40 Point Explanation
Steps
to secure trench walls are required when the trench is 4 feet deep or
deeper. If the trench is over 20 feet deep, the protective system must
either be approved in manufacturer’s tabulated data or designed by a
registered professional engineer.
Sloping the trench walls helps to stabilize them.
Shoring the walls keeps them from collapsing.
Shielding workers inside protective structures inside the trench is also
acceptable.
What is NOT acceptable is NO protection for the workers.