Morgan Est plc is nearing completion of the construction of three large diameter Storm Sewage Detention Tanks in Preston in the UK.

The 17.5m i.d. shafts were sunk as caissons to depths of 20m using bespoke precast concrete shaft rings. All of the storm tanks’ component parts, such as the shaft linings, central core flushing columns, roof beams and slabs, were precast at Morgan Est’s works in Ridham, Kent.

The company also carried out the shaft design in-house.

Ground dewatering was used when the shafts were being sunk and to resist the large uplift forces, an in-situ concrete base slab varying from 2m to 2.5m was cast in each shaft. The contract scope also included pump mains, pipework and overflow structures.