Liverpool WwTW – Tank Replacement

Replacement of a collapsed Post Screen Sludge Holding Tank at Liverpool WwTW
United Utilities
Waste Water
July 2016
Eric Wright Water


The purpose of the Liverpool WwTW Sludge Holding Tank Replacement  Project was to demolish and replace an existing (though irreparably damaged) 2500m3 post screen sludge holding tank.

The original tank had crushed under atmospheric pressure due a failed (inwardly releasing) pressure release valve. Eric Wright Water Ltd was engaged in the capacity of Principal Contractor.

Phase 1 works included:

  • Detailed design (subcontract) and fabrication details for the new tank
  • All temporary works (incl. protection of adjacent client assets) and provision of access arrangements
  • Safe isolation works – all incoming and outgoing pipework / hoses / manifolds and removal of all telemetry components (reuse)
  • Sludge emptying / disposal followed by cleaning of the tank internals
  • Stripping of all mechanical and electrical equipment / assets
  • Demolition and disposal of the tank

Phase 2 works included:

  • Fabrication (by specialist subcontractor) and subsequent construction of a new steel / glass holding tank to clients specification
  • Civils work: new plinths, ducting for the installation, cabling chambers
  • Mechanical work: Installation of all required steelwork supports, pipework, hoses, manifold, valves, brackets, ducting and cabling
  • Re-installation of the air mixing system including testing and commissioning
  • LV distribution – supplies to equipment together with all insulation / grounding works
  • Recommissioning of the PLC SCADA / telemetry and return the system into service with liaison with the client’s representative and control team

Key Challenges

Establishing a safe working environment with (i) existing adjacent plant being protected with a crash barrier design scaffold and (ii) isolation of existing mechanical / electrical and process assets as part of the enabling phase.

The sludge process had to be diverted within temporary bypass pipework to allow the client to continue with its daily site operations.

Restricted working area for both access / the use of cranes to lift off existing equipment for re-use with lifting operations during the tank construction.

Added Value

Eric Wright Water completed the works on time, to budget and without any incidents / accidents or issues with process safety or adverse effects to the adjacent client infrastructure.

The Project Management team on site undertook this project in parallel with another contract on the Liverpool WwTW site and consequently savings in management costs were realised by the client.

Get in Touch

For all enquiries, please get in touch with the team here at Eric Wright.