01 July 1997
FACTORS FOR DESIGN AND CONSTRUCTION
2-1. EQUIPMENT SELECTION. This chapter describes the criteria by which pile driving equipment is
a. Commercial Factors. The Government may use either Government-owned equipment or rent pile
driving equipment from a commercial source. First consideration should be given to the use of Government-
owned equipment, and a thorough search should be carried out to ascertain if such equipment is available.
If suitable equipment cannot be located as a result of this investigation, then select rental equipment on the
basis of the other criteria in this chapter.
(1) Proximity and Availability. The importance of using readily available equipment cannot be
overemphasized. Unless the requirements of the foundation dictate otherwise, equipment selected should
be in reasonable proximity to the job site, available from more than one source, and in time for construction.
(2) Size of equipment. Larger equipment is generally less available than smaller equipment. Use
of large equipment that is not readily available will result in delays and, with rental equipment and higher
rental rates, will add to the cost of the job.
b. Noise. The entire matter of allowable noise disturbance is subjective and should be carefully
evaluated before seeking special methods to reduce its effect. Pile driving can generate high noise levels.
In many cases, proper explanation of needs, development of alternative methods and job site arrangements,
and/or judicious selection of hours of operation can eliminate confrontation.
(1) Noise from Impact Hammers. Impact hammers produce the highest sound pressure levels.
There are two primary types of noise which are produced by an impact hammer. The first is impact noise
produced by the ram striking the pile. The second type of noise is produced by the operating steam, air, or
diesel exhaust as it is exhausted from the cylinder. (This is not present with hydraulic impact hammers.)
(a) Impact Noise. Cushion material can be used to reduce the noise levels as well as modify
the impulse duration as required by soil type and piling composition. Also, when driving steel piles, a canvas
hood should be provided to reduce noise.
(b) Hammer Exhaust Noise. The exhaust noise can also be reduced through the use of an
exhaust muffler. Any device attached to the hammer must be secured properly to prevent it from being
jarred loose during driving.
(2) Other Equipment Types. Preboring and the use of vibratory hammers may produce lower
sound pressure levels, but may not be less disturbing than the use of an impact hammer. This depends
upon the interaction of the pile and the soil, and whether the hammer and pile resonate in a fashion that
produces high noise levels. Where noise must be completely eliminated, jacking and screwing methods are
likely to provide the least disturbance.
c. Effects of Vibration. The vibration due to pile driving shall be considered concerning possible
damage to adjacent construction. Damage due to vibration is a function of both amplitude and frequency. If
there are adjacent structures susceptible to vibration damage, then preliminary investigations should be
conducted and vibration monitoring should be done during pile load tests and actual driving if necessary.
(1) Impact Hammers. With impact hammers, this might indicate use of a smaller hammer or a
double acting hammer as opposed to a single acting model.