Flood Risk Assessment, Woolston, Warrington, NW England
Dec 6, 2017

RAB Consultants completed a Flood Risk Assessment and sequential test to support an industrial development at a site adjacent to the River Mersey at Woolston, near Warrington in NW England.

The development site is located in Flood Zones 2 and 3 in accordance with the Environment Agency’s Flood Map for Planning and is benefitting from defenses. The development is for the conversion of a brownfield piece of land to a concrete works on land at an industrial estate.

A recently constructed sheet pile flood defense wall was identified to be providing the benefit to the site. The RAB staff undertaking the site visit are T98 accredited visual flood asset inspectors and carried out a visual condition survey of the defenses whilst on site to better inform the risk assessment.

RAB Consultants carried out a GPS topographic survey during a site visit to inform post construction ground levels. These were used to inform the overall risk from a breach or overtopping of the defence and inform suitable mitigation options to help reduce flood risk to the site.

An additional consideration was given to the risk from surface water flooding, due to the entirely impermeable nature of the site. Due to the nature of concrete production the site, developers identified that although SuDS were not included in the development proposal all surface water would be harvested and used in the industrial process.

It was suggested that resistance and resilience measures could be considered for any future renovation works to safeguard the site office against surface water pooling and that operators sign up to the local flood warning.

It was concluded that the development is appropriate given the flood risk, and will not increase flood risk elsewhere.