STORMS PRESENT A REAL RISK TO FARMERS AND GROWERS WHO USE POLY-TUNNELS SO IT IS NECESSARY TO ENSURE A SAFETY MANAGEMENT PLAN IS IN PLACE

High winds can prove particularly damaging to tunnels which means weekly inspections should be carried out to ensure the integrity of the structure is maintained. Pay close attention to the upper section near the apex of the tunnel – if you notice any kinking then this should be rectified as it can increase the likelihood of collapse of that section of hooped tubing.

Replace any damaged sections immediately to ensure the structural strength of the frame.

Solid and stable

A solid poly-tunnel should include horizontal and apex bracing to each hoop as this will reduce the risk of collapse.

There should also be extra strengthening at the tunnel ends, for example, double-hooped gable ends on the first hoop section. As well as this, the second and third hoop sections should be tied to each other to share any stress.

The hoops to the exposed flank of the tunnel, facing the prevailing wind, must be inserted deeper into the ground for greater stability. And wire ridge bearers must be linked to the tunnel tubes and there should be additional bracing at the ends.

There must be quality taping over the out face of the hoops where it is in contact with the skin to prevent chaffing and rubbing.

Monitoring the forecasts

Keeping an eye on the weather forecast is an obvious way of being ready for poor conditions. By monitoring the forecasts it is possible to have an understanding of which way the wind will be moving and therefore which parts of the site will be most affected by the weather.

On a daily basis the field weather stations should be studied and a senior member of staff should continue to monitor throughout the day.

It isn’t just wind speed that affects the tunnels. It is important to look out for low pressure systems travelling north or south and/or a high level cell (large depression) as this creates short violent bursts of wind on the perimeter of the depression. This can have most impact on the tunnels.

Immediate action should be taken where necessary.

Weathering the storm

If high winds are expected on a short term basis, fully venting the tunnels is advisable. Any staff should be trained so that they are able to vent the tunnels when required.

The tunnels must be vented in poor weather. Polythene should be rolled up to the height of the ridge reducing the flank exposure to the winds and heavy rains. Once the weather has passed and the forecast is clear, the skin can be reapplied and secured.

However, if a longer storm is forecast the tunnels should be completely de-skinned.

For more information speak to your local NFU Mutual Agent.