In late 2017, the Welsh Government committed to constructing a new facility at Offa’s Dyke Business Park, Welshpool, to support the growth of Invertek Drives, a local manufacturer of electro-mechanical variable frequency drives. ACO Water Management’s StormBrixx attenuation and infiltration stormwater management system was specified at the 5500m2 facility.
Keeping the new facility and surrounding area free from excess surface water, as well as future-proofing it from the effects of extreme flash-flooding and increased rainfall due to climate change, was an essential element of the structural engineering work on site.
The new facility would result in a significant reduction in the business park’s natural infiltration ability, so the proposed solution needed to not only meet the required infiltration levels of planning, but be flexible enough to fit into the limited available footprint around both pre-existing and planned infrastructure.
Crucially, any significant rainfall could not impact the existing infrastructure or adjoining watercourses.
ACO’s StormBrixx system was selected as the solution to the project's challenges.
A total of six soakaways were required for the project and were installed in two phases: the first in late 2017 during the principal construction on the new facility; and the second in early 2018, once the bulk of the structural building work had been completed.
The flexibility of the StormBrixx system allowed a variety of configurations to be factored into the design, including a number of 'P' shaped soakaways. This enabled a crate-free zone to be included in the eye of the 'P', leading to a greater surface area in contact with the soil to maximise infiltration rates.
The water management process
Surface water run-off from the hardstanding areas is collected and conveyed via channel drainage in the service yard and car parking areas. Given the high load demands of the service area, 30m of ACO S100 channel drainage was used.
S100 is a system specifically designed for heavy-duty applications, and is accredited to Load Class F900 – meaning it can withstand vertical loads of up to 900kN.
The channels were installed with sumps to retain grit and debris as the water is conveyed into a Class One bypass interceptor which removes any oil or petrol from those areas. It then enters the ACO StormBrixx HD soakaways, where it is joined by water from the building’s roof, which drains directly into them.