Stormwater tank by Uponor

Stormwater management: why tanks beat cassettes

Stormwater tanks – the superior solution

Stormwater tanks suit for many needs

In an era of growing infrastructure demands and heightened environmental awareness and requirements, choosing the best stormwater systems takes careful consideration. As a leading provider of stormwater solutions, Uponor strongly believes that the advantages of tank and pipe -based solutions are clearly superior in almost all large-scale scenarios compared with solutions such as cassette-based ones. The reasons are many – and are based on both functional and qualitative aspects, as well as their total cost of ownership.

Infiltration or attenuation?
Infiltration solutions for stormwater management attenuates storm water runoff for a short period and allows it to naturally infiltrate to the ground on location. They are ideal for relatively clean storm water, for example when managing runoff from roofs. Additionally, they are suited for projects where soil conditions are good, and where it is possible to install it above the ground water level. Attenuation systems are often best in situations where controlled discharge into the network or recipient is required to prevent flooding, where the local water table is high, and/or when the water’s quality requires efficient treatment before discharge. In both these scenarios, Uponor tank and pipe -based solutions are superior to conventional systems that are still used today by many contractors.

Infiltration pipe solutions – clear advantages

Uponor infiltration pipe systems offer significant benefits compared with traditional cassette solutions. Each Uponor pipe solution is custom designed for the specific demands of the project, and the pipes are backfilled with  gravel, which optimizes the system’s ability to soak the water naturally into the ground.

Faster installation
Because Uponor infiltration pipe systems are pre-fabricated they are significantly faster to install than for instance cassette solutions – which means less labor costs and less disruption of the worksite. The minimum backfilling requirement is just 30-50 cm, and, where allowed, reuse of backfill material is possible.

Much easier to inspect and maintain
Significantly, an infiltration-based pipe solution is more robust and longer lasting than other conventional solutions. Not only are pipes much less vulnerable to damage caused by settling than – for instance – cassettes may be, they have already been proven through extensive use by contractors. As importantly with regard to delivering a long lifetime of use, is that their internal open structure means much less chance of clogging and allows for easy inspection through risers or man holes, for repair, emptying and cleaning (if needed). A partial renovation of the system can even be done without excavation, and with normal maintenance, an estimated lifespan of 100 years is reasonable. The modularity of the system makes extensions both possible and easy to install.

Uponor tank systems offer significant benefits compared with traditional cassette solutions.

Attenuation tank – the modern solution

The pump station made by Uponor Infra is the largest prefabricated structure in Sweden, at 23 metres long and with dimensions of ID/OD3,500/3,900mm.

Uponor’s attenuation tank solutions offer many of the same advantages over cassette systems that their infiltration solutions do – and more as well. Not only is each attenuation tank designed based on the unique requirements of the project, but features the possibility of integrated flow regulation, eliminating the traditional need for a separate chamber.

Just as with their infiltration solutions, Uponor’s attenuation tanks are less vulnerable to ground settling, won’t clog easily and can be cleaned and maintained safely and efficiently. Additionally, the fully watertight  tanks can be used in areas with high ground water thanks to their robust structure and dependable jointing methods.

A better solution – with a lower total installed cost
Even though the manufacturing costs for Uponor’s infiltration pipe and attenuation tank solutions are higher – due to their customized pre-fabrication and more robust, durable materials, the final installed cost is actually less than with traditional cassette solutions.

Comparison to cassettes

A real project comparison of a typical (120m3) attenuation system in a completed project with excavation cost excluded shows how Uponor’s pipe and tank solutions are actually less expensive. Of course, costs will vary depending on the specific demands of a project:

  • Installed cost of cassettes:  €36,250
    Installation hours required: 91h
    Attenuation volume: 120m3
  • Installed cost of tanks:  €33,531
    Installation hours required: 40h
    Attenuation volume: 120m3
Hulevesien varastoinnissa ja viivytyksessä hulevedet johdetaan suuriin säiliöihin, joista ne päästetään painovoimaisesti tai pumpulla pikkuhiljaa eteenpäin viemärijärjestelmiin tai purkupaikkaan.

Factors that drive your solution

As mentioned, every project is unique, and a number of factors need to be kept in mind when making your stormwater management solution decisions. These may include everything from the stormwater network’s condition and local ordinances, to soil conditions and whether the area is industrial, residential or commercial.

What’s clear is that a stormwater tank and pipe solutions can be chosen for a quite similar installed cost – and will also deliver a range of additional benefits over traditional systems.

As mentioned, every project is unique, and a number of factors need to be kept in mind when making your stormwater management solution decisions. These may include everything from the stormwater network’s condition and local ordinances, to soil conditions and whether the area is industrial, residential or commercial.

What’s clear is that a stormwater tank solution can be chosen for a quite similar installed cost – and will also deliver a range of additional benefits over traditional systems.

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