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Purpose
To determine whether
and how seepage measurements can be used to achieve the seepage management
objective.
Inputs
Seepage rate estimates, maps
from measurement techniques, management objectives.
Description
Evaluation of the results covers:
- Assessment of accuracy
- Comparison with expected results inferred
from site condition assessment of existing data (e.g. groundwater
monitoring data)
| Responsibility/decision
makers |
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This task is a combined project manager/officer level
task, with conclusions and recommendations reviewed
by management.
| Output |
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Outputs that can be obtained include:
- Assessment of whether management objectives have been
met
- Identification of priority locations for remediation
- Development
of work plans
- Planning of future directions
Local-scale recommendations
[Up to approximately 400m in length] |
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A local-scale investigation may suit an immediate purpose of
being seen to take some action at a particular
location and provide some site-specific management data. However, care
must be
taken in
extrapolating
from information obtained at specific
sites using techniques that
only provide spatially limited data (e.g.
point measurement).
An important part of the evaluation stage for local scale investigations
is assessment of whether the density of data (for point measurement
and groundwater bores) is sufficient to accurately define seepage
along
the section. Assessment of the accuracy of the results from point
measurement and groundwater bores will dependent on the variability in
the results. For a short section of channel it is presumed that
there will be minimal variation in channel and hydraulic properties
and therefore a reasonable degree of uniformity can be expected
in the results. [If within the section there is significant variability
(eg, in soil type or silt layer thickness) then evaluation will
need to allow for this]. Therefore there should be some assessment
of the uniformity of the results and some type of statistical analysis
is likely to be helpful here. Determining whether the results provide
a sufficient level of accuracy will require assessment compared
to the original objectives of the investigation. If the results
are deemed not sufficiently accurate, additional point measurement may
be required. If the results are deemed extremely unsuitable (eg,
seepage rate is not close to what is considered a reasonable number)
a new technique may need to be considered.
Intermediate to large-scale recommendations
[Hundreds of metres to tens of kilometres
in length] |
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The final aspect of seepage measurement and assessment
is to review the actual distribution
and rate of seepage measured
and inferred
from the tests at the various scales.
The review needs to determine
whether the management objectives
identified early in the project definition have been met. Project
review and evaluation
also
needs to take into account the need
for additional work
and refinement of the scale of testing
to achieve management targets.
Related pages
Previous: 5 Implement
seepage measurement techniques |
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