SITA UK Ltd have developed an existing 2700m2 warehouse building at Ridham Dock, Kent, for use as a processing plant to generate up to 950T per day of solid recovered fuel from commercial paper and plastic waste which required a Piled Floor Slab solution. This processing involves shredding, drying, metal and ceramics recovery, baling and wrapping. The equipment train imposes point loads of up to 187KN and each item of plant must be located within tight relative tolerances. There are substantial loadings from HGVs and front end loaders. The existing 1970s floor slab comprised thin concrete over 12m of soft alluvial soils and was inadequate for the proposed loadings.

Working to a deadline imposed by the plant delivery programme, Peter Baxter Associates commissioned a quick and economic site investigation using a rig mounted dynamic cone penetrometer, to determine the depth and strength of the underlying London Clay. A piled floor slab was designed based on segmented precast concrete piles at 3m spacings. The load analysis was carried out using a finite element technique, and two discrete high load areas were increased in thickness. The slab was generally 270mm thick reinforced concrete C50 DS4 power floated, and cast in three areas.

Peter Baxter Associates prepared tender documents based on the NEC Option B contract form, reviewed pile calculations and other contractor’s submissions, and supervised the works. The works commenced 12th December 2011 and were completed in February 2012. The plant became fully operational in August 2012.