AECOM has been awarded a multi-million-pound design-build contract by Galliford Costain Atkins (GCA), as part of the AMP5 £200 million extension to United Utilities’ Liverpool Wastewater Treatment Works.

AECOM’s unique Cyclic Activated Sludge System (CASSTM) SBR technology has been selected to treat the flow from a catchment serving a population equivalent of 600,000 people.

 AECOM is providing design, supply, installation and commissioning services for the new two-storey sequenced batch reactor (SBR) being built in Wellington Dock. The SBR replaces the existing biological aerated flooded filter process at the adjacent Sandon Dock.

 Innovations on the project include a high-efficiency aeration system to reduce the power required to operate the works, reducing the carbon footprint of the wastewater treatment process. AECOM is currently on site working with the integrated GCA team. The works are scheduled for completion in 2015.

Commenting on the win, Nicola Henderson, AECOM’s head of proposals, design-build, Europe, said:

“As a flagship project, the new Liverpool Wastewater Treatment Works requires a robust and reliable solution, and the CASS process offers considerable advantages over other SBR processes. By using our own CASS technology, we are able to pass on a number of benefits to GCA and United Utilities. These include low capital costs, reduced operational costs and a process that is simple, flexible and robust.

“With over 180 CASS installations worldwide, including other large, multi-storey plants such as the world’s first BMA2 and BMA4 in Thailand, AECOM’s CASS design team will provide a wealth of experience to help ensure the successful delivery of this high-profile project.

“The high-quality treated water leaving the new CASS plant will be cleaner and greener, helping the continuing rejuvenation of the River Mersey.”

Mark Walker, principal project manager, United Utilities, explained:

“The new process at Liverpool is key to United Utilities ensuring that we continue to improve the water quality in the River Mersey. My team looked long and hard at the different processes available and I am confident that they have selected the best one for this application.”

As part of the detailed design process AECOM is providing extensive 3-D modelling. This will enable the scheme to be built virtually before any physical construction takes place. In conjunction with GCA’s own designers, the process enhances the design process so different disciplines have an accurate understanding of each other's physical building requirements, which eliminates costly errors traditionally rectified on site.

AECOM’s suppliers and manufacturers use the model to design their equipment to interface with other building elements and to avoid clashes during installation procedures. In-house engineers can identify and overcome design or safety issues more rapidly within a 3-D view, and make a difficult construction sequence simpler and safer.

Building Information Modelling (BIM) techniques will also be employed on the Liverpool project in order to enhance quantity information for ordering, costing and alternative material costs.