The project involved replacing a 5m high 70m long section of dry stone retaining wall that had, through a combination of age and weathering, reached the end of its working life. Beneath the wall was a further 5m deep of fill and two old stone arch culverts through which a stream flowed under the road.

Richard Kromolicki from Tameside MBC explains: "The stone culvert presented us with a real problem because of its age which meant we had to be careful not to overload it with heavy fill material. Fillmaster was ideal because it is so lightweight, yet is extremely strong and proved to be very easy to handle on site."

The existing dry stone wall was replaced with a reinforced concrete 'L' shaped cantilever wall to give the 5m high structure sufficient strength. Traditional fill was used in areas away from the stone culvert with all the work being carried out by A&E Yates, the main contractors on the project.

The old age of the stone culvert meant that it was not possible to use traditional fill along a 20m section of the wall.

Fillmaster was specified in these areas because it reduced the loading on the stone culverts, whilst being strong enough to enable a balancing top layer of fill to be used. A stepped 1.8m layer of Fillmaster high strength FM500 grade was used directly above the culvert, with an additional layer of fill placed over the top. This combination of Fillmaster and traditional fill reduced the downward pressure on the culvert , whilst the stepped arrangement back from the wall reduced the lateral forces against it.

Traditional fill materials can cause unacceptable vertical and/or horizontal stresses in vulnerable underlying soil and structures. The use of Fillmaster expanded polystyrene offers a reliable, cost effective and lightweight solution to these problems.

Fillmaster is suitable for a wide range of applications from landscaping applications, through to road construction, retaining walls, rail and bridge embankments and noise bunds. The product is HCFC-free, non-toxic and fully recyclable.