Joint venture team uses BIM to improve co-ordination, buildability, operability and maintenance in the expansion of the Liverpool Wastewater Treatment works.
The £150M expansion of the Liverpool Wastewater Treatment Works will serve approximately 600,000 people when it is complete, with the capacity to take away 960M.l of sewage a day and treat it before it is released into the river Mersey.
A joint venture of Galliford Try Costain and Atkins (GCA JV) was set up to deliver detail design and construction services for the project for United Utilities Asset Management Programmes. Atkins was called upon to lead the implementation of a building information modelling (BIM) strategy rather than rely on traditional 2D workflows.
The new plant is located in an operational dock, which is subject to a preservation order by English Heritage. This meant that the design had to avoid damage to the walls. The dock gates had to be closed and a permanent closure constructed prior to dewatering, sand infilling, and piling.
According to Paul Heath, BIM lead adopter for Atkins water operations, BIM was introduced to be a time and cost saving asset. “On this project the footprint is very confined. The solution was to go up rather than out, so there are eight treatment cells over another eight treatment cells. We thought that designing in 3D could help us manage all that complexity.”
Starting with the main sequence batch reactor structure, the design team created a 3D model of the piles, base and wall starters, cutting 2D plans, and sections from the model using Autodesk and AutoCAD plant software. The 2D drawings were then sent to the Atkins global design centre for reinforcement detailing.
Atkins BIM specialist Matt Lees, says the design team overcame reluctance to use BIM. “We designed in 3D from the outset, and then generated 2D drawings from the models,” he says. “Those who were hesitant saw that you can easily create a 2D drawing from the 3D model if you need one.”
The team also used Autodesk Navisworks Manage software to create a federated model of the project for coordination and design review. The team then used this model to engage partners, suppliers, and the client’s operations personnel early in the design process.
“Using the model as a reference, operations staff from the client helped us understand how to optimise the plant for maintainability and safety,” says Lees. “When we’re done, the utility will have a virtual plant to which we can add equipment details to facilitate asset lifecycle management.”
The GCA design and construction team turned to this model again during construction planning. They linked the model to the construction schedule and created a 4D construction plan. Additional software enables the team to refer to this on tablet devices on site.
The Navisworks model was also used by the supply chain for pricing exercises. Rather than use 2D drawings, suppliers were encouraged to measure from discipline-specific models that showed design intent. This helped reduce the risk of measurement errors, contributing to improved accuracy and leaner pricing. The successful suppliers were contracted to supply their own detailed design models, which replaced the design intent models. “We coordinated and sequenced construction well in advance,” says Heath. “The 4D model let us rehearse the construction and helped us look for ways to reduce costs, improve safety, and work more efficiently.”
The success of BIM implementation was ably demonstrated by the recent completion of 386m of large diameter process pipework ranging from 1600mm to 2200mm pipes. The pipework was designed in the BIM model, fabricated off site, and installed between a number of fixed points with no on‑site cutting.
Lees says, “Working closely with the BIM design team, GCA Site Engineering carefully monitored each invert level, centreline, and pipe rotation. We were able to interrogate the model at any point during construction, giving our site supervisors the information they needed to replicate the 3D model.”