N65 Portumna Flood Investigation
A detailed flood investigation to identify potential sources of flood risk on the N65 at Carrigahorig, which also included the proposal of mitigation measures to limit disruption.
Following the closure of a section of the N65 for six weeks due to flooding, we were appointed by Tipperary County Council to investigate the cause and explore initial mitigation options.
- Client Tipperary County Council
- Location Carrigahorig, County Tipperary
Developing flood risk mitigation measures through in-depth analysis and hazard mapping
Following the six-week closure of the N65 due to flooding, we were appointed to conduct in-depth analysis to determine the potential sources of flood risk, examine existing flood outlines and develop appropriate flood risk mitigation and management measures.
To determine this we adopted a non-modelling approach - instead opting for statistical analysis of gauge data. Through this approach we were able to identify that Lough Derg was the primary source of flooding and that groundwater is close to the surface in the project area.
This analysis was also supported by mapping of the road hazards to identify vulnerable sections. As a result we were able to recommend a series of mitigation measures, which included suggesting that the road level be raised to suitable design standard and freeboard.
Alongside this recommendation, we also highlighted the benefit of installing additional high level culverts in order to manage residual risk. These recommendations were also supported by guidance on best practice pollution prevention measures.
