08/1491 - MCU - Detached House [As Published] · 132008.1491

5 VALIDATION

Validation testing is regarded as an essential component of the management plan. Due to the variable
nature of mixing soil and fime, care must be exercise to obtain a representative sample for validation
analysis.

The engineer, project manager, geotechnical officer or other suitably qualified person must ensure the
validation testing has been performed and the results are satisfactory. A copy of the test certificates is to
be submitted to the local authority (or referral agency).

5.1 Validation Sampting

‘ The sub-samples must be representative of the treated soil volume. The location of the samples
should span the depth as well as the horizontal area for placed soil. For stockpiled soil the
samples should be evenly spaced through the soil mass.

The distribution of lime in a lime treated soil mass is typically highly variable on a small scale.
Whilst this mixing is adequate on a “landscape” scale it makes accurate sampling difficult. It can
be expected to collect some sub-samples with no lime and others with a high lime content. it is
necessary to collect a large number of sub-samples to form a composite sample that provides an
“average” lime content.

This process will take from one hour to one day per composite sample depending on the time
required for sub-sample extraction. If sampling is biased towards samples with a high lime content
the analysis results will be at odds with the known volume of lime that was applied.

Use a sampling device to obtain a minimum of 20 and up to 40 approximately equal volumes of
limed soil. The minimum sub-sample size should be in the range of 100-200 cc in volume. Mix
these carefully on a plastic sheet or container taking care to avoid segregation of the fine and
coarse fraction. Quarter down to retain a 200 gram composite sample.

* The location of the sample area/depth is to be recorded.
‘ Perform validation testing at the following rates:
* one test per 500 cubic metres for on-site placement
* one test per 250 cubic metres for off-site placement
. one test per 125 cubic metres for off-site placement within 50 metres of a drainage line,

stream or other surface water or where the watertabie is within 2 metres of the surface or
where the site is below the 50 year flood line.

Validation testing should include chemical analysis (GPOCAS or chromium reducibie sulphur test
suites) and calcium carbonate.

* It is recommended the sampling and mixing method is carefully documented and performed
according to plan. A proportion of samples will "fail". This is statistically predictable even though
the correct rate of time has been applied. Adherence to rigorous sampling and mixing techniques
makes it difficult to blame the sampling stage should a test fail.

* Samples are regarded as successfully treated provided they meet the following criteria:
a) oxidised pH >6.5
b) equivalent suiphur content below 0.03%
* In the event of a validation test failure a re-test is required. if the subsequent test fails then the

material must be re-timed to meet the test standard.

5.2 Scheduling of Validation Sampling

Validation testing of lime treated samples will require time for sampling, sample transport to a laboratory,
sample drying and analysis. This process can easily require 5-7 working days. Where soils are treated and
then placed the schedule of placement should allow sufficient time for the validation process. In the event
of sampies failing the validation test it will be necessary to add additional lime and re-test the treated
material again.

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