Page 180 - Moving the Earth_ The Workbook of Excavation

BASEMENTS

4.20 THE WORK

can have extended warranties from the dealers of the equipment, so that they service the equip-
ment as needed. Paying for the dealer’s service department is probably going to be more eco-
nomical than hiring a full-time mechanic and setting up one’s own repair facility.

HAULAWAY DIGGING

Trucking Spoil. In large commercial excavations of the haulaway type, one of the most impor-
tant considerations is arranging for the disposal of the spoil, except when it is to be used as fill on
the same project. It may be possible to sell it profitably, or it might be necessary to pay someone
for the privilege of dumping it.
Disposal arrangements may not only determine the price to be charged for the digging, but also
the time of starting the work, and the number and type of excavating and hauling units to be used.
The distance to the dump may be much farther for the trucks than for a car because of restric-
tions on trucking on residential streets. An inspection should be made of the dumping site, and
any price quoted for fill should contain provision for additional charges for dumping delays.

Permits. An excavation contract should specify that the owner, or general contractor, is respon-
sible for obtaining all permits necessary for the work. If the job is stopped because of failure to
have such permits in order, the excavator should have the privilege of charging for the tied-up
equipment on an hourly basis.

Machinery. In a medium to large excavation, a crawler front-end loader, a backhoe, or a front
shovel unit is usually preferred, unless the bottom is too wet or sandy for trucks. The backhoe
needs less space, does not tear up the floor, is better in rock, and can tolerate rough or steep footing.
Increasing size and decreasing depth favor the loader. It can replace the shovel on most jobs.
A hydraulic backhoe of sufficient size does the neatest work. If the bottom is bad, it can load
on top, but production is greatest with haulers below it.

Ramps. In most cases, the power backhoe or front shovel cuts a ramp down, inside the digging
lines, which must be of such grade and material that loaded trucks can climb it. The grade may be
between 1 on 5 and 1 on 12, depending on the power of the trucks and the loads placed on them.
The slope is made as gentle as the length and depth of the hole permit, for larger loads and fewer
breakdowns.
If the plot is sloped, the ramp should be cut in from the lowest point on the edge to which trucks
have access.
Earth ramps are generally removed immediately upon completion of the excavation they ser-
viced. It is usually necessary to bring in a backhoe or a clamshell for this job, as the yardage is
too great for hand labor.
Timber ramps afford less tractive resistance and better footing than earth, and so can be built
with a steeper slope. They can be left in place during construction of the foundation for conve-
nience in moving building material. However, timber work is so expensive that these ramps are
largely limited to use in excavations that are very deep in proportion to their size.
Pit Floors. The shovel may dig the floor of the pit exactly to grade, or may dig portions of it
below grade, to allow room for disposal of spoil from hand-dug trenches or removal of the ramp.

EXAMPLE

Figures 4.19 and 4.20 show a basement layout for a business building. The excavation is to be 90
by 120 feet for an 88-foot by 116-foot building, 18 feet deep in firm clayey material, in a level
plot measuring 100 feet by 200 feet. The structure will be against the sidewalk line, 17 feet back