Trench collapse or cave-in accidents happen very often. In fact, in 2016 alone a record of 72 workers involved in cave-ins, and most of them died while doing their work. And this is just one of many records of caught-in incidents which averaged around 54 deaths from 2000 to 2006.
The injuries sustained can be very traumatic and it can be permanent. Some may even result in fatalities. So in order to prevent these accidents, confined space safety measures must be undertaken to protect workers while doing their job.
Read more as we are going to discuss the dangers of trench collapse and some tips on how to prevent this accident from happening.
Know The Facts
The fatality rate of excavation jobs is 112 percent higher compared other construction-related jobs, which is why so many injuries (and fatalities) are the cause of this.
Most of the reasons why cave-in or caught-in accidents occur are:
- Allowing workers to perform their duties without proper protection.
- Failure to provide a safe method of entering and exiting the trench.
- Not having a certified engineer/professional to inspect the trench for potential hazards.
- Not being able to check the soil on the ground.
Soil Identification Can Be A Crucial Factor In Trench Collapses
There are many different factors that contribute to cave-ins and these are the soil type, the soil’s weight, the soil’s moisture content, the vibrations on the ground, and the weather of the area where the trench is located, but what’s similar about these factors is that they all point out to one important element: the soil.
Soil is usually classified according to stability. The most stable of which is the stable rock and then followed by Type A, B, C (in decreasing order):
Stable Rock – A rock formation that is made up of solid materials which is ideal for trenching since the walls are very stable. Also, it will be able to withstand the forces of nature when the soil is exposed to the weather.
Type A – This type of soil is fairly stable and should not be subjected to on ground vibrations. Additionally, the ground should not be previously disturbed otherwise it will be automatically downgraded as Type B.
Type B – This kind of soil typically includes angular gravel. It is somewhat cohesive but has low impressive strength. Similar to Type A, it should not be previously disturbed or it will be automatically downgraded to Type C.
Type C – Commonly referred to as “farmer’s dirt”, this type of soil is a combination of sand, loam, and loose gravel. Type C soil can be cohesive but can be unstable when exposed to weather.
In earthwork operations, the Occupational Safety and Health Administration (OSHA) specifically require that all soil or rocks to be excavated should be classified by a certified expert first. This person will perform a test to indicate the type of soil they are dealing with and if it can be able to “stand-up” to its own weight. The result of the test will not only classify the type of soil but will also help the expert to determine which kind of trench to make according to the soil type. The more unstable the soil, the more angled are the trench walls to prevent trench collapse.
If in case you are going to dig a trench with vertical walls on a less stringent soil, it is always recommended to install a safety measure like a trench box to keep the workers safe and to avoid the company from being fined.
More Tips To Prevent Cave-In Incidents
Lastly, here are some important tips from OSHA that you need to remember:
- Any excavation more than 5 feet should require a protective system like a trench box that is pre-approved by a certified engineer.
- Any trench deeper than 4 feet should require a safe entry/exit points within 25 feet from the workers’ position.
- Trench conditions should be inspected by a “competent person” on a daily basis.
- Be extra cautious from water and mud during and after rain.
- Be aware of low oxygen levels and toxic fumes.
- Always inform workers never to assume that there is enough time to move out if a trench collapse starts.
- Use cones, signs, and any other equipment to notify other workers in the construction area about the location of the trench and that trenching is going on.