The company will construct a new detention tank at Bramhall Precinct car park to reduce the number of times the storm overflow operates into the brook, a tributary of the River Mersey. The shaft tank will intercept a sewer running into the existing Briarlands Combined Storm Overflow.
The contract has been awarded as part of the largest investment in wastewater infrastructure in the North West for a century. United Utilities is investing 拢13bn to protect and enhance over 500km of rivers, lakes and bathing waters whilst safeguarding drinking water supplies for millions of customers.
The site sits within an area with a high water table so Barhale and UU have collaborated closely to identify a suitable design solution. It includes diverting an 825mm diameter sewer running at 4m depth to allow construction of a 1,000 cubic metre shaft tank using a 12.5m diameter segmented caisson sunk to an invert depth of 13.3m.
Barhale will also carry out the MEICA fit out including new pumps in the shaft, control equipment kiosks, control panels, telemetry systems and incoming power supplies. A dual rising main will be connected to the network upstream of the CSO chamber.
Nick Curtis, regional director, northern, Barhale said: 鈥淭he project presents some significant technical challenges because of the location and site conditions and we are pleased to continue supporting United Utilities as part of their wide reaching AMP8 investment programme.
鈥淲e are already active across several aspects of the programme which are reinforcing the network鈥檚 ability to withstand storm events. They include constructing another smaller storm tank near this one in Cheadle and two more in Merseyside.
鈥淭he investment is aiming to reduce spill rates to fewer than one-in-ten-year events. The completion of the Briarlands CSO programme will be an important step towards meeting United Utilities鈥� target of reducing spills from storm overflows by 60% before 2030.鈥�
Work is scheduled to finish in summer 2027.