Civil Engineering


M80 Filter Drain Recycling

Junctions 5-7

Carnell worked in collaboration with BEAR Scotland, the maintenance contractor for Highway Management (Scotland) Ltd who operate and maintain Transport Scotland’s M80 DBFO, to undertake filter drain refurbishment between junctions 5&7 in June 2023.

Using the StoneMaster process to recycle the filter drain media in-situ, provided several carbon, safety and road user benefits over the traditional dig-out and replace method. In addition, the innovative SmartScan survey which took place in advance, identified the areas most in need of attention, enabling a targeted solution.

The 2,800m length of filter drain was brought back to specification in 9 night shifts. By only taking away non-compliant material, 420 lorry journeys were removed from the network, while the reduction of materials, haulage and waste disposal led to a reduction in CO2e emissions of over 28 tonnes.

Using StoneMaster on the M80 to recycle the filter drain in-situ resulted in:

  • 2,800m of safer road.
  • Re-use of 2,282 tonnes of aggregate. (As heavy as 20 blue whales).
  • 5,736 fewer HGV miles transporting materials (A distance longer than the Great Wall of China). 
  • Reduction of 15,049m3 CO2e. (The same volume as 6 hot air balloons).

Resilient roads through a sustainable process

In producing a fully functioning filter drain which will extend the life of the carriageway, StoneMaster removed a tonne of non-compliant material every 7.1 linear metres of filter drain. This is what fills the voids in the filter media, reducing the drains effectiveness.

Safety was improved through reduced roadworker exposure, while the risk to road users was minimised through an 82% reduction in lorry movements in and out of the work zone.

The StoneMaster process is resilient in the face of high fuel and aggregate prices and the shortage of HGV drivers.

Mission Zero

  • StoneMaster significantly reduces the production of green house gases (CO2e), therefore supporting Mission Zero and the ambitious target to reduce transport carbon emissions by 75% by 2030.
  • All reusable material is returned to the drain, with only the silt and fines removed from site.

Think Safe, Home Safe

  • Filter drain maintenance supports the Climate Change Risk Assessment for Scotland, as we expect to see ‘increased rainfall on the wettest days of the year’.
  • Better drainage means improved safety for road users as water is effectively removed from the surface, minimising risk.