IN Brief:
- Kier’s £8.7m early contractor involvement phase supports a Maple Lodge upgrade with an initial target cost above £265m.
- The programme combines major civil, process, storm storage, tertiary treatment, electrical, control, and monitoring works at an operational sewage treatment site.
- Early design and construction planning will determine how new treatment capacity is introduced without interrupting existing wastewater operations.
Kier has begun an £8.7m early contractor involvement phase at Thames Water’s Maple Lodge Sewage Treatment Works in Hertfordshire, shaping a wider upgrade with an initial target cost of more than £265m.
The contractor is already on site with Thames Water, designers, and supply chain partners, developing the design and construction sequence around a treatment works that must remain operational throughout the programme. Kier describes the scheme as its largest wastewater project to date.
The proposed scope spans storm storage, inlet works, screening, primary settlement, biological treatment, new final settlement tanks, tertiary treatment, and improvements to electrical, control, and monitoring systems. Thames Water is also planning greater storm tank capacity and improved effluent quality, including a target to reduce phosphorus entering the receiving river to below an average of 0.25mg/l.
That mix of civil, process, mechanical, electrical, instrumentation, control, and automation work makes the ECI phase particularly important. New structures cannot be designed in isolation from existing treatment processes, and temporary arrangements, isolations, access, commissioning, and process changeovers have to be coordinated before the main works are fixed.
Andy Lingham, managing director for water at Kier, said early involvement would allow the team to “develop the design, manage risk and plan delivery around a live operational site”. The constraint is fundamental to the job: Maple Lodge cannot simply be taken offline while new assets are built and connected.
Treatment capacity has to be maintained while individual systems are modified, bypassed, replaced, or commissioned. A design that appears efficient on paper can create significant programme risk if it requires excessive shutdowns, leaves insufficient temporary capacity, or creates conflicts between process equipment and civil works.
The programme therefore places considerable weight on sequencing. Structural work around tanks and channels has to align with installation of process equipment, cable routes, controls, access platforms, and monitoring systems, while commissioning plans need to account for how new and existing assets will operate together during transition.
Earlier specialist engagement can also expose buildability problems before they become site changes. Process suppliers, electrical contractors, control system specialists, and civil subcontractors all influence interfaces that may be difficult or expensive to alter once concrete is poured or equipment has been ordered.
Kier’s relationship with Thames Water extends across several asset management periods. Projects cited by the contractor include the Deephams Sewage Treatment Works upgrade, a £66m upgrade at Mogden, and the £45m Faringdon-to-Blunsdon pipeline. Kier also held positions on Thames Water’s AMP7 Capital Programmes Framework and is supporting AMP8 work including early contractor involvement at Harpenden.
The scale of AMP8 is increasing competition for the same design, delivery, and specialist resources across the water sector. Large wastewater schemes need civil engineering capacity, process knowledge, electrical and controls capability, commissioning expertise, and long-term supply relationships, often at the same time as utilities are trying to accelerate work across multiple sites.
A contractor able to coordinate those disciplines under one programme can reduce the number of handoffs between packages, although it also carries greater responsibility for design integration. Interface risk does not disappear simply because work is brought together under a larger contract; it becomes part of the main delivery team’s planning burden.
At Maple Lodge, the £8.7m ECI phase gives the project team time to resolve those issues before the bulk of expenditure is committed. Cost planning, design maturity, temporary works, procurement sequencing, and commissioning strategy can be tested against the reality of a live operational site rather than left to the opening months of main construction.
The same period should also help identify where long-lead process and electrical equipment needs early procurement. Water projects can be vulnerable to delays in specialist equipment, particularly where bespoke process systems, switchgear, controls, or instrumentation have to be manufactured, tested, and integrated with existing assets.
There is little room for casual substitution later. A replacement product or system may affect power demand, controls, maintenance access, process performance, structural loading, or commissioning, so design decisions taken during ECI can influence both procurement flexibility and the amount of change tolerated once work begins.
Maple Lodge is entering the point at which programme risk is being converted into specific design and delivery decisions. The main construction package has not yet been fixed, but the project’s size means relatively small errors in sequencing, temporary arrangements, or package interfaces could have material effects on cost and completion.
The £265m-plus target also provides an early test of the water sector’s preference for contractor involvement before complex AMP8 designs are fully fixed. If the ECI phase resolves operational and technical constraints before full construction starts, its value will be measured in the changes, shutdowns, and delays avoided later.
