Protect Yourself on Excavation Sites
Protect Yourself on
Excavation Sites
1. OSHA requires a
competent person to be on-site when doing excavations. That person must be able
to recognize hazards that exist and hazards that could occur, and that person
must have the authority to take action to correct those conditions. S/he must
also inspect the excavation, the surrounding areas, and the protective systems
every day before the start of work.
2. For all
excavations and trenches deeper than 5 feet, but less than 20 feet deep, you
must use one of three methods:
a. Sloping or
benching. Sloping involves cutting back the sides of the trench to a safe angle,
so it won’t collapse. Benching is a variation that adds a series of benches
(steps) that also approximate the safe sloping angle. The angle that you use
for sloping depends on the soil type. Soil types are: Solid rock, Type A, Type B and Type C (which
is the least stable). However, using a cutback slope of 1-1/2 feet horizontal
to 1 foot vertical is a safe sloping angle for all soil types. Note: Type C
soil can only be sloped: it’s too unstable to be benched.
b. Trench box or
shield: Although these are NOT designed to prevent cave-ins, they should protect
workers within the structure if a cave-in occurs.
c. Shoring:
These
are structures built of timber, or they can be mechanical or hydraulic systems,
that support the sides of an excavation. Sheeting is a type of shoring that
keeps the earth in place.
3. With shoring and
shielding, workers are only protected as long as they stay within the confines of
the system.
Safe Electrical Safety Practices
4. If the competent
person sees signs of a possible cave-in, even at depths less than 5 feet, one
of the protective systems must be used.
5. If the excavation
is more than 20 feet deep, a professional engineer must design the system to protect
the workers.
6. A ladder,
stairway or properly designed ramp is required in any trench 4 feet or deeper
at least every 25 lineal feet of the trench. It’s best to have one at each end
of an excavation.
7. A competent
person must determine the type of soil (Solid Rock, Type A, Type B, Type C) by
using at least one visual and one manual test. This must be done before anyone
enters the excavation.
8. Hazardous
atmospheres can sometimes be a danger in excavations. Air Testing is done in
the following order, and hazards can include:
● Oxygen-deficient
atmospheres can asphyxiate (suffocate) you. You need at least 19.5 percent oxygen.
Normal level is 20.9 percent.
● Flammable gases or
vapors, that reach a certain concentration known as their Lower Explosive Limit
(LEL), can lead to fires and explosions. In Excavations, you can’t exceed 20
percent of the LEL. (In Confined Spaces – a different standard – it’s 10 percent
of LEL.)
● Toxic gases or
vapors can poison you, leading to death or serious health problems. Don’t exceed
Permissible Exposure Limits (PELs).
9. Remember: CALL BEFORE YOU DIG.
Call to contact your local one-call service several days
before you dig, to locate and mark with proper color codes all underground
utilities. These could be: electrical, gas, water, sewer, steam, chemical and
telecommunications. You must take additional precautions when reaching marked
locations.
10. BEWARE – SOIL IS VERY HEAVY!
Some types of
soil can weigh around 3,000 pounds (that’s 1.5 tons!) for every cubic yard.
Don’t take chances – make sure a competent person has put a protective system
in place before you start work.
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