Thames Water has gone out to tender with a major contract for an upgrade to its Maple Lodge Sewage Works with an estimated total value of up to £270 million.

Photo credit © Mark Percy (cc-by-sa/2.0): Maple Lodge STW

The water company is looking to significantly increase the capacity of the sewage treatment works and storm tanks, as well as provide quality improvements to the final effluent (Ammonia and Phosphrous).

The project includes the following packages of work:

An additional inlet screen with civils alterations and screening handling upgrade

• An additional detritor and flow inlet channel, incorporating a new storm separation weir
• A new storm tank and river outfall, including flow transfer culvert and new storm return pumping station
• Upgrades to the existing six PSTs and conversion of three storm tanks into PSTs, fitted with chain and flight scraper
• Replacement Primary chemical dosing pumps to aid Phosphorus removal
• A new activated sludge plant Bank C, with new feed PS and blowers
• Eight new 28m diameter final settlement tanks, interconnecting pipework, distribution chambers and RAS system
• A new secondary chemical dosing system to aid Phosphorus removal
• Two new Tertiary Solids Removal treatment plants, one serving the effluent from Bank A and B, and one serving the effluent from the new Bank C
• An additional Drum thickener
• New incoming switchboard for the new DNO supply
• Modification and upgrade of HV/LV networks
• Modification and upgrade to the power management system and site-wide SCADA
• Modification and upgrade to the Process SCADA
• Additional standby powered generation
• Demolition and removal of redundant structures, plant and equipment

The potential contract value is currently estimated at between around £140 million to £280 million, with an estimated contract start date of 20 October 2025 and an end date of 29 March 2030.

Deadline to submit inquiries about the tender is 5:00pm on 25 April 2025, and the deadline to submit requests to participate is 10:00am on 6 May 2025.

Interested suppliers are invited to register their interest in participating by completing an online form to provide their company name and contact details of two people from the organisation with whom Thames Water can correspond.

Following registration suppliers will then be issued with access to the project documentation. Thames Water’s Procurement Support Centre will be managing the submission process.

Once a supplier has completed, and submitted, their details Thames Water will then send the nominated representatives an invitation to access its Project SharePoint site, the PSQ and related documents necessary to complete their initial submission and an exclusive document library to upload responses accordingly.

Suppliers who successfully pass the PSQ stage, will then be provided with additional system access for the next stage of the procurement process.

Click here to access the online registration form.

Click here to access the tender documentation online.