Page 179 - Moving the Earth_ The Workbook of Excavation

BASEMENTS

BASEMENTS 4.19

FIGURE 4.18 Multiple-basement cut.

Use of part of the spoil for raising the ground level decreases the depth of digging necessary.
Another method of line digging is to load most of the spoil into trucks, sell or dispose of part
of it, and save only as much as is necessary for backfilling spaces between other houses in the
same development.
A third method is to haul away all the spoil for use elsewhere, and obtain backfill by dozer cut-
ting on the uphill side of the houses.
It is also possible to dig such a trench with dozers, working across it and piling soil on one or
both sides. Or scrapers, working the long way of the cut, can haul to any desired location.
The first method requires at least partial backfilling as soon as the foundations are up, to pro-
vide access to building material. The weight of the fill and of the large dozers commonly used is
likely to break in uncured foundations, particularly if they are not braced by first-floor beams.
A large dragline might be able to pile all the spoil on one side to allow access to the other.
The other methods give immediate access to the front and back, and allow space for piling
materials. Backfilling can be postponed until the building is completed.
Relative cost will depend partly on the value of the spoil removed.

CONTRACTOR’S SETUP

A contractor setup to do basement excavations, one at a time, will probably have a combination
of equipment including a backhoe, a small bulldozer, and possibly a dump truck for hauling the
spoil material away. The backhoe does the digging, and the dozer moves the material that may be
needed for backfill out of the way for the backhoe and then is available for backfilling, when that
is to be done. If there is excess material to be hauled away, the fact that the contractor has a dump
truck for that purpose means that the owner, or building contractor, does not have to get another
subcontractor to do that part of the job. A contractor who does a lot of basement excavations, for
either residential or commercial construction, will probably have a fleet of backhoes of various
sizes for the variety of excavations to be done, small and large dozers, and various sizes of dump
trucks. The fleet may not be large enough to warrant having repair facilities. Instead, the contractor