An innovative sustainable urban drainage system from Aggregate Industries has helped Wirral Borough Council to minimise the impact of a new 6,000 square metre car park.


The new ‘park and ride’ is part of a £1.26 million package of measures to help Wirral capitalise on the influx of visitors expected during the Royal Open Golf Championship at the Royal Liverpool Golf Club in Hoylake, including a raft of transport improvements.

Infilta block paving

Following the identification of potential flooding issues as a result of the development, Wirral Borough Council engineers took the decision to implement an innovative Sustainable Urban Drainage System (SuDS), the first time this technique has been used for a scheme of this scale within the Merseyside area.

Traditional drainage practice moves rainwater as rapidly as possible from the point at which it has fallen to a discharge point – the local drainage network. However, in this particular area, investigations showed that it could increase a risk of flooding in the local area after medium rainfall.

Wirral Borough Council therefore enlisted Aggregate Industries' specialist expertise to help design a system to minimise this risk.

Following detailed investigations, Aggregate Industries and Wirral Council jointly designed a solution specific to the requirements of the site. Due to the relatively good permeability of the soil and restrictions on discharging water into the existing drainage system, they developed a system which would replicate the natural infiltration of surface water into the water course.

This required the level of the car park to be elevated to increase the capacity for controlled drainage, using Aggregate Industries’ open granular sub-base to delay the speed with which rainwater enters the watercourse.

The Infilta Block Paving was then selected to surface the parking areas. With a specially designed nib structure providing a 5mm space between adjacent blocks, Infilta Block Paving allows ingress of water through to the storage system. Available in Red, Brindle, Charcoal and Natural Grey, the blocks combine the aesthetic appearance, strength and performance of Aggregate Industries' Charcon range established block paving with the added environmental benefits of sustainable drainage.

In addition to reducing flooding risk, our solution has delivered additional benefits including minimal visual impact, reduced pollution and waste water, improved biological diversity and consistent soil moisture levels.

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