Welsh Water – Saltney and Kinmel

OCU, in conjunction with Welsh Water and Waterco, had the Saltney and Kinmel Bay Horizontal Directional Drill pipeline installations shortlisted for an honour at the Institute of Water Welsh Innovation Awards.

To cure blockages and bursts on existing sewerage rising mains, Dwr Cymru Welsh Water, (DCWW}, contracted out a scheme to undertake the replacement of the existing; the Saltney to Chester and Rhyl to Kinmel Bay WwTW rising mains in a single tender package. Each scheme included a major tidal watercourse crossing; the River Dee at Chester and the Afon Clwyd at Rhyl, where the original pipelines had originally been dredged into place at enormous environmental cost.

The Dee Crossing, as part of the overall 1.6 km scheme included a 264m long installation of 630mm diameter pipeline, and the Clwyd crossing as part of the overall 3.5 km scheme, included a 377m long installation of 710mm diameter pipeline.

Both crossings were extremely sensitive from an environmental and recreational perspective, with the Dee in particular having SSSI and SAC status. They are used extensively by walkers, cyclists, (National Cycle Route s68 along the Dee and NCR 84 along the Clwyd}, and boating groups.

It was imperative that the crossings were undertaken using a trenchless method to minimise the impact of suspended solids being introduced to the rivers, as the River Dee has cockle beds and a treatment works intake downstream of the site, and the beach at Rhyl has Blue Flag status.

Both rivers include extensive flood defences protecting vast areas of land.

Initially, Waterco Consultants were commissioned to produce System Assessments and Replacement Feasibility Study Reports. They took advice from OCU on the viability of using HDD during the production of the Feasibility Studies, following which Waterco were also tasked with the detailed designs for the replacement mains.

OCU won the tender process due to providing the most environmentally compliant and technically innovative solution to the mains replacement.