Dragados-Sisk Limmo Shaft (TBM Bentonite Plant)



Dragados-Sisk Joint Venture
Crossrail Project – Contract C305
London, England

20 m3/hr



  • Conceptual Design
  • Mechanical Engineering
  • Fabrication of all Equipment
  • Commissioning
  • On-Site Training and Site Support


  • Tornado 1200 Colloidal Mixer
  • 40’ Heated Container
  • 40 m3 Bentonite Holding Tank
  • One 100 m3 Capacity Bentonite Silo
  • Screw Conveyor
  • Automated PLC/MCC Control System
  • Air Compressor & Pneumatic System
  • Centrifugal Discharge/Agitation Pump

Dragados-Sisk JV was awarded the Crossrail C305 contract which entails three separate twin tunnel drives including the project’s longest drive, the 8.3 km push (Drive Y) from the Limmo Peninsula through Canary Wharf, Stepney Green, Whitechapel, Liverpool Street and finally arriving at Farringdon. The Project’s shortest drive (Drive G) will also launch from the Limmo Peninsula shaft and includes twin 930m tunnels to the Victoria Dock portal. Three Herrenknecht 7.08m diameter EPBM machines will be used.

Team Mixing designed and constructed a bentonite plant for use at the Limmo Peninsula site. The hydrated bentonite is used in the preparation of the “A” component grout to stabilize the grout and minimize the bleed. This is particularly important considering the long 8.3 km drives. The hydrated bentonite is also used for hyperbaric interventions (if required).

The plant incorporates a Tornado 1200 colloidal mixer for efficient mixing of the bentonite with water. The hydrated bentonite is stored in a 40 m3 holding tank built inside the 40’ shipping container. A centrifugal pump is used to discharge the bentonite to the grout plant as well as to agitate the tank contents.