Trenching and Excavation Safety

Trenching and Excavation Safety

the Occupational Safety and Health Administration is investigating that deadly trench collapse in Hudson our investigation found this steel frame box used to sure of trench walls was not used in the area where the workers were trapped and this 9-1-1 call from the scene confirms it these guys Medicaid and didn't have a bot kind of a morbid scene and they got two bodies down in hurt if we're unable to get to them that's not the outcome of what any of us want to have firefighters say that the men did not have a safe guard around the trench to stop the dirt from collapsing in on them a man who was repairing an underground sewer line became trapped about 12 feet down a track showing the weight of the dirt they weren't able to just pull him out because of the compressed dirt inside as well as the weight of it we are continuing with breaking news a man is dead after a trench Kalama son was trapped up to his neck in dirt OSHA the Occupational Safety and Health Administration has been on scene here the investigation is now under there a construction worker is recovering tonight after being trapped in a train fortunately rescue workers say the man was breathing and conscious as you in the back of an ambulance this after being buried in a trench that ran of 15 feet deep it's no secret that excavation work can be dangerous the Bureau of Labor Statistics reports that on average about 70 people die every year due to cave-ins from trenches add to that another thousand or so workers that get injured every year from cave-ins ninety-five percent of these incidents have one thing in common they were not properly safeguarded against and with so many other unpredictable dangers in the construction industry why expose yourself to injury leading a lost time or even the risk of death when there are clear and simple safety measures you can take to protect yourself in this video we'll cover key elements of an excavation as well as some important safety measures you can take to protect yourself these will help you determine whether an environment is safe to work in and if it's not what you can do to help make it safer for yourself and those working around you the first thing to consider with an excavation is soil conditions there are a variety of soil types and ground conditions that will determine the proper course of action for an excavation but before you start taking a closer look at the excavated soil look around the site for things that can cause soil distress like nearby vibrating machinery heavy moving loads seeping water or rain as well as hot dry weather all of these things can lead to additional stress on soil where increased precautions would be necessary one of the most important factors that can help determine the likelihood of a cave-in is the type of soil that you're excavating knowing the type of soil you're working with will help determine the proper slope of that excavation there are three main classifications of soil types a B and C type a is the most stable type and usually consists of clay if you don't have any of the tools used to determine soil type a quick way to figure this out is by taking a sample in your hand and pressing your thumb into it if your thumb sinks in only about a quarter of an inch you have type a soil with type a the slope of your excavation can be no less than horizontal for every four feet vertical if your thumb goes in about a quarter to three quarters of an inch you probably have type B soil this has a medium level of stability and can be made up of silt sandy loam or medium density clay with type b soil your excavation slope can be no less than one foot horizontal for every one foot vertical this type of soil can also include unstable dry rock or soil that's been previously disturbed now if your thumb penetrates more than two inches rather easily you have type C soil this is the least stable soil and generally consists of gravel lomi sand or soft clay with type C soil your excavation slope can be no less than six feet horizontal for every four feet vertical now that you know the proper slope to use for the various different soil types let's talk about shoring and shielding systems shoring and shielding are two different methods of protecting workers in a trench from a cave-in and can be used in conjunction with sloping shoring is a support provided to prevent the walls of a trench from caving in this is typically done using hydraulic pneumatic or timber braces the specific shoring setup that you use depends on the soil type and how deep your excavation will go shoring is always installed from the top down and removed from the bottom up so for example in a shoring system the stringers uprights and Uppercross braces would be installed first then the lower stringers and cross braces are put in the number of rows of stringers and cross braces depends on the depth of the excavation upper cross braces should be installed within two feet of ground level if the trench is up to eight feet deep two sets of stringers and cross braces are required in a trench eight to twelve feet deep three sets of stringers and cross braces is required and a 12 to 15-foot trench requires four sets of stringers and cross braces in looser soil conditions the uprights should be placed side by side plywood can be used in place of some of the uprights as long as the trench is less than nine feet deep the plywood is 3/4 of an inch thick or thicker the uprights are installed at no more than 24 inch centers and the cross braces do not bear directly onto the plywood but onto the stringers and uprights a shielding system on the other hand is designed less to prevent cave-ins and more to protect workers in the event of a cave-in and is typically done with the use of what's called a trench box or shield box trench box is typically come preassembled and are lowered into the excavation via machinery no workers should be present in the excavation when a trench box is being lowered or removed a standard trench box can be rented for about 150 to 200 dollars per day once in an excavation or trench a worker should remain aware of his or her surroundings as there are several hazards other than cabins that can be common in a trench the first of these is a hazardous atmosphere within the trench this can include flammable as well as toxic vapors flammable vapors with a vapor density greater than air can accumulate in low areas of a trench and ignite with any number of ignition sources sources of these flammable vapors can be ruptured pipes in the trench heavy vapors in the area and materials that are brought in toxic vapors can accumulate in trenches through the soil depending on the surrounding ground environments it's important to have testing equipment handy to make sure oxygen levels remain normal and toxicity levels remain low anytime oxygen levels dip below nineteen and a half percent respiratory equipment is needed another excavation hazard to be aware of is underground utilities like electric gas cable phone or water always call 8 1 1 or a similar one call underground service prior to excavation once in a trench a worker should always check for unknown utility lines that may have been damaged during the digging water accumulation can create a dangerous environment as well causing slip hazards electrocution and in the case of rain water accumulation even cave-ins from wet soft soil on the trench walls water pumps should be you in any trench where this happens maintaining proper access and egress to an excavation is important as well make sure that any ladder going into a trench extends 3 feet above that trench the precautions for working around excavations are fairly straightforward yet they remain one of the biggest sources of injury and death in all of construction that's why OSHA requires a competent person beyond every excavation job site to ensure the precautions we discussed here are followed to learn more about excavation safety or to get certified in a competent person course visit our website at each rain today comm thank you you

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14 thoughts on “Trenching and Excavation Safety

  1. the vid says that if oxygen content is bellow 19.5% respretory protection may be required. please be specific as this is misleading resperators do not add oxygen to air only filter certain toxins. they can not protect from oxygen difficency or displacement of oxygen in a trench or confined space!! please change this to be clear. miss leading information can potentialy be dangerious.
    also in my opinion best practise is to continiously ventilate from a good air source i to the trench not use ppe as ppe is a last line of defence and if at all possible not a first line of defence. i believe ppe should compliment a good health and safety control not be the sole control.
    To be clear i am passionate about health and safety this post is not ment to tear anyone down but simply to help correct a simple missunderstanding that could to an inexperianced worker could be dangerious.

    Derek L

  2. Check out 1:42 . . . you are supposed to have impalement caps on all bar, not just bump caps, also theres a cup on one of them 🙂

  3. In my class about project management I learn that Safety measure is your priority. Think safe. Your life is in your hand. You manage yourself, Don't let the work manage you. "Be Thinkers and not mirror reflectors of someone else thought"

  4. Trench work is dangerous, but it doesn't have to be as dangerous as some companies make it by failing to follow safety procedures.

  5. Due to the limited amount of time YouTube videos are allowed to take up, there can definitely be lot of information that gets left out – agree with you there, zzgergzz. An 8-10 minute video could never cover all of the "what if" scenarios, like the one you mention regarding Type A soil, that pertain to excavation safety. These videos are meant as a general overview and as such, cover the broader topic. Our complete safety courses on this topic go into much greater detail.

  6. Videos like these can be a valuable tool…The problem is that some things get left out. NO SOIL IS TYPE A if it is fissured or cracked or subject to vibration. Contractors can get in a lot of trouble classifying soil as type A. because they will not use shoring.

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