Your Dam Your Responsibility (PDF~1.2MB)

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6 Safety Surveillance
6.2 Inspection Procedures and Methods
The procedure for dam safety surveillance is unique to each dam but consists essentially
of regular, close and systematic examination of the entire surface of the dam and its
immediate surroundings. Such procedures are already normal practice in the case of large
dams.
In the case of small dams, however, especially farm dams where owners have not
sought appropriate advice, there may be a perception that the above procedures are
unnecessary, or an unproductive use of time. There may also be a lack of knowledge of
what needs to be done. However, for small dams, surveillance programs can usually be
devised which are simple yet systematic and effective.
A safety surveillance inspection includes taking appropriate measurements and keeping
concise accurate records of observations made. Particular techniques and equipment
that might be used are outlined in Appendix A. For small dams it is prudent to obtain the
advice of a suitably qualified engineer to set up the program first, using a simple set of
pro-forma check sheets to record observations. They are just as sensible – in fact much
more so, given the potential for costs to you if it fails – as having your car checked and
serviced regularly, even though you do not think the car is about to give up on you yet!
These procedures form part of a dam safety management program and are intended to
catch problems early and enable action to be taken to prevent them developing further,
once detected.
6.3 Frequency of Inspections
The frequency of inspection required for an effective program of surveillance depends on
a variety of factors including:
(a) size or capacity of the dam;
(b) condition of the dam; and
(c) potential for damage resulting from failure of the dam (represented by the hazard
category).
Adoption of the inspection frequency for a particular dam is the responsibility of the
owner, though professional advice should be sought for large dams (ie. typically for dams
larger then 15 metres in height) or those suspected of being of a high risk or hazard
category. Suggested inspection frequencies are given in Table 6.1 but where licence
conditions require a surveillance program certified by a suitably qualified engineer the
frequency specified by the engineer shall be complied with.
As a guide, Table 6.1 gives suggested frequencies for a two-level surveillance program.
The higher level would comprise a full inspection using the relevant equipment and
techniques outlined in Appendix A. The second level is envisaged as a more frequent
quick visual inspection aimed at detection of unusual changes during the period between
thorough examinations.