MCU14/0106 Appendix E - Engineering Report

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August 2004 -5- 04682104(AB)

 

Based upon our experience with similar subsurface conditions, we anticipate that ground water
seepage will probably develop at the interface between the near surface sandy soils and
underlying clays during periods of heavy or prolonged rainfall. Some seepage may also be
encountered from sandy or gravelly zones within the clay and sandstone strata. Considering the
topography of the site, we anticipate that the rates of ground water seepage will probably be
greatest around drainage lines and the low-lying southern area, particularly where the depth of
surficial sand increases up to about 1 m depth.

Sections A-A and B-B shows the subsurface conditions encountered in selected test pits and
boreholes.

5.3 Results of Geotechnical Laboratory Testing

Full laboratory reports for the geotechnical testing are presented in Appendix B together with a
summary Table B1. In summary:-

> Four single point CBR tests (four day soak) indicate a range of 7-16%, the lower and higher
parts of the range being representative of medium and low plasticity soils respectively.

> Eleven Atterberg tests generally confirm our visual classifications of soil type and plasticity.
When combined with the results of percent fines testing, the Atterberg results indicate that
the high plasticity silty clay soils have high a Shrink-Swell capacity.

> Two Shrink-Swell tests returned values of 2.9% (high plasticity sandy clay) and 3.3% (high
plasticity silty sandy clay), being in the moderate Shrink-Swell range. Four Shrink-Swell
tests were originally proposed, however two were replaced with Atterberg Limits and
percent fines testing due to difficulties encountered on site in attempting to recover
sufficient undisturbed (U50) tube samples.

> Six Emerson Class tests conducted on the range of clay soils encountered at the site all
returned values of six (ie. non-dispersive soil).

> Insitu soil density was estimated by measuring the soil weight and volume in four
undisturbed tube samples. Values of 1.92 and 1.96 t/m? were recorded for two high
plasticity sandy clay samples, whilst values of 2.03 and 2.12 t/m? were recorded for two
medium plasticity sandy clays.

Golder Associates