In the past month storms have caused dreadful flooding around Ireland, from Cork to Newry, writes Michael O’Donohoe, country director, Wavin Ireland.

And so it continues. Met Éireann recently published a report on Ireland’s climate averages for 1991-2020 which revealed an increase in rainfall of about 7% over the last 30 years with annual average rainfall for Ireland at 1,288mm over that period.

Michael O’Donohoe, country director, Wavin Ireland.

Urban centres and parched greenfield sites simply can’t absorb the extreme rainfall events. Because water can’t soak directly into the soil, surface water run-off is increasing – overwhelming drainage networks and causing water bodies like rivers and lakes to overflow, resulting in flooding.

But there are ways to mitigate the effects of extreme rainfall and protect homes, businesses and people from flooding. One of the key ways to achieve this is through a commitment to Sustainable Urban Drainage Systems (SuDS). 

Manage rainfall

SuDS help a developed site to manage rainfall and surface water as well as – and potentially better than – it would have done as a greenfield site. By managing surface water run-off as close to source and surface as possible, SuDS mimic natural drainage and help water to naturally soak into the ground, to evaporate from surface water and to provide transpiration from vegetation, mitigating flooding, reducing pollution, and providing green spaces and creating amenity for the community,

There are a wide range of SuDS components  available; including green roofs, rain gardens, tree pits, permeable paving, swales, perforated pipes, rainwater harvesting, soakaways and various types of underground attenuation and storage tanks.

Successful SuDS schemes typically prioritise early stakeholder engagement and careful planning in order to create effective and cost-efficient solutions.

Engineers, landscape architects, urban designers, local authorities, water companies and developers all have a role to play in developing SuDS schemes, with the best designs incorporating the four pillars of SuDS. They are: managing water quantity; managing water quality; creating amenity and creating a habitat for biodiversity.

With their strong contribution to place making in urban areas, and ability to mitigate increasing flood risk, SuDS are seemingly an obvious choice for developers. However, although SuDS technology has been available for decades, it is yet to become ubiquitous on new developments in Ireland.

SuDS are increasingly required by local authorities across new developments, redevelopment and retrofit projects. 

In the Cork County Development Plan 2022 an advice note on Surface Water Management says that "every application for development must submit a Drainage Impact Assessment (DIA) demonstrating how the development successfully uses Sustainable Urban Drainage Systems (SuDS) and nature based solutions to manage surface water within and adjacent to the site”.  

Greater Dublin Strategic Drainage Study

Dún Laoghaire Rathdown County Council is also actively recommending the implementation of SuDs as part of new developments and redevelopments while the Dublin City Council Development Plan (2022-2028) has identified SuDS as preferred, firming up the city’s 2005 commitment to mandatory SuDS on new developments in the Greater Dublin Strategic Drainage Study.  

Around the country, councils like Wicklow County Council are following suit, and have made a firm commitment to SuDS. In its latest development plan, the council stated that it “requires all new developments to adopt the SuDs approach”. But while there’s clear progress in some regions, others, continue to exercise less stringent requirements for city development plans.

While SuDS have achieved significant uptake in parts of Ireland, it’s vital to keep this momentum going. Ideally, all water management stakeholders will come together to strengthen regulations and deliver a coordinated, effective strategy for surface water.

SuDS need to become a mainstream part of surface water management – a compulsory stage in developments and a key consideration in schemes to regenerate or improve existing urban environments. 

Launching in 2024 Wavin AquaCell NG is the latest generation of AquaCell, attenuation/soakaway units to manage Stormwater. With its nested design, units
require 1/4 of the space on site, with four times fewer deliveries and four times lower CO².

For more information on Wavin Geocellular modular units for attenuation and infiltration see: https://www.wavin.com/en-ie/solutions/aquacell or  Contact projects.ie@wavin.com