Overview

SDS was appointed to design and install a robust below-ground attenuation system to manage stormwater runoff from the extensive retail and car park areas at the new Cotswolds Designer Outlet as part of the site’s sustainable drainage strategy.

Context

The Cotswolds Designer Outlet is a landmark new retail destination, positioned at a prime location off Junction 9 of the M5 motorway near Tewkesbury. Phase one of the scheme delivers 136,000 sq ft of premium outlet retail space and food and beverage facilities for 56 leading brands. The outlet is operated by Multi-Realm and is set to attract up to four million visitors per year, serving a significant catchment between Birmingham and Bristol, as well as acting as a stop-off for tourists travelling to the Cotswolds. The wider development includes plans for 1,500 new homes, a 74,000 sq ft flagship Dobbies Garden Centre, business parks and travel-friendly amenities including EV charging, fuel stations and an M&S Food outlet - all contributing to a dynamic new destination for the region.

Objectives

To support the site’s long-term viability by ensuring the safe management of surface water runoff from the newly developed impermeable areas, minimising the risk of flooding and enabling compliance with planning requirements.

Requirements

With the introduction of substantial new built infrastructure across the site, the development required a surface water drainage solution capable of safely storing large volumes of stormwater runoff and discharging at a controlled rate to avoid overwhelming downstream systems.

In line with the requirements of the National Planning Policy Framework, the drainage scheme needed to incorporate Sustainable Drainage Systems (SuDS) to mitigate flood risk while supporting environmental and operational performance.

SDS product features

SDS supplied and installed a GEOlight® attenuation tank with a total capacity of 4,000m³, located beneath the development. GEOlight®’s modular structure allows rapid on-site assembly and provides efficient belowground stormwater storage without compromising space at surface level - ideal for constrained, high-value commercial environments such as this.

Manufactured from recycled plastic, GEOlight® also contributes to the sustainability goals of the project, aligning with Bouygues UK’s commitment to reduce carbon impacts and enhance environmental performance.

Challenges overcome

The introduction of extensive impermeable surfaces across the retail park, including roofs, roads and paved areas, significantly increases surface water runoff volumes. The SDS solution was required to integrate seamlessly with the wider drainage network and meet Local Authority requirements on flow rates and water quality, despite limited available space and ongoing construction.

Working closely with the main contractor, SDS ensured the tank’s installation was completed safely, efficiently, and in line with the programme to support the overall project timeline.

Result

The SDS GEOlight® attenuation system delivers reliable, long-term storage and attenuation of stormwater across the Cotswolds Designer Outlet. By maintaining discharge rates at pre-development levels, the system protects the development and surrounding watercourses from flooding and pollution. Its installation ensures the outlet can operate safely and sustainably, providing a positive experience for visitors while supporting the wider community and regional economy.

The successful delivery highlights SDS’s expertise in providing innovative, high-performance drainage solutions for complex commercial developments, combining resilience, sustainability, and operational reliability in a single integrated system.

Main construction commenced in early 2023 and the outlet officially opened to the public in July 2025.

Testimonial

"Partnering with SDS gave us the confidence that our new outlet centre would not only deliver a first-class retail experience but also meet the highest standards of sustainability. Their GEOlight® system provided the assurance we needed that the site would remain protected from flooding, allowing us to focus on creating a destination that benefits both visitors and the wider community."
– Ben Bowyer, Managing Surveyor, Bouygues UK