Water Quality First for Cardiff ‘Super School’

An innovative new water treatment technology has helped a prestigious ‘super school’ development in Cardiff to achieve a gold standard in environmental protection, needed to care for the historic and sensitive natural landscape on its doorstep.

The multi-functional drainage solution designed by engineers at Cambria Consulting overcame significant challenges to successfully manage both the quality and quantity of surface water runoff and led to the first UK installation of an SDS Aqua-Filter™ filtration system.

The 6.5ha Eastern High School campus in Rumney neighbours a Site of Special Scientific Interest (SSSI) that forms part of the Gwent Levels, a protected area flanking the Severn Estuary between Cardiff and Newport and drained by a network of reens.

The Challenges
Ed Hoskins, Senior Associate with Cambria Consulting Ltd, explains: “Redevelopment of the campus within the existing footprint left no space to incorporate any above-ground attenuation or vegetative treatment. The site had shallow falls and lay partly within a designated flood plain. There was 2.3ha of impermeable area together with a groundwater table that provided little opportunity for any infiltration.

“Any discharge from the site needed to be directed through an existing outfall into the highly-sensitive Pil du Reen watercourse, which flows into Caldicott and Wentloog Levels, and eventually into the Severn Channel.”

Sensitive Environment
The drainage solution required by Natural Resources Wales needed to demonstrate robust ‘belt and braces’ protection. In this area of flats and wetlands, and within a functional flood plain, only the lowest possible discharge flow rate was permissible to avoid any potential for disrupting the sensitive ecological balance.

Ensuring the runoff was free from sediment and any attached hydrocarbons was essential as the Gwent Levels are rich in plant and aquatic life, as well as mammals including otters and water voles and a variety of water birds. The Rumney and Peterstone SSSI itself supports important and rare aquatic plant species and invertebrates.

Treatment
An SDS Aqua-Swirl™ hydrodynamic vortex separator upstream of an SDS Aqua-Filter™ filtration unit were integral to the solution. On the upper portion of the site, runoff from a 79-space car park, delivery service yard and an area designated for the teaching of practical construction skills is treated by the two devices. Water passes first through the Aqua-Swirl™ to capture gross pollutants and hydrocarbons, before being polished by the Aqua-Filter™ to remove finer silts and dissolved pollutants, using filtration media selected by SDS to meet the specific needs of the site.

Attenuation
To ensure attenuation and avoid the potential for flooding up to a 1 in 100-year flood event + 30% allowance for climate change, an SDS GEOlight® stormwater attenuation system underneath the school’s sports pitches is capable of storing up to 1,950m³ of treated water.

Cambria Consulting identified an existing outfall within the site boundary that facilitated connection to a drainage pipe that discharged into the Pil Du Reen. Discharge from the two GEOlight® tanks is regulated by vortex flow controls, with the final discharge from the site restricted to a maximum flow rate of 5 l/s.

About SDS
SDS designs, manufactures and installs water management systems for sustainable infrastructure. The company is the UK’s leader in Sustainable Drainage Systems and has a broad product portfolio that includes solutions for the surface water, wastewater and industrial cooling water industries.

Every SDS solution is intelligently engineered to protect the water environment effectively and efficiently and to help customers, both in the UK and around the world, to control, treat, store and distribute water. SDS systems are used in all kinds of infrastructure projects from residential and commercial developments to highways and transportation.

Established in 2002, SDS is a privately-owned company with headquarters in Biddisham, Somerset. SDS has recently invested over £2 million in extending and modernising its design, engineering and manufacturing facilities in nearby Highbridge. The new operation has enabled the company to create the industry’s first closed loop manufacturing facility for post-consumer PVC waste to be fabricated into finished goods and accounts for 50% of the company’s manufacturing output.

In 2017, SDS was named Small to Medium Sized Business of the year in both The Lloyds Bank National Business Awards, and in the UK Business Awards (+10 years category).

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