Managing waterlogged sites in the winter

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Managing waterlogged sites in the winter - SERV Plant Hire

Managing waterlogged sites in the winter is vital to avoid delays, minimise lost work hours and keep construction workers safe. British weather is notoriously unpredictable, with a high level of rainfall, especially during the winter months. If the correct precautions are not taken, waterlogged ground can quickly make a site unworkable, bringing work to a complete halt. Not only will this cost money, with workers and equipment (especially hired plant) standing idle, it can strain relations with customers. Few customers are likely to be sympathetic to delays caused by a lack of preparation and poor site management.

Waterlogging occurs when soil becomes saturated with water that cannot drain away. This can be caused by sustained rainfall, flash floods, high local water table or inadequate slope for drainage. During the winter this is compounded by cold temperatures lowering the rate of water evaporation and slowing drying times. If the temperature drops further any standing water will then freeze, bringing added hazards to the worksite. The Health and Safety Executive website has full details of the responsibilities of site managers in providing a safe working environment.

Hazards of waterlogged sites

1.      Flooded trenches.

Trenches that have filled with water are inconvenient and dangerous. Water will have to be removed before work can proceed and they are prone to collapse. Not only will this slow work as they are dug out again, but any workers in the trench could be crushed, suffocated, or drowned.

2.      Weakened foundations.

Concrete must be mixed to specific ratios and if extra water gets into the mix not only will it be slower to set, but the end result will also be weaker. Consequently, foundations laid in wet soil could be incapable of supporting the weight of the structures built on top. This could lead to collapse, putting workers or future occupants of the building at risk. At the very least, the building and foundations would have to be demolished and completely rebuilt.

3.      Difficulty operating machinery.

Waterlogged soil can cause heavy machinery such as excavators or dumpers to lose traction and slip or possibly overturn. This poses a risk to the operator, pedestrians and anybody working nearby and could damage the machinery itself. The weight of the equipment can also cause it to sink and become bogged down. It will then be unusable until it is dug out, possibly requiring additional equipment not in the original budget for the project. Combined with the already lost work hours, this can drive the budget of an otherwise simple project up considerably. Even if these hazards are avoided, extra care will need to be taken at every stage, slowing work, and causing operator fatigue.

4.      Slipping.

The slippery, slick ground surface can make a task as simple as walking around the site slow and dangerous. Just falling on wet soil can leave the worker wet, cold and at risk of hypothermia unless their clothes are changed. If they fall onto hard surfaces or against site equipment, serious injury is likely. Slipping while operating handheld equipment is not only dangerous, the equipment could be damaged or broken leading to costly repairs or replacement.

5.      Damage to electrics.

If water penetrates the casing of electrical equipment it can damage the components and prevent the equipment from working properly. This can also increase the risk of electrical shock to operators during use. Electrical supply cables that have been immersed in water due to flooding can potentially pose a lethal electrocution risk to workers or site visitors.

6.      Freezing.

When the water present in waterlogged soil freezes, it becomes an even greater slipping hazard to pedestrians and vehicles. Injury from falls and damage to equipment is even more likely due to the harder ground surface. Frozen soil is extremely difficult to dig, if not impossible, leading to delays or work being abandoned until it thaws.

7.      Damage to materials.

If a storage area floods, any dry materials such as concrete or plaster could absorb water, making them unusable. Wood will also absorb water, causing splitting, warping and decay and leaving the timber open to fungal infection.

Dealing with a waterlogged site

Whether a site becomes waterlogged during construction work or is already waterlogged before work begins, the same remedial measures apply. The whole aim of the process is to remove water from the ground and there are several tools that will speed this process up. For extremely wet areas such as marshland, specialist techniques and materials may be needed. As a result, dealing with these conditions is best left to experts. For almost all other sites, the following methods and equipment should suffice.

1.      Drain all flooded areas.

If trenches or other excavations have been flooded, the water will need to be removed before work can continue. Excavator buckets can be used to quickly remove most of the water, with their large capacity speeding up the process considerably. The remaining water can then be drained using a Submersible Pump. As the name suggests, these can be completely immersed in water and rapidly pump it through an attached hose and out of the trench.

2.      Remove surface water.

Any large puddles or pools can be removed using a Puddle Sucker Pump. These stand in shallow pools of water and suck the liquid up through their base, pumping it away for drainage.

3.      Construct temporary drains or deep wells.

Once all standing water has been removed, this will prevent it returning. A deep hole is excavated and water in the ground drains into the hole to be pumped away. This lowers the water table in the vicinity, allowing foundations to be safely excavated and concrete poured without any chance of ground water contaminating it. As the water in the drain will contain a lot of soil, a diaphragm pump is recommended for its removal. These are designed to pump water containing mud, soil, and other small particulates without clogging or jamming.

4.      Dry indoor areas.

After surface water has been removed from interior floors, an industrial dehumidifier will remove water vapour from the air, including final traces from the floor as they evaporate. This guarantees a completely dry area for storing materials that could be damaged by moisture.

SERV Plant hire are plant and machinery specialists offering a huge variety of construction equipment and tools for hire to the North West of England. We have a wide range of specialised equipment for all your winter construction jobs, from submersible and puddle sucker pumps to diaphragm pumps and hoses. For all the equipment needed to complete your project safely and efficiently, contact us, we will be happy to help.

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