J Coffey Construction were awarded this design and build contract to improve the risk profile of the Iver Water Treatment Works by providing a second Contact Tank. The design intent was for the new and existing Contact Tanks to operate independently and the success of our contract allows the swapping of flow through one tank to the other without shutting down the works.

The installation includes pipework and valves to allow the entire forward flow to the contact tanks to be diverted back to the works inlet in the event that that a disinfection failure occurs.

The new reinforced concrete tank, which has three flow channels created by full height training walls and baffles, is 75 metres long, 16 metres wide and 6 metres deep and is fully submerged below ground.

A unique feature of the J Coffey design solution is the revolutionary design of the inlet flume in lieu of traditional baffles to achieve the ‘contact’ time of 30 minutes.

Throughout the project we were involved in detailed logistical planning to facilitate the integration of the new works into the existing without creating any unplanned ‘outages’ to this strategically critical facility

The majority of the works were undertaken by J Coffey direct operatives with the exception of the specialist 1600mm diameter pipelines, preparation and disinfection of the tank together with overall controls and commissioning