Are you planning to install attenuation tanks but unsure which materials will best suit your project? Attenuation tanks are essential for managing stormwater, preventing flooding, and supporting sustainable water drainage systems.
Typically, an attenuation tank is constructed using geo-cellular crates, impermeable geomembrane, and protective geotextile to create a watertight underground storage system. These materials work together to ensure durability, efficiency, and long-term performance in managing water flow.
In this blog, we’ll explore what materials are best for attenuation tanks, explain their roles in the tank’s construction, and guide you in choosing the best options for your specific project.
What is an Attenuation Tank?
An attenuation tank is an underground structure designed to temporarily store excess rainwater and release it gradually into the drainage system.
These tanks are an essential component of sustainable urban drainage systems (SUDS) and are commonly used in areas prone to heavy rainfall or where impermeable surfaces, such as concrete or asphalt, dominate the landscape.
Constructed using materials like geo-cellular crates, impermeable geomembranes, and protective geotextiles, attenuation tanks form a watertight storage solution that prevents surface flooding.
They are installed beneath driveways, car parks, or landscaped areas, ensuring they do not disrupt the site’s usability. Attenuation tanks play a crucial role in modern water management, helping to reduce the effects of urbanisation on natural water flow and reducing strain on public drainage systems.
What Does an Attenuation Tank Do?
An attenuation tank serves as a rainwater management system, capturing excess runoff during heavy rainfall and releasing it slowly into the drainage network. This function reduces the risk of flooding and prevents the local drainage system from exceeding its capacity.
By controlling the flow rate of stormwater, attenuation tanks help maintain a balance between rainfall and drainage capacity. This is particularly important in urban areas where natural infiltration is limited due to the prevalence of hard, impermeable surfaces.
In addition to preventing flooding, attenuation tanks contribute to environmental sustainability by promoting controlled water flow, reducing erosion, and minimising pollution. These tanks also support compliance with environmental and planning regulations, making them an essential part of modern infrastructure projects.
How Do They Work?
Attenuation tanks work by temporarily storing rainwater in a watertight underground structure before releasing it at a controlled rate into the drainage system. The construction typically involves geo-cellular crates, which create a strong yet lightweight framework to hold water.
These crates are wrapped in impermeable geomembranes to ensure the tank remains watertight and protective geotextiles to protect it from external damage. When heavy rainfall occurs, water is channelled into the tank via a connected drainage system.
The stored water is then released gradually through an outflow system, ensuring that the local drainage network can manage the load effectively. This controlled release prevents flooding, reduces pressure on infrastructure, and supports sustainable water management in urban and rural areas.
What Materials Are Best for Attenuation Tanks?
The effectiveness of an attenuation tank depends heavily on the materials used in its construction. Selecting the right combination of materials ensures the tank can handle environmental pressures while efficiently managing rainwater.
Geo-Cellular Crates
Geo-cellular crates serve as the core structural component of an attenuation tank. These crates are designed to provide a lightweight yet strong framework that can handle significant loads from the surrounding soil or surface above.
By creating voids within the structure, they offer enough storage capacity for rainwater.
Their modular design allows for flexibility in shaping and sizing the tank to suit different site requirements. Geo-cellular crates are also easy to transport and install, making them a practical choice for a wide range of projects.
Impermeable Geomembrane
The impermeable geomembrane is an essential layer that wraps around the geo-cellular crates, creating a watertight barrier. This membrane prevents water from escaping into the surrounding soil, ensuring that all collected rainwater is securely contained within the tank.
Typically made from durable and water-resistant materials such as polyethylene, the geomembrane is designed to withstand environmental pressures, punctures, and long-term exposure to water. Its role is important in maintaining the efficiency of the attenuation tank and ensuring proper water management.
Protective Geotextile
The protective geotextile is the outermost layer in the construction of an attenuation tank, protecting the geomembrane and crates from damage caused by sharp objects or debris in the surrounding soil. This layer boosts the durability and longevity of the tank by acting as a buffer against external forces.
Geotextiles are highly resistant to tearing and degradation, ensuring that the attenuation tank remains effective under varying environmental conditions. Their inclusion is crucial to maintaining the structural and functional integrity of the entire system.
Conclusion
Choosing the right materials for attenuation tanks is crucial for ensuring their efficiency, durability, and ability to manage stormwater effectively. Geo-cellular crates provide structural integrity, impermeable geomembranes ensure water-tightness, and protective geotextiles add an extra layer of durability.
Together, these materials form a reliable and efficient system that addresses stormwater challenges in both residential and commercial projects. Understanding these components allows you to make informed decisions personalised to your specific needs.
If you’re ready to boost your project with a high-quality attenuation tank, trust Resolute Civils to provide high-quality materials. Contact us today!
Frequently Asked Questions
What materials are commonly used in attenuation tanks?
Attenuation tanks typically use geo-cellular crates for structural support, impermeable geomembranes to ensure water-tightness, and protective geotextiles to protect against external damage.
Why are geo-cellular crates preferred for attenuation tanks?
Geo-cellular crates are lightweight yet strong, providing void space for water storage while maintaining structural strength under pressure.
What role does an impermeable geomembrane play in an attenuation tank?
An impermeable geomembrane creates a watertight barrier, preventing stored water from leaking into the surrounding soil.
What factors should be considered when selecting materials for attenuation tanks?
Considerations include load-bearing requirements, soil characteristics, environmental conditions, and the overall stormwater management goals.
Are there environmental considerations in choosing materials for attenuation tanks?
Yes, using sustainable materials or recycled elements can reduce environmental impact and align with regulatory requirements for eco-friendly systems.
What is the life expectancy of an attenuation tank?
Attenuation tanks can last for decades with minimal maintenance, depending on the quality of the geomembrane welds. The successful performance of the lining system is related to the goemembrane seam weld, which can be integrity tested during its lifetime.