UFC 3-220-01N
15 AUGUST 2005
can be easily followed and their adequacy checked. The first principle of
excavation stabilization, using shoring and bracing, is that the placing of supports
should proceed with excavation. The excavation cut should not be allowed to
yield prior to placing of shoring and bracing since the lateral pressures to be
supported would generally be considerably greater after yield of the unshored cut
face than if no movement had occurred prior to placement of the shoring.
Excavation support systems are discussed in paragraph 8-1. All safety
requirements for shoring and bracing as contained therein and should be strictly
enforced.
The inspector must be familiar with stockpiling requirements regarding the
distance from the crest of the excavation at which stockpiles can be established
and heavy equipment operated without endangering the stability of the
excavation slopes. He must also know the maximum height of stockpile or
weight of equipment that can be allowed at this distance.
Excessive erosion of the excavation slopes must not be permitted. In areas
subject to heavy rainfall, it may be necessary to protect excavation slopes with
polyethylene sheeting, straw, silt fences, or by other means to prevent erosion.
Excavation slopes for large projects that will be exposed for several seasons
should be vegetated and maintained to prevent erosion.
8-4.1.2.4
Stockpiling Excavated Material. Generally, procedures for stockpiling are left
to the discretion of the contractor. Prior to construction, the contractor must submit his plans
for stockpiling to the contracting officer for approval. In certain cases, such as where there are
different contractors for the excavation and the backfill phases, it may be necessary to include
the details for stockpiling operations in the specifications. In either case, it is important that the
stockpiling procedures be conducive to the most advantageous use of the excavated
materials.
As the materials are excavated, they should be separated into classes of backfill
and stockpiled accordingly. Thus the inspection personnel controlling the excavation should
be qualified to classify the material and should be thoroughly familiar with backfill
requirements. Also, as the materials are placed in stockpiles, water should be added or the
materials should be aerated as required to approximate optimum water content for
compaction. Field laboratory personnel can assist in determining the extent to which this is
necessary. The requirements of shaping the stockpile to drain and sealing it against the
entrance of undesirable water by rolling with spreading equipment or covering with
polyethylene sheeting should be enforced. This step is particularly important for cohesive soils
that exhibit poor draining characteristics and tend to remain wet if once saturated by rains.
Stockpiles must be located over an area that is large enough to permit processing and where
they will not interfere with peripheral drainage around the excavation and will not overload the
slopes of the excavation.
In cases where significant energy and cost saving can be realized, special
stockpiling requirements should be implemented. An example would be a large project
8-65
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