vehicle movements. With each movement being 40 km, the overall distance travelled would have been 36,300 km, resulting in a carbon rating of 31,740 Kg/Co², which equates to 31.74 tonnes of Co² all removed from this phase of the project, by using SMR as sub-‐base backfill thereby reducing the carbon footprint.
Cost comparisons on Type 1 and 2 roads, per 1000 metres for materials and tipping fees were calculated as follows:
(trench dimension: length 1000m x width 0.5m x depth 1m)
|Asphalt @£90 p/t
|MOT Type 1 @ £19 p/t
|Pipe Bedding @ £19 p/t
|Tipping Costs @ £12p/t – 0% recovery rate
(dimensions: length 1000m x width 0.5m x depth 1m)
|Asphalt @£90 p/t
|C$ NFSMR @ £27 p/t
|Pipe Bedding @ £19 p/t
|Tipping Costs @ £12p/t – 90% recovery rate
On the 11 km of trenches excavated for the new Framingham Earl water main, material savings of approximately £240,735 were made simply by adjusting the reinstatement specification. The SMR sub-‐base was layered to a depth of 650mm, as opposed to 465mm of MOT Type 1, thus reducing the thickness of both the asphalt base and wearing courses, resulting in a 40% overall saving in material costs.
The benefits of using SMR over conventional backfill are as follows:
“From April 2017, the UK landfill tax increased to a standard rate of £86.10 per tonne with an inert rate of £2.70 per tonne,” comments Andy Bareham, Technical Support Manager for SMR (UK) Ltd. “The actual cost of non-‐hazardous soil disposal also varies across the country, typically costing around £20 to £50 a tonne, with the cost of contaminated soil disposal being significantly higher. Transport costs further push the cost of disposing of waste material and with heavy diesel transport operators being increasingly penalised for inner city movements, reusing materials where they were excavated makes sound environmental sense.”
SMR (UK) is significantly increasing the number of locations around the UK where the technology is available to blend the SMR additive with excavated spoil, by growing its national network of recycling ‘HUB’ partners. Each ‘HUB’ has the necessary mobile screeners, Batch-Mix equipment and specially formulated additive, enabling them to offer their customers ready mixed and recycled sub-base from the excavated spoil.
For more information on the SMR soil stabiliser process or to find out the benefits of joining the growing national network of recycling ‘HUB’ partners either call 01252 710772 or visit www.smruk.com
Founded in 1999 SMR (UK) has developed and delivers one of the leading technologies to stabilise excavated spoil; cost effectively transforming it into high quality products that outperform traditional materials such as Type1 GSB and this can be reused on existing construction sites, therefore negating the need to send it to landfill.
With its HQ and automated manufacturing facility in Caldicot, Wales SMR provides a national Batch-Mix solution service that enables clients to meet challenging waste management compliance and landfill diversion targets plus decrease their carbon footprint.
The SMR(Structural Material for Reinstatement) soil stabiliser process involves adding a pecially formulated additive to excavated spoil that contains excess moisture, transforming it into a high quality recycled and reusable sub-‐base replacement within minutes. Typically around 2% of the SMR material is combined using mobile screeners and Batch-‐Mix equipment and the resulting chemical reaction ultimately dries out and stabilises excess moisture for optimum compaction. Soil particles are bonded together, increasing its density and strengthening the soil by as much as 600%, results in a high quality structural reinstatement material being created which consistently outperform traditional materials such as Type1 GSB.
SMR (UK) units 10&B, Norman Way, Severnbridge Industrial Estate, Portskewett, Caldicot, Monmouthshire NP26 5PT | Sales Hotline:01252 710772 www.smruk.com