Why prefabricated pumping stations are the right choice

An introduction to proportional pressure in water boosting systems

Find out how proportional pressure benefits commercial buildings with more dynamic losses than static losses – such as airports, hospitals and shopping malls.

In this module, we’ll show you why installing prefabricated pumping stations is the right alternative to traditional concrete solutions. In short, prefabricated pumping stations are much more cost-effective, reliable and flexible than traditional concrete solutions.

Prefabricated pumping stations are supplied with piping, valves, auto-couplings, guide rails, pumps and level control. Ready to lower the pumps down to the auto-couplings. All these components are delivered by the same supplier as well as in the same unit, securing a cost-effective operation and ensuring that all parts fit perfectly. 

In contrast, building and installing a traditional concrete station from scratch is far more time-consuming. Moreover, concrete installations can crack over time, which creates leakages meaning that groundwater can enter the tank and while wastewater leaks out of it. Such leakages don’t occur in prefabricated pumping stations. Made of either corrosion-free polyethylene or glass-fibre reinforced polyester, the prefabricated pumping stations can avoid leakages for years, making it a much more reliable solution than its concrete counterpart. 

Both the time consumption and necessary repairs to the cracks result in a much costlier operation. Opting for a prefabricated pumping station lets you avoid these issues, demonstrating the cost-effectiveness of prefabricated pumping stations.

Grundfos offers two different types of prefabricated pumping stations: PS.R. and PS.G. The systems including the pumps are both CE-marked when delivered with piping, valves, guide rails, pumps and level control which saves you the trouble and cost of risk assessment. They do, however, differ in terms of size and features, so let’s take a closer look at them starting with the PS.R.

A solid shell is crucial for any successful pumping station, and the corrosion-free polyethylene of the PS.R provides just that. Polyethylene is highly resistant to aggressive liquids, which helps prevent cracks and leakages. This ensures a high level of reliability. One of the most unique features of the PS.R is its sump. Together with the ribs of the main section, the sump’s extended shoulder design ensures that the pump station avoids buoyancy even without a concrete foundation. 

Compared to other stations, the PS.R merely needs a gravel foundation, which with regard to installation makes it the most cost-efficient solution. Additionally, the sump is designed with self-cleaning properties, which helps reduce the sediment of sludge and odour thereby minimising maintenance costs.

In terms of size, the sump provides a diameter of 1700mm giving the necessary space for installation of two submersible wastewater pumps on an auto-coupling system with pipes and valves.

Grundfos offers the choice of three different pipe systems for the PS.R. pumping station:

- A pipe system with direct outlet

- A pipe system with goose neck

- And a pipe system for the valve chamber 

And if these standard solutions don’t fit your needs, Grundfos offers customised modifications."

High quality valve chambers are also part of the package when selecting a PS.R. One of the main benefits of a valve chamber is that you’ll avoid having to enter the wastewater station if the valves need to be inspected and operated. Apart from being a practical solution, it’s also a more environmentally friendly one.

Once you’ve decided on the PS.R, it’s time to install it and connect the inlet pipes by means of a hole drill and rubber profile sealing. First of all, it’s crucial to place the pit on a foundation layer of, for instance, gravel if soil analyses show that the soil isn’t capable of bearing the weight. Secondly, it’s important that the bedding layer is compactable and composed, so it doesn’t cause any damage to the pit. This means that the material must not be frozen or, for instance, contain traces of sharp flint or other damaging particles.

Finally, the backfill must be compacted in layers of max. 30 cm – corresponding to approximately 20 cm after compaction – in order to provide a sufficient level of support on all sides, ensuring that the load can be transferred without detrimental impacts. If this step is ignored, you’re running the risk of damaging your station.

The same instructions should be followed during installation of the valve chamber. So now that you’re acquainted with the PS.R, let’s turn our attention to the PS.G. A PS.G pumping station is made of corrosion-free glass-fibre reinforced polyester, exceeding the lifetime of a traditional concrete pumping station by far. With a diameter of 1200 to 3000mm it can provide a much larger amount of space than the PS.R and therefore it is also prepared for bigger pumps, highlighting one of the main differences between the two. Another significant difference is that it needs to be locked to a concrete foundation slab by means of brackets and bolts, in order to prevent buoyancy.

A PS.G pumping station is characterised by its robustness and customisability. The sheer size of the PS.G allows for several optional features such as baffle plates, screen baskets, access hatches and service platforms, demonstrating the ability to customise the station according to needs.

When it’s time to install the station, you merely need to follow the same installation process as we outlined for the PS.R. The only change is its use of a concrete slab on a levelled bottom filled with a foundation layer, rather than just gravel as a bedding layer. Even though the PS.R. and the PS.G. differ in many areas, they do share several features. One example is the covers for traffic.

The traffic covers are approved according to EN124 class D – carrying traffic load up to 40 tonnes – and come in several versions. One version features a concrete ring, an extended cover and a steel hatch. In this installation, it’s perfectly acceptable for the concrete ring to be visible at the top. Such an installation is easy, meaning that this version is the slightly more cost-effective solution. 

There is, however, a more advanced version. It’s a similar installation, but without a visible concrete ring at the top. Instead, a floating cover at the top means that it can be adjusted to level with the asphalt. At the same time, such a solution means that it can be adjusted when new asphalt is laid.

Now that you’re familiar with both stations, which one should you opt for? Well, there’s actually no fixed answer as such. It mostly depends on the individual advising engineer and the location. Both prefabricated pumping stations can be customised according to your needs. Therefore, they’re ideal for almost any requirement, regardless of the complexity. Grundfos can help you make the right investment.

By using Grundfos Pumping Station Creator, you can design your station in a matter of minutes. Here, you’ll be able to specify size, features and functionalities, while choosing from a wide range of pumps, controls, pits, valves and much more.

So, let’s recap some of the main points we’ve established in this task. Prefabricated pumping stations are:

- Easy to install

- Cost-effective

- Reliable

- Customisable

Along with the smart built-in functions, these features underline just how good a solution a prefabricated pumping station is.