ViaCon Storm Solutions

A attenuation tank for stormwater is engineered to gather and retain surplus surface water runoff during significant storm events. Subsequently, the water is discharged from the storage tank at a regulated pace, typically through a controlled flow mechanism.

Underground attenuation tanks are indispensable for urban stormwater management, mitigating the effects of heavy rainfall on local communities and the environment. They play a pivotal role in preventing flooding, erosion, and water pollution, while fostering more effective and sustainable water resource management practices.

During periods of heavy rainfall, stormwater attenuation tanks collect and store excess rainwater runoff from impermeable surfaces such as roofs, roads, and parking lots. The stored water is then slowly released into the drainage system or nearby watercourses through an outlet pipe or controlled release mechanism. This controlled release helps alleviate pressure on downstream drainage systems and reduces the risk of flash flooding.

Determining the size of an underground attenuation tank involves considering various factors, such as the site’s location, depth of the drainage system, storm return period, soil type, and infiltration rate. Location plays a crucial role in estimating the average annual rainfall in the area.

Our attenuation tank installation process is engineered for speed, efficiency, and reliability, significantly reducing on-site complexity and project timelines. The process follows a clear, structured methodology from delivery to final commissioning.

Step 1: Site Preparation and Delivery
The process begins with the prepared excavation site. Our tank components, including any factory-fitted accessories like access shafts, ladders, and inlet/outlet connections, are delivered directly to your site, ready for immediate assembly. This minimizes the need for extensive on-site fabrication.

Step 2: Excavation and Placement
A suitable site is excavated according to the project specifications. The lightweight, modular components of the tank are then placed or lowered into the excavation. This straightforward “set-in-place” method is a key reason our installations are up to 80% faster than traditional cast-in-place solutions.

Step 3: Assembly and Backfilling
Once in position, the tank components are secured. The area around the tank is then carefully backfilled with suitable material to secure the structure and ensure its long-term stability and load-bearing capacity.

Step 4: Connection and Commissioning
With the tank securely in place, it is connected to the existing upstream and downstream drainage systems or natural watercourses. The final step involves calibrating any flow control mechanisms to the precise discharge rate required for the site, ensuring the system performs optimally from day one. This streamlined process ensures minimal disruption and a fully functional system in a fraction of the time.

Yes, absolutely. A rainwater attenuation tank can be designed as a dual-purpose system. In this configuration, a portion of the tank’s volume is dedicated to retaining a permanent store of water for harvesting and reuse (e.g., for irrigation or flushing toilets), while the remaining volume is kept empty to provide the necessary capacity for attenuation during a storm. This combined approach offers the benefits of both flood prevention and sustainable water conservation in a single, efficient solution.

An attenuation tank temporarily stores excess stormwater and releases it at a controlled rate into the drainage network or watercourse, whereas a soakaway allows collected water to infiltrate directly into the surrounding ground. The key distinction lies in the discharge method: attenuation tanks use a flow control device to regulate outflow, making them suitable for sites with poor ground permeability or where a connection to an existing sewer is required. Soakaways rely on adequate soil infiltration rates and are typically used where ground conditions permit. In many SuDS designs, both systems can be combined to provide attenuation and infiltration within a single scheme.

Common issues with plastic geocellular attenuation tanks include structural collapse under heavy traffic loads, silting and blockage of cells reducing effective storage volume, and degradation of polypropylene over time. Poorly installed plastic crate systems can also suffer from geotextile membrane failure, allowing fine sediments to enter and clog the system. Steel attenuation tanks from ViaCon largely avoid these problems: corrugated steel provides superior load-bearing capacity, the smooth internal bore prevents sediment build-up, and the tanks can be inspected and jetted through standard manholes. With a design life exceeding 100 years and full structural calculability to Eurocode standards, steel tanks offer a more resilient long-term solution for demanding infrastructure projects.

Attenuation tanks are most commonly manufactured from either polypropylene (plastic geocellular crates) or corrugated steel. Plastic crate systems consist of modular units wrapped in a geotextile membrane and are typically used for smaller domestic schemes. Steel attenuation tanks, such as those manufactured by ViaCon, use galvanised corrugated steel pipe sections joined together to form large-volume underground storage chambers. The galvanisation process provides long-term corrosion protection, while the corrugated profile gives the steel exceptional structural strength relative to its weight. Steel tanks are the preferred choice for highways, commercial developments, and projects where the tank will be subject to significant traffic loading or where a design life of 100 years or more is required.