Response to Information Request - Received on 19/04/2012 · OPW11/0335

5.0        SOILS INFORMATION


Soils testing undertaken by Butler Partners (2007)involved six (6)bores drilled to depths of 2.5
meters from across the site.                Surface soils were described as fill (silty sand with sub-angular
gravel)     over     most of the development (particularly the lower slopes), with                                         some        silty sand
observed near the eastern margin. The depth of surface fill was 0.8m on the lowest slopes, and
was about 0.2m further            upslope.

Soil under the surface fill was described as dark grey-brown silty clay or silty sand on the lowest
slopes (under the thick layer of surface fill), or light grey-grown fine sand under the 0.2m of fill
further upslope. The soil texture described by these tests were used to assess the soil erosion
hazard for the SECP by an Erosion Hazard Assessment Form (Queensland Best Practice
Environmental Management Guidelines 2009).


Butler and Partners (2007)identified acid sulphate soils at isolated locations, which will require
management and treatment to neutralise any net acidity if the soils are disturbed. The affected
soils are the dark grey-brown silty clay under the 0.8 m of fill adjacent to the wetland heath on
the western  margin of the development site. Butler and Partners developed a draft Acid
Sulphate Soil Management Plan (appended in Butler and Partner, 2007). This report has been
included as Appendix G of this document. Any soil disturbance in the indentified area is to be
managed in accordance with the Butler & Partners ASS Management Plan.

The SECP does not propose the installation of sediment ponds to collect runoff from the
building site to avoid disturbing acid sulph te soil. Instead sediment fences have been
recommended, with filter socks at outlet points to remove suspended fine sediment from the
                                                          ’ ,



overflow (Appendix D).


The Bioretention trenches to be installed ..,as part of the SMP are indented to be installed
primarily into the fill layer being applied to the,area, with minimal further excavation to a depth of
2.5mRL being expected to accommodate the           ;gravel layer. The Butler & Partners report (2007)
indicates that potential acid sulphate soils ex_ist at, a depth of approximately 2.3mRL under the
area of the site intended to situate the /Bioretention Trenches.             While the likelihood of
disturbance of Acid Sulphate Soils is minimal; an Acid Sulphate Soil Management Plan
(ASSMP)has been developed, by Butler & Partners and is inCluded in the report in Appendix G.
                                                                                         Ii:




Soil tests were also undertaken    by Simmonds and Bristow on the 10th July 2009. Eleven
samples of surface soils (0 100 mm) were collected across the site area, from the road to the
                                        -




edge of the field (refer to sample location map in Appendix B). The soils were analysed for
Loss on Ignition, Total Nitrogen, Total Phosphorus, pH, and Electrical Conductivity (Table 5-1).
These soils were slightly to strongly acidic, which lessens the availability of soil nutrients
available to plants. The soils had inherently low total nitrogen concentrations, and very low soil
salinity, based on these data.

Table 5-1: The Quality of Surface Soil Measured in the Undeveloped Site

                 ,
                     Soil Quality Indicator                                    SS2       SS3              SS4        SS5       SS6         SS7

Conductivity (1:5 soil: water extract) ()lS/cm)                                 76             23           26        19          32        29

Loss on Ignition at 4500C (%)                                                   2.4        1.6             1.6       1.7       3.7          2.2

pH (1:5 soil: water extract)                                                    6.6        5.6             5.4       5.4       5.6          5.5

Total Nitrogen as N (mg/kg)                                                   4700       3600             3600      6900      5700         4200

Total Phosphorus as P (mg/kg)                                                  1000      1100              580      1100       710          700




@2012 Simmonds & Bristow Pty LId                                Contrast Constructions                               J-1005-310   -
                                                                                                                                      22 March 2012
1:ICLlENTFILESIContrast Constructionsl1108-155c   -
                                                      Essence of Peregian SCEP Stage 1 Updatel09    _
                                                                                                        Output Documentsl11 08-155C SWMP
                                                                                                                                  _




SCEMP_Scanlon Property Group_V4 O_ta_120321 ,doc                                                                                       Page 6 of 24