Challenge

ELIQUO HYDROK 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 system extends over approximately 1,700 hectares and serves a total residential population of around 85,000. The area has a fairly steep topography and 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. A solution to resolve access issues whilst installing the new CSO system became the task for the ELIQUO HYDROK Design and Engineering team.

Solution

ELIQUO HYDROK worked closely with United Utilities consulting partners for a period of 3 years to develop an engineering solution to this unique problem. UU and their consultants decided that ELIQUO HYDROK should undertake the full engineering specification, method and completion of installation, as well as the commissioning and handover. This ensured that all design FEA, CDM and RAMS conformed to ELIQUO HYDROK’s quality control specifications thus providing the end client with a robust fully operational and fit for purpose solution.

A temporary bridge was constructed over the local canal to enable access for construction and delivery vehicles, and to excavate a second 20m access shaft to the CSO chamber below. The 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.

The ELIQUO HYDROK proposal was to install ten MecMex 3m/180 degree hydraulic screens within the first 25m of the tunnel to meet the sewer flow demand. 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. Bespoke equipment was manufactured 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. ELIQUO HYDROK engineers both designed and installed the complex solution using an ingenious array of hydraulic pipework to comply with all Health and Safety requirements.

Outcome

The complete installation was carried out by Hydrok engineers and in-house fitting team without the use of sub-contract labour. The commissioning was also carried out with reference to all of Hydrok’s requirements, including internal QA system of check sheets.

The equipment was finally handed over to the client following the completion of the commissioning checks, the issue of full Operation and Maintenance manuals and the delivery of operator training. The complete installation was covered by Hydrok’s warranty and aftersales service.