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Geotechnical News June 2011
GEOTECHNICAL INSTRUMENTATION NEWS
be useful when trying to convince
decision-makers to accept this method.
Second Reason - Cost
Colleagues at Mueser Rutledge
Consulting Engineers in New York
discuss the issue from the viewpoint
of an instrumentation subcontractor
to the general construction contractor
(see
/
instrumentation_news.php and scroll
to
Geotechnical Instrumentation News,
Sept. 2009
). They warn:
The award of instrumentation work
based on the ‘bottom line’ includes
little consideration for quality, if
any at all … After the contract is
awarded to a construction contrac-
tor, potential instrumentation sub-
contractors are invited to re-bid,
so that the construction contractor
can compare line item breakdowns.
Instrumentation bidders revisit their
costs and strip contingencies. The
firm ultimately awarded the work is
likely to have assumed that the more
stringent specification requirements
will not be enforced.
In my own experience as an instru-
mentation subcontractor in USA, this
“stripping” can be up to 20%. Let’s look
at whether owners get a fair deal if this
happens. As an example, if the amount
assigned for field instrumentation ser-
vices in the construction contractor’s
bid is $800,000 the project owner pays
that amount, but only receives work
that costs $640,000. There’s a strong
message for owners there.
Third Reason – Adequacy of
Baseline Data
If construction work is likely to
impact on neighboring structures, and
monitoring with instrumentation is
required to mitigate the impact, there’s
another important reason for favoring
a contract directly with the project
owner. If field instrumentation services
are included in the general construction
contract, monitoring can’t start until
the award of that contract. In that case
there’s rarely sufficient time to establish
adequate records of pre-construction
behavior (baseline data). Structures
move and groundwater regimes often
change from season to season, and
monitoring data cannot be interpreted
correctly if adequate baseline data are
not obtained.
Fourth Reason – Greater Cost
and also Lack of Conformance
on Multi-general Contract
Projects
For multi-general contract projects,
there would be one monitoring
subcontractor for each construction
contract, hence greater cost when
compared with a single assignment.
For multi-general contract projects,
the various monitoring subcontractors
would probably make different selec-
tions of web-based data management
software, so that contract-to-contract
comparisons would be difficult. This
also places a heavier burden on a con-
struction manager needing to become
simultaneously proficient in more than
one system.
Recommendations for Assign-
ment of Tasks 1, 2 and 3 (Buy-
ing and Installing Instruments
and Collecting Data) when the
Monitoring Program has been
Initiated by the Designer of the
Project.
My recommendations are given in
Table 1.
Options for Assignment of Task
4 (Interpreting Data) when the
Monitoring Program has been
initiated by the Designer of the
Project
.
Clearly the people who initiated the
monitoring program should have a
role in interpreting the data. However,
the general construction contractor
MUST pursue a parallel effort, and
construction documents must specify
that the general construction contractor
has the
primary
responsibility for
interpretations and must stay on top of
the data flow at all times.
Closing Comments
I know very well that it isn’t easy to
convince owners (and project managers
in design firms, who supposedly have
the owner’s interests at heart) that it’s
in their interest to adopt the above
recommendations,
but it is!
Join the
campaign to ensure that the people
who have the greatest interest in the
monitoring and instrumentation data
should be given direct responsibility
for obtaining the data.
Join the campaign!
John Dunnicliff
Table 1. Recommendations for assignment of tasks 1, 2 and 3
when the monitoring program has been initiated by the designer
of the project
Type of Monitored Data Recommendations for Assignment of
Tasks 1, 2 and 3
Pre-construction baseline
data
Specialist firm under contract with the project
owner
Data during construction,
outside general construction
contractor’s work area
Specialist firm under contract with the project
owner
Data during construction,
within general construction
contractor’s work area
Either:
• Construction manager, with assistance from
general construction contractor for access as
necessary, or
• Specialist firm as assigned subcontractor, in-
strument suppliers as assigned suppliers (see
box on next page), or
• General construction contractor, with partner-
ing and rigorous
and
enforced
specifications.
