Do flash floods wreak havoc on your property during heavy periods of rain?
Soakaway crates are often used in areas where the ground is covered by impermeable materials such as tarmac, block paving and concrete. This includes roads, pavements, car parks and large roofed areas.
Many years ago, soakaways were large pits filled with gravel, stone and hardcore. However, over time, bits of soil ended up being washed down into the openings between the coarse material, filling the empty spaces and rendering them useless.
Modern-day soakaway crates are modular, meaning you can stack them on top or next to each other and dig a much smaller hole.
Unsure how many soakaway crates you need? Many people often struggle with the installation of soakaway crates. Let us explain everything you need to know – including how to determine the right size and number of crates.
7 simple steps to install soakaway crates
1. Decide where to install your crates
Ideally, soakaway crates should be sited in sandy or loamy soils, as opposed to heavy clay soils that don’t allow water to percolate into the ground. The perfect spot for your crates is at a lower level than your building, or at least on the same level.
Whilst you need to make sure the ground conditions are suitable, it’s also crucial that the soakaway is at least 5m away from your home or any other nearby buildings. This is to ensure you don’t disturb the foundations.
2. Calculate how many soakaway crates you need
The beauty of modular soakaway crates is that you can combine them to create a system that’s as big as you need. However, you still need to work out how many you require.
The overall size of your system will depend on the amount of space you have available, the soil type and the expected flow rate of surface water. It’s a good idea to ask a groundworker to perform a percolation test to determine the ground conditions.
To make matters even more confusing, different manufacturing brands provide crates in various sizes. As a general rule of thumb, you’ll need 5 Polypipe Polystorm soakaway crates per m³ or 2.28 ACO StormBrixx crates per m³.
3. Dig a trench
Once you’ve figured out where your soakaway crates will be sited and how many you need to build your system, the next step is to dig a hole – big enough for the crates, top, side and base fill of gravel and sand.
Take your time when excavating. If your soakaway is to go in your garden, carefully remove the turf so you can use it again when the crates are in place.
4. Apply the base
At the bottom of the trench you’ve just dug, there needs to be a layer of sharp sand or pea gravel for the crates to sit on.
Once you’ve added the base fill, a geotextile membrane needs to be fitted to the inside of the hole before the crates can be lowered in. This membrane prevents the soil from being washed away into the soakaway, which was often the case with older soakaways.
5. Prepare the crates
Depending on where you buy soakaway crates from, you should get some clips or ties with them. These will come in handy for connecting the crates and preventing any unwanted movement when you’re adding the side fill.
After you’ve joined the crates – stacking them side by side or on top of each other – wrap them in the same geotextile membrane to maintain the performance of the system.
You can then lower them into the hole.
6. Connect the crates to the drainage system
Some soakaways have a separate section for the stormwater pipe to be fitted, but this isn’t the case with all systems.
If your crates don’t have a pipe entry point, don’t panic. It can be placed next to the crates and held securely in place with the side fill. Which leads us on to the next step.
7. Add the side and backfill
Now your soakaway crates are in place and connected to the drainage system, you can start to backfill the trench using 150m of sand or pea shingle – covering all around the sides and on top of the crates.
At least 150mm of the excavated soil can then be shovelled back and tamped down, before re-laying the turf that was removed.
Want to know more?
If you have any questions about soakaway crates or need assistance installing them, contact the experts at Build Plumb Plastics. Always on hand to help, they can guide and advise you to ensure you get the job done properly and efficiently.
Alternatively, if you’d like to buy plastic soakaway crates for your next project, be sure to take a look at their online range. They have plenty to choose from and guarantee affordable pricing.
