COMHAIRLE CONTAE ÁTHA CLIATH THEAS
SOUTH DUBLIN COUNTY COUNCIL

MEETING OF RATHFARNHAM AREA COMMITTEE

Tuesday, December 15, 2009

QUESTION NO. 4

QUESTION: Councillor E. Coburn

"To ask the Manger for an update on the Flood protection measures that are in place for all rivers in the Rathfarnham area and  what liason takes place with surrounding councils that said rivers are sourced from before reaching the Rathfarnham area?"

REPLY:

In late 2005/early 2006 the three local authorities in whose functional areas the river Dodder flows i.e. South Dublin County Council (SDCC), Dun Laoghaire Rathdown County Council(DLRCC) and Dublin City Council(DCC) agreed that a study of the river would be commissioned in order to provide a comprehensive report on the Flood Risk Assessment and Management of the river. The Office of Public Works (OPW) is funding the study as it forms part of the national Catchment Flood Risk Assessment and Management Studies (CFRAMS). Dublin City Council is the Contracting Authority on behalf of the three local authorities.  Following the public tendering procedure in early 2006 Dublin City Council appointed consultants/service providers, R.P.S., to carry out the Risk Assessment and Management Report. The major stakeholders, DCC, OPW, SDCC, DLRCC and RPS meet at Steering Group level every three months to review the progress of the contract.  The final plan will require the agreement of all three Councils and the OPW.

The core purpose of this study was to assess the spatial extent and degree of flood hazard and risk within the Dodder catchment, to examine future pressures that could impact on that risk, and to develop a long-term strategy for managing the risk that is economically, socially and environmentally sustainable.

The Report will include measures for the development of a robust model representing the hydrological and hydraulic characteristics of the River Dodder catchment, such a model will provide for the mapping of the flood risk.  Using model output the technical and economic merit of various options for flood management, taking account of current and future land developments, will be presented within the report.

To achieve this aim the following study objectives have been identified:

• Review of land usage and planning requirements
• Capture and analysis of all data including existing models
• Surveying the catchment and river estuary
• Hydrological analysis
• Hydraulic analysis including development of a hydraulic model
• Environmental assessment
• Risk assessment
• Development of flood risk management options
• Preparation of a catchment flood risk management plan including a river maintenance programme
• Provide deliverables which meet the above aims and goals
• Effective management of the study

The main tributaries of the Dodder River are included in the above Risk Assessment and Management Report viz. the Whitechurch, Owendoher and the Tallaght streams.

In June 2008, the consultants issued a Strategic Environmental Assessment (SEA) scoping report on the River Dodder Catchment Flood Risk Management Plan.  This Report is available to download on the Dublin City Council website: www.dublincity.ie/waterwasteenvironment/pages/riverdoddercatchmentfloodriskassessmentmanagementstudy.aspx  Comments can be sent to the above website or doddersea@rpsgroup.com

The final SEA statement will:

• Outline the option or combination of options selected for taking into the statutory planning process;
• Outline the reasons for selection;
• Outline how environmental considerations have been taken into account in the selection process; and
• Outline monitoring measures to be implemented

Further plans for the Dodder River Risk Assessment and Management Strategy include a public information days on the flood risk management, a draft CFRAMS and Environmental Report consultation and a final Strategic Environmental Assessment (SEA) statement.

R.P.S., were also asked to produce an interim modelling report on the Whitechurch River, a tributary of the Dodder, as a result of serious flooding experienced  in the catchment on 22 June 2007. The  Whitechurch River Interim Modelling Report issued from R.P.S. in July, 2008 with recommendations on reducing the flood risks along the Whitechurch River. Following the publication of the report, South Dublin County Council in conjunction with Whitechurch National School completed an emergency culvert upgrade on the Whitechurch Stream at the entrance to the school to prevent further flooding and property damage in the area. The cost of these works was approx. €150,000.

Minor ongoing flood relief maintenance work is funded through the Drainage Maintenance Budget. The drainage maintenance section has carried out significant surfacewater drainage system maintenance work and recent works include clearing of the piped Ballycullen Stream through Castlefield and Glenvara, provision of flood alleviation works on the Poddle at Tymon and at Cappagh, and provision of an overflow pipe on the Robinhood Stream.

The Whitehall Road works were completed in early 2009 and funded jointly between the Roads Department and the Drainage Department through levies