Broadway Underpass Recommendations Completed

Transport Minister, Conor Murphy, today updated the Assembly following completion of work recommended by the independent Investigation into the flooding of Broadway Underpass.

The Minister said: “The results of the hydraulic model clearly show that the major cause of the flooding was a partially blocked screen at the Clowney Water inlet, in addition a section of embankment on the eastern side of the Clowney Water was breached and washed away during the flooding event. It is evident that the river drainage system provided is compliant with the requirements of the contract.

“Measures have been implemented upstream of Broadway to intercept debris in the upper reaches of the Clowney Water before it reaches the Broadway System. Modifications have also been made to the Clowney Water inlet screen to make it more efficient and easier to clean. The contractor has also raised the banks of the Clowney Water immediately upstream of the Broadway Culvert to provide additional flood protection and enhance the efficiency of the system. All of these additional works have now been completed.

“It is therefore clear that if the flows of 16 August 2008 were to reoccur, with these new measures in place to ensure the screen remained clear, similar flooding should not occur.”

The Minister announced that the following three main recommendations in the independent report have been completed;

• raising the banks of the Clowney Water;
• implementing enhanced procedures to ensure public safety; and
• assessing the hydraulic efficiency of the drainage system using a physical model of the system.

Rivers Agency has recently reassumed responsibility from the contractor for the Clowney / Blackstaff drainage system including the early warning system at the Clowney inlet.

Procedures have been established for notification of relevant authorities and attendance by the relevant people in the event that an alarm is triggered.

The Minister said: “I am advised that Rivers Agency in partnership with all responsible authorities as required by the Floods Directive is currently carrying out a Flood Risk Study for Belfast.

“The information obtained from the modelling work will be used to inform the study and help to identify proposals to better assess and manage the overall risk of flooding.”

Notes to editors:

1. The main recommendations of the independent report and the Roads Service comments are outlined below:

• Recommendation 1 - Completion of the works to raise the banks of the Clowney Water immediately upstream of the culvert to a level 500mm above the 1 in 100 year designed flood level.
• This initial work was completed in 2008. The modelling work confirmed that an enhanced level of protection could be provided with a marginal increase in the levels of the banks of the Clowney Water. These works have now been completed and will provide additional capacity in the system.
• Recommendation 2 - Development of enhanced procedures to include more regular inspection on the Clowney Water and introduction of an early warning system to advise of impending high water levels to ensure the safety of the public until completion of the works.
• The DBFO Co implemented enhanced procedures which relate to MET Office forecasts and installed a telemetry warning system. There was an escalating level of response associated with the severity of the MET Office warnings / warnings from the telemetry system. Since handover, Rivers Agency has developed its own procedures.
• Recommendation 3 - Carry out an assessment of the hydraulic efficiency of the drainage system. The hydraulic modelling has been completed. The results from the assessment of the hydraulic efficiency of the Clowney / Blackstaff drainage system have increased Rivers Agency’s understanding of the flow regime and dynamics of the drainage system.

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