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Comparing Sandbags with Plastic Flood Barriers

As the seasons change and wet weather descends on the UK, it’s time to be proactive about flood defence. As highlighted by the National Environment Research Council (NERC), UK winters are becoming significantly warmer and wetter, as clearly demonstrated across the many areas of the UK which suffered extreme flooding throughout  the winter of 2016-2017.

An added complication occurs when, as in many areas of the UK, homes have been built on flood plains. Removal of natural barriers such as hedgerows and woodlands puts homes and businesses in these areas at additional risk of flooding.

Aside from the need to take individual and collective responsibility for reducing climate change, individual homes and businesses also need to be proactive in helping to prevent flood damage when the worst happens. But which is the best way to do this? Do sandbags still have what it takes, or is it time to ditch the traditional and manage extreme flooding with more robust prevention, such as plastic flood barriers?

Flood defence barrier 500mm deployment

Sandbags – a traditional tool

We’re all familiar with the image of sandbags for defence, particularly against flooding – most news images of the UK’s extreme floods in recent years have shown them in use and this is because they traditionally offer several distinct advantages, being:

  • Cheap to create and transport.
  • Easy to supply across wide areas when responding to flood risk.
  • Useful as a first line of defence at high-risk locations, such as river banks. Whilst sandbags may not prevent the worst from happening (such as the river bursting its banks) this type of deployment can often give householders and businesses that vital extra time they need to implement their own defences against flooding.

Sandbags as flood defence

Sandbags – not always the solution

However, sandbags have a limited effect when it comes to providing a solution for flooding – at best they may delay the inevitable and at worse, they may even exacerbate issues such as health risk as flood water subsides. Common problems with using sandbags as flood defence are:

  • They can be tricky to set up and, once filled with sand, do involve a level of physical labour to create a barrier. Then of course, once their work against flood waters is completed, they can be extremely heavy and difficult to remove safely and with minimal risk of personal injury.
  • Ineffective for groundwater flooding as it is relatively easy for liquid to seep through and underneath, especially if they have been quickly and inexpertly stacked or have been subjected to a sudden deluge.
  • Although the sand inside sandbags could theoretically be reusable, in practice it’s not advisable that sandbags which have been deployed against flooding should be reused. This is because flood water is often contaminated, for instance by sewage products, as burst or overflowing sewers and roadside drainage can often be involved in localised flooding. As such, sand becomes contaminated with bacterial and viral hazards, with the bags themselves rotting as flooding subsides- creating a hazardous area and rendering the sandbags unsuitable for recycling for future use.
  • Similarly, where such contaminated water seeps through the sandbags or enters the property by other means, the slurry tends to collect at ground level when the water subsides, rather than filtering back through the sandbags, so the slurry is trapped inside the property, rather than kept away by the barrier.

As such, and as flooding in the UK has made the headlines frequently in recent years and particularly in 2016 (BBC News), the overall effectiveness of sandbags against flooding has been called into question.

Plastic barriers – improved protection

Flood defence barrier 500mm

Like sandbags, plastic flood barriers offer a simple design: modular plastic barrier units with self-filling holes which retain flood water. Available in two sizes, 500mm and 900mm, plastic flood defences offer plenty of options for deployment in relation to level of risk.

However, unlike sandbags plastic flood defence barriers can be extremely effective, not just when it comes to flood prevention but across the whole flood duration:

Before – can be quickly deployed, even at short notice and even by one person as required. Runs of barriers can be assembled to face any direction, with opening as appropriate to maximise effectiveness.

During – as waters rise, these hollow modular barriers actually fill with flood water. Working alongside in-built weighted universal keys, it’s the weight of the flood water which helps to keep the barriers in place without bolting.

After – as flood water recedes, the water in the units simply drains away so that the barriers return to their previously empty state, light enough to be removed with the same ease with which they were deployed.

Flood Defence Barrier

With this very fit-for-purpose specification, plastic flood barriers offer several distinct advantages, offering:

  • Ease in setting up – by just one person if necessary.
  • Highly flexible deployment options.
  • Innovative self-balance design, with no need to bolt to the ground.
  • Retention of the flood water, which drains out of the barrier as the flood recedes.
  • Cost-effective as they may be reused multiple times, unlike sandbags
  • Easy storage when not in use as empty barriers can nest inside each other.
  • Connectivity, to create any length required without leaks.
  • A variety of available hub ends , to create curves and corners.
  • Fully recyclable and reusable – although they can ‘hold’ flood water inside, unlike sandbags, the plastic construction doesn’t actually absorb any fluid. So, once the water has subsided, they can rinsed as required, ready for future use.

In fact, one of the very few drawbacks to using plastic flood barriers is that their innovative design is for optimum performance on relatively flat surfaces, to allow them to be fully effective in creating a ‘seal’ against rising flood waters. However, this too can be a similar issue for sandbags which may also not sit well on undulating ground and frequently allow seepage. Given that part of the flooding problem in floodplain areas is that this is flat land close to rivers and waterways, plastic flood barriers could be an effective solution.

Finally, another benefit of plastic flood defences comes because, unlike sandbags, they can be an approved preventative measure with some flood insurers. Now this won’t necessarily mean cheaper flood insurance but it can, in some areas and with some insurers, make a difference between being able to get insurance or not.

To also help with costs, it may also be possible to hire, rather than purchase plastic flood barriers from SafeSite Facilities, perfect for use across the wettest UK season! Just contact us to find out more.

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