A UNIQUE piling rig saved principal contractor Lemmeleg thousands of pounds and weeks of additional labour time on a Rochdale project in March.
Subcontractor Pennine had finished vibrocompaction works at the Milnrow site, where a cladded steel framed ink manufacturing plant is being built for Sun Chemicals.
But just as Lemmeleg had almost completed building work, Sun Chemicals added a new requirement to increase floor slab loadings from 40kN/m 2 to 75kN/m 2 to accommodate additional tank holders not originally planned for.
This meant either removing the floor slab and up to 3.5m of made ground and importing and compacting hundreds of tonnes of granular material - which could have undermined the foundations - or partially dismantling the newly erected building to make room for a standard vibro rig.
Pennine operations manager Mike Moxon said: 'We used our Tardis vibro rig which eradicated the need for dismantling. It has a safe working height of 7m, enabling installation of vibro columns to a depth of up to 5m and can extend or retract its mast to accommodate different treatment depths.' Originally 264, 3.5m deep columns had been installed through the made ground into terrace gravel below. Site workers took three days to install an extra 146 stone columns to depths of 3-3.5m.
David Akitt, project manager for Lemmeleg, said the Tardis solution had saved thousands of pounds in removal of spoil from the site.
'Stripping off the cladding and taking down the steel frame, or excavating and removing hundreds of tonnes of material would have delayed us by up to 20 weeks - and cost in excess of £150,000' he said.