Ekki Bog Mat Access Road Replacement at Northmoor WTW

The brief

Affinity Water engaged us to replace the existing Ekki bog mat access road at Northmoor Water Treatment Works in Denham. Northmoor is an 18 million litres per day strategic treatment site, part of the infrastructure that supplies drinking water to customers across the north London and south Hertfordshire area. The existing bog mat access road had reached the end of its serviceable life. The job was to remove the old mats, prepare the subgrade, and lay a fresh run of Ekki hardwood in the same alignment so the site could continue to operate its vehicle movements safely.

Ekki is an exceptionally dense tropical hardwood used across the UK utilities sector for heavy-duty access roads. Where conventional road build-up isn’t practical, either because of soft ground, environmental constraints, or the need to remove the track later without permanent reinstatement, Ekki bog mats create a working surface that takes the weight of plant and heavy vehicles without the excavation and reinstatement a permanent road would require. On operational water treatment sites, they are a well-established solution for contractor access routes, plant lay-down areas, and temporary haul roads.

The challenge

Ekki is not a material you handle casually. Individual mats are dense enough to require specialist lifting equipment: a Hiab crane with a clamshell grab, rigged and operated by crew trained to lift, swing, and position mats at working height. The site context added its own constraints. Northmoor is a live strategic treatment works, with security perimeters, operational traffic, and the full set of controls that come with working inside a water utility’s secured asset.

Operating inside a working water utility estate also means the client’s own projects team is watching. Senior projects managers from Affinity observed the works throughout and fed back on how they were carried out.

Our approach

Joss, Tilly, Ryan, Emmanuel and Iulian carried out the works over two days in September 2025. The existing mats were lifted out with the Hiab, the subgrade assessed and prepared, and a fresh run of Ekki timber bog mats laid in sequence to form the new access road. Steel road plates and protective timber sheeting were used to support vehicle movement through the works, and traffic management was maintained throughout.

Outcome

New Ekki bog mat access road laid at Northmoor WTW, ready for continued operational and contractor traffic on site. Client feedback from Affinity’s own project management team on site throughout the works specifically called out the safety and efficiency of the way the job was delivered. That kind of feedback, from a client’s senior PM observing the works in real time, is the most useful kind.

For the broader service context see our groundworks work. The project sits under our work for water companies, extending beyond pipework and connection schemes into the estates civils that keep operational sites running.