Dee-crossing Connah's Key
Project Location:
Connah’s Key
Client Name:
Dŵr Cymru Welsh Water
Project Description:
OCU was awarded the Dee Crossing contract, located in Connah’s Quay. Our teams designed and installed two 860m-long barrier pipelines under the River Dee using Horizontal Directional Drilling (HDD).
We completed enabling works for the project, including site compounds at Connah’s Quay and within Tata Steel.
OCU installed cross connections on the Alwen main and Brenig main, allowing future connection points for the pipework. We carried out flushing and cleaning of the existing main. This was followed by HDD and open cut civils works to connect two water mains.
Key Stats:
355mm PE SDR11, HDD 355mm OD X 2 - 860M in length
Under pressure CCTV on mains
Mobilisation of 100-ton HDD rig + ancillary equipment
Pressure testing the main up to 21 bar
Managing all site ecology with considerable constraints
52 Weeks
Duration
Challenge
Drilling under the River Dee with the risk of unknown ground condition
Location of works, located in a steel mill live site
Enabling works in built up heavily populated urban areas
Complex connection on CI mains with cleaning and flushing
Flushing water from the main HDD filter tanks and then into River Dee
Undertaking under pressure connections to allow new valves to be installed without affecting the network
Solution
SDR9 pipe was used to ensure no damage to pipe integrity during installation
Boreholes and GI designs completed by OCU and unknown information estimated utilising formation data
OCU Trenchless engineers tracked and steered drill to within +/- 100mm tolerances
Under pressure connection undertaken to allow other connection to be undertaken with no loss of service to DCWW customers
Pipe tested above ground prior to installation, as well as once in place
Outcome
Project fully completed with a satisfied client – was reallocated to OCU after 3 years and no solution from a former supplier
All final connections made and all enabling works completed
Close collaboration between OCU and DCWW throughout the project
OCU worked with all stakeholders and local authorities
All additional scope works completed as required in given timeframes to exceptional standards
