Attachment C - Soil Survey Report · MCU18/0013

Project No. 1-20119                                                                                                        Page | 6
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




          The site is well grassed and essentially free from larger vegetation. Several small
           shrubs are located along the southern easement and northern neighbouring property, as
           well as medium sized trees on the beach frontage at the eastern side of the lot (refer
           Plate E1, Appendix E).
          We understand that three now buried sheet pile walls exist on the site, installed in
           approx. 2006 (refer Section 1.6), installed as part of the construction of the neighbouring
           residence to the north (refer approx. location on drawing 1-20119-01).

The site plan (1-20119-01) in Appendix I, shows an overlay of the provided survey (refer
Section 1.6), as well as the proposed residence location.

    3.6 Geotechnical Model

           3.6.1       Subsurface Profile

Given access was only available for hand equipment due to the steep slope off the street, Hand
Augers and DCP tests were undertaken to provide an assessment of the competency of the
subsurface profile and to assess the likely depth to dense to very dense sands (i.e. DCP
refusal). Information from the adjacent investigation in 2004 was also utilized to confirm the
material types encountered. Therefore, the subsurface profile adopted from the testing program
is summarized below:-

          Fill – Encountered in hand augers to refusal depths (up to 0.7m in HA1) and described
           as Silty SAND (SM), very loose to medium dense.
          Sand - Assumed beneath the fill in all DCP tests to refusal depths and assessed as
           being very loose to very dense, with DCP refusal at 4.68m (HA1), 6.19m (HA2), 3.28m
           (DCP3) and 5.78m (DCP4).

Based upon our nearby investigation (No. 26) in 2004 (when access off the road for machinery
was possible), the deeper profile of the soils was assessed as:-

          Natural very loose to medium dense sands to depths of the order of 3.5m to 3.8m.
          Natural dense to very dense sands from ~3.5m to depths of the order of 12.0.
           These materials are also known as indurated sands or “coffee rock”.

A summary of the profiles encountered in the hand auger and DCP’s is included in Table 1 with
HA logs and DCP results in Appendix F and the test locations shown on Drawing No. 1-20119-
01a in Appendix I.