Rossett flood risk and mitigation explained

Thursday, 23rd May 2024

As a responsible homebuilder, we take our commitment to the environment and sustainability seriously. When we’re considering the development potential of a site, including our Trevalyn Place development in Rossett, we explore a range of factors including the potential risk of flooding and enlist the help of experts during the planning process. We’re both obliged and committed to developing the site in such a way as it does not flood, either due to rainfall, nearby rivers or water features or for any other reason. Read on to find out more.


About Trevalyn Place


Located on Rossett Road, the site of our new homes in Rossett is allocated for housing in the Wrexham Local Development Plan and will help meet targets for new homes in the area.

Around 11 acres of the overall 15 acre site will be developed for housing, with mature landscaping around the boundary retained and pockets of public open space throughout the new neighbourhood.

Community investment agreed during the planning process includes local schools sharing circa £900,000, with the funding to be distributed via the local authority.


Site history and local area


The site was previously fields in agricultural use. Like many such fields, it was subject to the potential for water collecting on the surface following heavy rainfall. Images of the site taken some years ago, after a period of exceptionally bad weather, showed ponding in the fields. These pictures have been used out of context by some to suggest that the land is especially susceptible to flooding.

A large proportion of the village of Rossett sits in the natural flood plain of the River Alyn. Despite this, due to the development of the village and the surface water drainage network constructed through it, problems with flooding from the river are exceptionally rare, and limited to areas much closer to the river. Our development site lies on the edge of the village, around 200m from the river at its closest point, and on higher ground than the parts of the rest of the village that are closer to the river. Flooding of the site from the River Alyn would only come through a large proportion of the existing village, which illustrates just how unlikely this is.


Planning process


Under the Wrexham Council Local Development Plan, the site of our new homes in Rossett is considered entirely suitable for a housing development of the scale proposed and the land has been allocated for this purpose. Outline planning permission was granted for the scheme in February 2020 and reserved matters consent in February 2022. The final pre-commencement planning condition was discharged earlier this year, enabling work to start on site.


Expert assessment


During both planning applications, drainage experts at Wrexham County Borough Council, Welsh Water and National Resources Wales (NRW who advise on flooding and maintain flood mapping for the whole of the country) were consulted on the proposals. Extensive work was carried out, and a comprehensive Flood Risk Assessment was completed. A highly detailed flood model was produced to the latest Welsh Government standards and using NRW’s own data of the River Alyn. This flood modelling proved to the various experts involved that even in the most severe of weather events, and even allowing for a significant further 40% contingency to allow for the potential of climate change over time, there was no risk to the site of flooding post-development.


Sustainable drainage systems (SudS)


A detailed surface water drainage design for the site has also been approved by Wrexham Council. This is a SuDS design, developed in accordance with Welsh Government standards for sustainable urban drainage systems. It incorporates huge amounts of attenuation for surface water. When constructed this system will make the site extremely resilient to flooding from extreme weather, far more so than any older residential area.




We have given extensive consideration to potential flood risk and flood mitigation measures in relation to our development site in Rossett.

All this significant evidence collected, and work done, has demonstrated to the relevant public bodies that the undeveloped fields aren’t really any different from many other areas of agricultural land in that they’ve previously had the potential to become water-logged and hold standing water. When the site is complete and the surface water drainage system to be constructed is in place then our development won’t be at any risk of flooding.

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