Figure 8-10.Types of interlocking sheet piles.
underground installations in the area including sewer,
water, fuel, and electrical lines. A Builder must also
take precautions NOT to disturb or damage any utility
while digging and to provide adequate protection after
any such exposed. Make sure you have a digging permit
on the jobsite and that you follow its guidelines.
Many safety codes also require that the excavation
be inspected by a qualified person (ROICC or safety
officer) after a rainstorm or any other hazardous natural
occurrence. Avert earth bank cave-ins or landslides by
increasing the amount of shoring and other means of
Provide convenient and safe access to excavated
areas for your crew. Such access may consist of
stairways, ladders, or securely fastened ramps.
During excavation some soil types pose greater
problems than others. Sandy soil is always considered
dangerous even when it is allowed to stand for a period
of time after a vertical cut. The instability can be caused
by moisture changes in the surrounding air or changes
in the water table. Vibration from blasting, traffic
movement, and material loads near the cut can also
cause earth to collapse in sandy soil.
Clay soils present less risk than sand; however, soft
clay can also be dangerous. You can do a simple test of
clay conditions by pushing a 2 by 4 into the soil. If the
2 by 4 is easily pushed in the ground, it indicates that
the clay is soft and may collapse. Silty soils (a
combination of sand and clay) are also unreliable and
require the same precautions as sand.
When there is sufficient space around the
construction site, slope the earth banks as necessary to
prevent collapse. The Occupational Safety and Health
Administration (OSHA) code regulations for the
construction industry recommends a 45-degree slope
for excavations with average soil conditions. Solid
rock, shale, or cemented sand and gravel may require
less slope. Compacted sharp sand or well-rounded
loose sand may require more than a 45-degree slope.
SHORING VERTICAL WALLS
Shoring (supporting) the vertical walls of an ex-
cavation is required when sloping is considered unsafe
or inadequate. Soil types, such as clays, silts, loams, or
non-homogenous soils, usually require shoring.
Shoring may also be required where there is insufficient
room for sloped banks. This is particularly true in
industrial and commercial areas where new construc-
tion is right next to existing buildings. In addition to
preventing injury from collapse of excavation banks,
stability of the foundation walls of adjoining buildings
must be protected. Shoring for high vertical walls is
supervised by a civil engineer, and the installation is
supervised by qualified personnel. Do not remove the
shoring system until the construction in the excavated
area is completed and all the necessary steps are taken
to safeguard workers. Two methods commonly used
to shore high vertical excavation banks are the use
of interlocking sheetpiling, as shown in figure 8-10