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SOUTH DUBLIN COUNTY COUNCIL

MEETING OF RATHFARNHAM / TEMPLEOGUE / FIRHOUSE / BOHERNABREENA AREA COMMITTEE

Tuesday, April 14, 2026

QUESTION NO.2

QUESTION: Councillor R. Mannion

To ask the Manager what reviews are taking place to assess the impact of continued development on drainage and flood infrastructure downhill across Firhouse/Bohernabreena

REPLY:

Natural Water Planning Section assesses large housing and industrial developments at the planning stage so that they are designed to limit surface water flows to greenfield runoff rates or 2 litres per second, whichever is greater. This means that surface water from sites does not exceed pre development flows.

For brownfield development sites, surface water flows are attenuated at greenfield runoff rates, which greatly reduces surface water flows because usually there is no surface water attenuation on existing brownfield sites. 

As part of assessing surface water attenuation, flood management and surface water flow controls from sites, designers and applicants are directed to the following documents:

• The SDCC Sustainable Drainage Design and Evaluation Guide 2022.
• The SDCC Householder's Guide To Sustainable Drainage (SuDS). 
• The Strategic Flood Risk assessment in the County Development Plan 2022.
• The Planning System and Flood Risk Management, Guidelines for Planning Authorities November 2009 (OPW).

In assessing planning designs, SDCC promotes above ground, nature based attenuation instead of underground tanks.

Natural Water Operations carry out regular maintenance of the surface water network to alleviate blockages as required.

The Minor Works Programme addresses surface water network issues. 

There are 2 major Flood Alleviation schemes progressing in SDCC currently, the Poddle FAS and the Whitechurch Stream FAS.