Relocating Guildford sewage treatment works

We've agreed to relocate our Guildford sewage treatment works (STW). This is so the development of the new Weyside Urban Village can take place. The move is in agreement with the Guildford Borough Local Plan.

The project will include 1,500 new homes and new community facilities. It will also help improve the local area with 6,500m² of commercial space.

Guildford Borough Council is funding the relocation project. We’re working closely together to ensure a smooth overlap on both our projects. Our remediation strategy has been approved by the planning authority and stakeholders.

Construction update (Summer 2025)

Construction has been going well since starting this project. Work we've done so far includes:

Over 800,000 hours of work completed
14,000m3 of concrete poured
Major precast concrete structures completed
3,500 pre-cast piles and 7,500 inclusion piles installed
1.4Km tunnel drive and shafts completed
Outfall pipes and headwall at the River Wey completed
New administration building work started
Underground infrastructure (pipework and ducting) work started
Installation of mechanical equipment started
Above ground pipework installation started

Our focus now is completing the mechanical equipment installation. We're also planning the electrical installation programme. This will make sure we're ready to start commissioning the new plant in 2026.

We expect the works to be fully complete and operational in Spring 2027.

Innovative methodology to compact the site and prevent long term settlement

Driving pre-cast concrete piles into the ground to provide stable foundations for the structures

Tunnel boring machine (named Daphne by a local school) at its end point after covering 1,400m

Regular structures are manufactured in factories and then assembled on site. Complex structures are expertly built on site using formwork, steel reinforcement and concrete

Whilst verifying the integrity of our new structures, test water is recycled on site. This reduces demand on precious resources and cuts down our carbon footprint.

Polymer kiosks hold chemicals which are used for treating sludge which is later converted into energy

Benefits of the project

Capacity for treatment of wastewater will be increased for a population of at least 120,000
The site will have space for future expansion. This will be in line with modelled growth and the impact of climate change
Our proposal will result in 10% net gain in biodiversity value
Minimising the long-term visual impacts of the site. We'll do this by improving and supplementing the north trees which screen the site

How we're working to reduce impact

We’re using the latest odour control methods to minimise any impacts on our neighbours
Our new discharge location will not impact the flooding potential in the River Wey. We’re providing increased storm capacity
Work will not impact the nearby allotments. Mitigation will be in place to reduce the impact of noise or light during construction
There will be no increase in traffic once the site is operational. Construction traffic will avoid peak hours where possible

How we'll build our new STW

Our relocation project has three key elements and will be done in four phases:

Phase 1: Ground improvement

This work was completed in February 2025.

We've successfully finished this phase having stabilised the ground and installed over 10,000 piles.

Phase 2: Civil engineering

This work is due to complete late in 2025.

Major structures are complete. Deliveries of concrete (pre cast or in concrete wagons) will dramatically reduce now. We will still be delivering some materials to site whilst this phase is being completed.

We have used pre-cast concrete panels for quite a few of the structures. They were built off-site and then assembled on-site later. This was a quicker method, safer, involved fewer deliveries, and created less noise as a result.

Phase 3: Mechanical and electrical engineering

From Autumn 2024 to Summer 2026.

We have been receiving and installing various mechanical and electrical equipment. This has started to be installed on site.

During this phase, there will be minimal disturbance to our neighbours.

Phase 4: Commissioning

Winter 2025 to Spring 2027.

The new STW will start to become operational and the existing STW will be taken out of service. During this phase, there'll be minimal disturbance to our neighbours.

Get in touch

If you have any questions or concerns, please get in touch. Call us on 0800 316 9800 selecting option 1 and quoting BB00425695.

For business customers, please contact your retailer for additional information.