Irk & Douglas UID’s

The River Irk UID project entailed the construction of a new reinforced concrete CSO (combined sewer overflow) chamber with associated electrically powered filter screens.

The buried chamber measured 5 m in width, 10 metres in length and 5 metres below ground. Following commissioning of the M&E works within the chamber, the existing CSO arrangements were decommissioned.

Upstream of the River Irk UID, over 250 linear metres of existing sewer needed to be upsized from 225mm diameter up to 450mm diameter at depths of up to 5 metres. The work was carried out ‘on line’ using open cut techniques and overpumping of existing flows.

The nearby River Douglas UID project was executed simultaneously with the River Irk UID. This entailed the construction of a smaller CSO chamber with associated static screen. Also, the re-construction of a new overflow sewer to the River Douglas, with associated new overflow structure. We also constructed new access roads and a compound area for future maintenance of the installation.

The majority of the works were undertaken on land owned by UU, with part of the new overflow sewer constructed through an area of ancient woodland. Rather than construct this section of sewer using traditional ‘open cut’ techniques, this section of sewer was installed utilising ‘no-dig’ sewer techniques. This was to minimise disruption caused to this sensitive area.

Bethell were employed on a ‘Design and Construct’ basis and developed the initial outline design that was originated by UU at tender stage.