Articles & Case Studies

Hydrok resolve an unusual CSO problem for United Utilities

Posted: Thursday 10th November 2011

Hydrok UK Ltd were asked by United Utilities to offer a solution for the refurbishment of their Combined Sewer Overflow system located in the Church catchment of Accrington in the Hyndburn drainage area of East Lancashire. The unusual factor in the project was that due to a fairly steep topography in an area of approximately 1,700 hectares, serving a total residential population of around 85,000, the CSO chamber is located 18 metres below ground within an 84m long tunnel.

Access to the CSO chamber through the existing entry point was restricted due to Health and Safety issues, therefore, a solution to resolve access issues whilst installing the new CSO system became the order of the day for the Hydrok Design and Engineering team.

The Hydrok plan was to install 10 MecMex 3m/180 degree hydraulic screens to meet the sewer flow demand within the first 25m of the tunnel. This meant that to comply with Health and Safety issues a new 4m diameter shaft needed to be sunk down to tunnel level. Through the new shaft, the MecMex screens and equipment could be lowered and it could also be used as a secondary emergency escape route via powered winches for personnel.

Specifically designed bespoke equipment was designed to allow for the 10 MecMex screens and associated steelwork, in excess of 20 tonnes worth, to be correctly installed in the designated location.

A bespoke hydraulic management system was designed to control the hydraulic operation of the MecMex screens, with controls located at ground level thus reducing the need to enter the chamber for operational control and general maintenance. Hydrok engineers both designed and installed the complex hydraulic solution using an ingenious array of hydraulic pipe work to comply with all Health and Safety requirements.

The completed refurbishment was commissioned into full operation on 7th July 2011.

Martin Tolman, Hydrok’s Technical Sales Manager said “This was a challenging project for all involved. The location made it necessary to construct a temporary bridge over the local canal to enable access for construction and delivery vehicles etc and to excavate a second 20m access shaft to the CSO chamber below. The Hydrok screening solution enabled United Utilities to utilise the existing chamber and for the screening facility to be assembled in sections capable of passing through and down the 20m access shaft. We were delighted to complete the project without any problems and within the programme. My thanks to all involved.”

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