Excavations in Construction/Trenching
In the U.S., more than 800 construction workers
die every year while on the job.
One of the most dangerous types of construction work
is trenching, which kills, on average, 40 workers
Workers can suffer death or serious injury within
minutes of being caught in a trench cave-in.
But these deaths can be prevented.
The video you are about to see shows how quickly
cave-ins lead to workers' deaths.
The video will also show what employers must do
to assure that the work can be done more safely.
Employers have a responsibility to provide a safe
workplace and required protective equipment.
You'll see that using the right type of
protection saves lives.
Please be advised.
The scenes you are about to see deal with deaths at
construction sites and might be disturbing for some people.
All scenes are based on true stories.
Five workers were putting a sewer pipe into the
bottom of a trench, with a ladder nearby
to enter the trench.
There was nothing in place to protect the workers
inside the trench if the walls collapsed.
While the workers were inside the trench,
one side began to collapse.
Two workers were able to climb out using the ladder.
But the other three workers were buried in the soil.
And unfortunately suffocated to death
from the weight of the soil.
Let's look at the events leading up to this tragic
incident and see how it could've been prevented.
Employers must follow OSHA rules to protect
workers in trenches.
However, here, the employer did not follow OSHA's rules,
which led to these workers losing their lives.
Let's go over the main points of OSHA's rules
for trenches to see how to keep workers safe.
All trenches must follow OSHA's rules.
One cubic yard of soil can weigh as much as a car,
nearly 3,000 pounds, so unless the trench
is cut entirely into stable rock, protection against
cave-ins must be used for all trenches more than 5 feet
deep or for any trench that show signs of cave-in.
Before workers can do any work in a trench,
a competent person must conduct an inspection to
identify and remove any potential hazards.
A competent person is someone who can recognize hazards
in the area and who has authority to take quick
actions to eliminate the hazard, which may include
temporarily stopping the work.
Inspections must be performed at the start of every
shift, after a rainstorm, or whenever conditions change.
The competent person must also test the soil
in a trench.
OSHA requires at least one test by looking at the
soil and at least one test by hand.
If a person knows the soil types,
they can pick the right protective system to keep
workers safe when they're in trenches.
OSHA classifies soil in a trench as stable rock,
type A, type B, or type C soil.
Stable rock is the safest soil for a trench, type A
is the next most stable, and then type B, and
finally type C soil is the least stable.
It's important to remember that trenches can have
different types of soil based on depth and climate conditions.
The competent person can choose from different
protective systems for a trench, based on the types
of soil found.
For all trenches deeper than 5 feet deep or for
any trench that shows signs of cave-in, OSHA requires
sloping, benching, shoring, or shielding to protect
workers from cave-ins.
Let's review each of these different systems,
and then see how each one could be applied to
the cave-in incident shown earlier.
We'll look at sloping first.
Sloping protects workers by cutting back the sides of
the trench so the sides slant away from the trench.
OSHA's rules identify the degree of slope allowed
for each of the different soil types.
When trenches are less than 20 feet deep, these are
the basic maximum allowable slopes for each soil type.
Stable rock can be vertical walls, but can not be undercut.
For type A soil, OSHA requires that the walls be
sloped 9 inches out for every 1 foot of trench depth.
For type B soil, OSHA requires that the walls be
sloped 1 foot out for every 1 foot of trench depth.
For type C soil, OSHA requires that the walls be
sloped 18 inches out for every 1 foot of tren