Attachment C - Soil Survey Report · MCU18/0013

Project No. 1-20119                                                                                                        Page | 29
March, 2018
Ref: 1-20119, 2018-03-02, BR VER 2
Sam Hopper – Slope Stability Assessment and Geotechnical Report - Proposed Residence, 24 Arakon Crescent, Sunshine Beach




8.0 SOIL PERMEABILITY ASSESSMENT

    8.1 Introduction
This Section presents the results of the onsite testing carried out for the purpose of determining
the hydraulic conductivity of the subsurface soils in relation to the proposed stormwater
detention system.

All testing and the assessment has been carried out in accordance with AS 1547-2012 ‘On Site
Domestic Wastewater Management’.

    8.2 Field Testing
One field permeability test (HA P05) was carried out in approximately the requested location
(refer drawing 1-20119-01 in Appendix I).

The field test method employed in this investigation, i.e. Constant Head Test, was carried out in
accordance with AS 1547-2012, Appendix G.

At the test location, a 100mm diameter hand auger was drilled to a depth of 500mm. The test
hole was then filled to a depth of 350mm, the well permeameter was put in place and the test
commenced.

When the fall became constant, i.e. 10% or less change between successive readings, or flow
ceased, the test was completed. Readings were taken initially 30 second intervals to 10
minutes, then at one minute intervals to 15 minutes. Test results are included in Appendix K.

The subsurface conditions encountered at the test locations comprised silty sand fill to the total
depth of the hand auger, likely overlying natural very loose to loose silty sand. Refer attached
hand auger logs in Appendix F.

    8.3 Textural Method
In addition to the Constant Head Tests, the permeability was also assessed from the textural
classification of the soils within the land application area. This method is in accordance with
AS1547-2012 (Table 5.1 ‘Determination of Soil Category’) and can be used where the field
testing may not provide representative permeability values, e.g. test may overestimate
permeability in sands and may not be a practical test for low permeability clays.

The soil types at this site expected to form the bulk of the disposal field are based on Table 5.1,
which provides representative permeabilities, based on the Soil Category:-

          Soil Texture                                   = Gravels & sands to sandy loams
          Soil Category                                  = 1 to 2
          Permeability (ksat), (m/d)                     = 1.4 to >3.0

    8.4 Conclusion
          The soil type in the area of the proposed stormwater detention tank system consists of
           gravels and sands and sandy loams - Soil Category 1 to 2.
          In situ permeability test results recorded saturated hydraulic conductivity values (k sat) of
           0.6m/day.