Retaining wall designer and contractor Phi Group's Soil Panel RS system is supporting the embankment and raised areas for access roads and car parking at a new business park at Burnden Park, Bolton.
The firm, working for client developer Emerson Group and its consultant Modus Consulting Engineers (now Sinclair, Knight, Morg), proposed the system after traditional embankment slopes of 1 in 2 were rejected because they took up too much space.
The site is underlain by variable fill to significant depth, which meant there was a risk of differential settlement.The solution had to minimise this risk and be able to absorb some movement, which effectively ruled out 'hard' options. The client also wanted a natural looking vegetated slope to reduce the impact of the walls.
Reinforced soil was chosen because there were large amounts of granular demolition material (mainly crushed concrete) on site. The Soil Panel RS system was used to form the slope with a face of 2 to 1, because it allowed the line of the slope to be controlled, can absorb differential settlement and has a panel of topsoil across the face to support vegetation.
The eight-week contract began last September. In all, 1100m 2of reinforced earth embankment up to 5.5m high was built by main contractor PE Jones Contracts (Manchester) - a member of the Emerson Group - which supplied the granular demolition fill and used imported stone when necessary.
The front face was topsoiled and seeded. Germination and greening of the face began as the work progressed and it is now well covered with vegetation.