Page 414 - Trenchless Technology Piping Installation and Inspection
P. 414
364 Cha pte r Ni ne
There is no single best way to conduct a construction activity. Per-
formance of a work task depends on variables related to the work,
such as the type of pipeline and utility application, type and diameter
of pipe, the location of the project, the work hazards, the various con-
tractual and legal constraints, and so on.
Early planning will provide more time to carefully consider the
impacts of all project constraints and to devise efficient strategies for
dealing with project requirements. For planning purposes, tasks
should be divided into smaller independent executable subtasks.
This enables project engineers to structure unwieldy and complex
problems into smaller digestible tasks. The more time and resources
allocated for planning at each stage of project, the greater the oppor-
tunity to develop optimal solutions rather than something that is
“bare minimum.”
In planning trenchless projects it is necessary to give considerable
attention to safety. Engineers have both a moral and a legal responsi-
bility to the public, to construction workers, and to the end-users of
the projects to ensure that the workplaces, construction operations,
and the work environment are safe. The machines that are used in
trenchless installations can be very sophisticated, but they can also
present a variety of hazards such as those associated with open-cut
construction. Safety planning will identify hazards and develop ways
to protect both the construction workers and the public.
All equipment operations entail risk. The level of safety planning
that is needed should be based on the specific risks associated with
work conditions. When risks are identified in advance, and steps are
taken to control, reduce, or remove them, links are being removed
from the chain of potential errors. Experience has shown that acci-
dents are usually caused by a chain action of errors.
When the engineer prepares a plan and cost estimate for a trench-
less project, the decision process is often not a list of sequential activ-
ities. The process takes the form of recurrent activities with feedback.
As decisions are proposed, further investigation and collection of
more information is usually necessary to reduce uncertainty.
Contractors have a right to rely on owner-provided information.
Additionally, many contracts will contain a differing site condition clause.
Material differences in conditions are applicable in either of two cases.
A type I differing site condition exists when actual conditions differ
materially from those “indicated in the contract.” A type II differing site
condition arises when actual conditions differ from reasonable expec-
tations. These clauses provide the constructor some protection from
geotechnical risks. They do not, however, eliminate the contractor’s respon-
sibility for performing a thorough examination of project conditions.
Field investigations, geologic and soil studies, and analysis of
meteorological data, enable the contractor to better quantify what has
been presented in the bid documents. The contract documents will
usually include geotechnical data and information that was gathered