In addition to the need to minimise the impact of extreme flooding events, a much more sustainable approach to managing surface water is necessary in order to create a more balanced and natural ecology, in both our urban and rural areas.
By embracing the core principles of SuDS, we help to minimise the impact of flooding whilst also facilitating a much more attractive and sustainable landscape in which to work and live.
The advantages of geosynthetics in SuDS
For more than 50 years, geosynthetics have been used extensively throughout the world, helping to deliver innovative and cost-effective solutions across a diverse range of civil engineering problems. Their use offers many advantages over ‘traditional’ construction techniques. As a consequence, both the structural and stormwater treatment benefits of geosynthetics have been recognised and universally adopted in the development of SuDS solutions that deliver source control – both above and below ground.
All the stakeholders in any new development have a collective duty of care to deliver a CDM compliant solution, and one of the primary benefits of incorporating geosynthetics is that a more sustainable, shallow solution can be achieved which minimises both the risk and cost of construction. This reduced depth of construction also limits the use of natural materials and off-site disposal, which optimises the environmental credentials of a project.
Another prime benefit in the use of geosynthetics is their ability to enhance the water treatment capability of a SuDS system. Source control solutions rely upon a series of treatment stages in order to achieve an acceptable quality of discharge water, and geotextiles and geocomposites in particular have an important role to play in achieving this increasingly onerous requirement.
Green and blue roofs and podium decks
ABG green and blue roofs (constructions that have the ability to attenuate collected water within the roof/podium deck structure) have been used extensively across many leading sustainable developments across the UK. Offered as a full turnkey solution, including PI covered design through to installation and on-going maintenance, they provide an integral element of any holistic SuDS solution.
The final design of the system is dependent on the project specific requirements, with a number of final surface finishes available including extensive, intensive and biodiverse vegetation along with paved finishes. The drainage/storage capacity is also project specific to meet the requirements of the SuDS design. A blue roof is often more cost effective than a SuDS tank. Geosynthetics are an integral element of green and blue roof construction, allowing the build to be thinner and lighter, whilst maintaining building performance. The use of geosynthetics contributes to the drainage and storage capacity whilst having a positive impact on quality of water discharged from the roof.
Trench soakaway systems
Geotextiles have long been an integral element of soakaway systems, providing a vital treatment process as collected water is filtered through the fabric. They provide a separation function of granular stone layers and filtration of water within the drainage systems to reduce the environmental impact of construction. They are an important component in many applications, including in the construction of roads, car parks, embankments and wrapping SuDS Infiltration/Attenuation Tanks.
Swales and channels
Geosynthetics can contribute to the construction of efficient swales and conveyance channels, by providing resilient protection from damage caused by erosion. The use of geosynthetics enables steeper banks to be constructed, reducing the land-take required and freeing up valuable space for development.
ABG offer a broad range of erosion control products, including biodegradable and non-biodegradable erosion control mats. They can help with the surface protection of many elements within the SuDS scheme including swales, channels, ponds and attenuation basins. Erosion control systems help ensure the environment is protected throughout the life of the project from construction to establishment of the vegetation. As with all ABG products, design advice on which materials are best for your specific requirement and their specification is available from the SuDS technical team.
Underground geocellular tanks
Geosynthetics are an integral element of geocellular tanking systems; geotextiles can form a highly efficient filtration material in infiltration systems, whilst geomembranes make effective tanking systems where attenuation is required.
Source control utilises several elements to attenuate and treat the rain water. Geocellular SuDS tanks have 98% void space and therefore minimise excavation. Once buried, they can be trafficked in accordance with CIRIA guidelines. The tanks are supplied as easy to assemble components. For infiltration tanks, a filter geotextile is placed around the tank. For containment the tanks are constructed within a geomembrane liner. The SuDs tank is used in conjunction with a vortex control chamber to limit the discharge to the rate set by regulation.
Ponds and basins
Geosynthetics provide a convenient method for the effective lining of SuDS retention ponds and basins. Where suitable, steep banks can be constructed using geosynthetics making more land available for development. Geosynthetic lining systems such as GCL and HDPE are useful and long-lasting methods of forming ponds. Liners can be pre-fabricated to size before delivery, or welded on site to the required profile.
Vegetated retaining walls
The Webwall geocellular retaining wall system offers a neat and fast to install solution in many SuDS applications, with its primary use being in the construction of steep embankments on SuDS structures such as swales, channels and attenuation basins and ponds. Constructing steeper embankments minimises the land-take of the structure, freeing up more land for development and allowing developers to maximise return whilst meeting statutory SuDS requirements.
Porous paving systems
Geosynthetics are integral to the successful function of porous paving systems, allowing pavements to be constructed using less imported stone, improving water quality by their filtration and allowing pavements to be used for the infiltration/attenuation of collected surface water.
ABG offer a range of complementary components to create an integrated porous paving system, designed to effectively manage the safe collection, treatment, management and dispersal of surface water. The ABG Sustainable Paving system is configurable to individual project requirements and offers a range of surface solutions to meet aesthetic and performance requirements.
A range of geogrids and geocells can both minimise construction depths and meet structural requirements. In addition, high performance geotextiles help treat collected water to meet quality expectations.