07/1586 - Response to Information Request [As Published] · 132007.1586

* Project No. 307-2624 Page 3
August, 2007

 

. State Planning Policy 2/02 Guideline Planning and Managing Development

Involving Acid Sulfate Soils

The detailed borehole record sheets are included in the Appendix A.

4.2. Subsurface Conditions

5.0

The subsurface profile encounted by the boreholes consisted of a surface layer of
gravelly sand or silty sand fill overlying natural silty sand.

The surface layer of silty sand fill is described in the borehole logs as fine to coarse
grained, mostly grey or grey brown, and with little or no fines and a trace of organics in
some parts. The layer of silty sand fill extended from the surface to 0.6 - 0.7m depth in
the boreholes.

The natural sand encountered below the surface fill, is inferred to be alluvial and is
described in the logs as fine to medium grained, and mostly pale grey with some bands
of dark grey.

LABORATORY TESTING

Two stages of laboratory testing were undertaken for this project.

5.1 Preliminary Screening Tests

The first stage consisted of the initial qualitative screening of the disturbed samples,
conducted using the field pH (pHr) and oxidised (pHrox) test method, and this was
carried out by Soil & Water Laboratories (SWL), on each of the disturbed samples. This
is a quick, qualitative assessment of the potential acidity of the soil. The results of these
screening tests were used to select which of the soil samples should be further
assessed by quantitative laboratory testing.

Laboratory test results for the pH- / pHrox screening are presented in Appendix B, and
the measured values in the this screening (23 No. sets in total) were seen to vary within

the following ranges.

¢  pHr 5.8 to 6.6 (mean value = 6.2)
© pHeox 3.3 to 5.0 (mean value = 4.1)
¢  pHr-pHrox 1.4 to 3.3 (mean value = 2.1)

 

F SOIL SURVEYS ENGINEERING