Page 30 - Trench and Excavation

Digging may not take place until an attempt at locating these installations is made unless an
inordinate time-period has passed since the time of request for location. This time-period is
somewhat dependent upon local custom, but a reasonable time-period (usually 24 to 48 hours)
should be granted prior to digging. If the time-period has passed and no location has been
established, digging may commence, but caution must be used. Contact is not necessary if the
work is to be done in a remote area where utilities are not likely, and no aboveground features
suggest utility presence. Once these installations are encountered and uncovered, they must be
protected, supported, or removed. Further, if soil removal near the installation is required, it should
be done by hand if possible.

Exposure To Vehicular Traffic And Barricading

If a worker is exposed to vehicular traffic on a public thoroughfare or construction site, he must
wear a reflective vest or some suitable, highly visible garment. This is true for workers who will be
on the top of the excavation all the time and for those who will be traversing the vehicle exposure
area.

The area around the excavation must be appropriately barricaded and protected while the
excavation is open. The barricades should be at least 6 feet away from the hazard. Please consult
the Construction Standard for Signs, Signals, and Barricades. It also must be backfilled as soon
as the work within the excavation has been completed. This is true for the primary excavation and
ancillary temporary excavations (temporary well, pit, shafts, etc.) as well.

Exposure to Falling Loads

One very dangerous component of the trenching operation is lifting, lowering, and dumping very
heavy material. The Competent Person has the responsibility of assuring that nothing is dropped
on a worker, whether in the trench or outside of the trench.

As the trench is being dug, large bucket-loads of soil or rock are being lifted and piled, either on
the ground or in a dump truck. Workers are not permitted to be close to the loads being lifted. The
exception is the dump truck operator. He is permitted to stay in his cab if it has the appropriate
protection.

If the spoil is to be stockpiled for backfill, the spoil pile toe may be no closer than 2 feet from the
edge of the trench. Not only does this prevent the soil from sliding back into the trench, but it also
decreases the surcharge load on the walls of the trench. If it is not possible to move the spoil pile
back, a retaining barricade must be installed to prevent the material from falling. Any scale or
loose clumps of material that are unstable on the face of the trench shall be removed. No worker
shall work above another worker on the sloped face of a trench. If crumbling of the sides cannot
be initially removed, a protective barrier will be placed between the scale and the workers.

Surface encumbrances are items that have the possibility of rolling into the trench and falling on
workers. Ideally, all construction materials and vehicles should be positioned as far away from
the trench wall as possible. Other non-mobile items such as large rocks should be immobilized
so they cannot roll into the trench.

If mobile equipment (such as a dump truck) is to be operated near the edge of the trench,
safeguards must be in place to assure that the vehicle does not enter the trench. If the driver does
not have a clear view of the edge of the trench, a spotter using hand signals barricades, stop logs,

Trench & Excavation
Competent Person Training P3 Safety Solutions LLC
Page 30