A CONTIGUOUS piled retaining wall installed by Van Elle to secure an unstable slope has doubled the usable area at an East Midlands site.
The 200m 2 embankment behind the Burton Road Auto Centre in Derby ran up to gardens at the rear of the property. The boundary needed the support of 80, 450mm diameter open auger piles to prepare for the removal of more than 200t of contaminated rubble.
A Klemm 709 rig and sectional flight auger drilled to depths of up to 10m through firm to stiff clay. A compact telescopic mini crane then lowered full depth reinforcement cages of 6, T32 bars into position.
Both pieces of plant were chosen because of site restrictions - the land is wedged between the gardens and Burton Road, a main route into Derby.
Van Elle engineer Chris Downs says: 'We used the Klemm 709 because it's self-contained, including a power source, and is a very stable rig. The piling platform was only 4m wide and the rig is 2.5m wide.' Because the water table was at 8m, the rig crews used a tremie pipe to install grout and displace the water in the bottom 2m of the holes.
Once the 50m capping beam had been cast and cured, redundant spoil was excavated and taken off site.
Van Elle completed the £110,000, seven-week job in December.