Page 69 - Trenchless Technology Piping Installation and Inspection

New Pipeline Installations 39

maximum drive length, and ability to handle different soil conditions
makes this method a practical and economical technique for install-
ing steel pipe casing. This method does not require any thrust block
as the ramming action impulses the pipe by the percussion tool. A
single size of pipe-ramming tool and the air compressor can be used
to install a wide variety of pipe lengths and sizes. Ramming tool can
be used for vertical pile driving, angular ramming, or pipe replace-
ment (bursting). It can also be used for assisting in HDD and MTBM
rescue operations.

Limitations
The major limitation of the pipe-ramming method is the minimal
amount of control over line and grade. Therefore, the initial setup is
of major importance. Also, in the case of obstructions, like boulders
or cobbles, especially for pipes with small diameter, the pipe may be
deflected. Therefore, sufficient information on the existing soil con-
ditions must be available to determine the proper size of casing to
be used. Other drawbacks include high noise levels that are typical
for pipe ramming (if no noise suppression is used). Unless special
push-on jointing system is used, the welding of two pipe sections
may take several hours. After completion of casing installation, the
product pipe is installed using spacers or other means (a two-phase
process).

1.9 Planning and Safety Considerations
Although trenchless installation methods significantly reduce the
negative impacts of open-cut trenching to quality of life and reduce
damage to pavements, and surrounding infrastructure, there are
some potential effects that should be understood. Many of the trench-
less methods described in this book may have several potential risks.
Some of these risks are common to several methods, while others
apply to a particular method. These potential risks should be consid-
ered in the planning, design, and preconstruction phase of the proj-
ect, and when deciding on a specific trenchless technology method.
Some risks can be reduced or mitigated by selection of experienced,
qualified contractors and trained/certified machine operators. While
generally jobsite safety is the responsibility of the contractors, project
owners and consulting/design engineers also have a responsibility
for ensuring proper method selection, and eliciting information on
safety and operational plans of the contractor by including require-
ments for submittals in the bid documents.
A safe job starts with a good planning and design, proper geo-
technical and site investigations, and decisions made during the
inception of the project, including the profile and alignment of the
installation. It is important that the owner and the engineer convey