Attachment C - Soil Survey Report · MCU18/0013

Project No. 1-20119                                                                                                        Page | 20
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




           7.2.3       Further Comments Regarding Foundations

Foundation Design

As noted above this site has been classified as ‘P’, however, if the site was classified based on
reactivity alone, under normal moisture conditions, a ground surface movement (ys) of <20mm
(maximum) could be adopted, which relates to a Class ‘S’ (slightly reactive) site (considering
the proposed development, existing subsurface profile as per boreholes records, and taking into
account other relevant geotechnical data held by Soil Surveys Engineering).

It should also be noted that the methodology adopted for determination of the site classification
assumes the structure has performance requirements similar to domestic type construction.

Development of Abnormal Soil Conditions

It is recommended that design works for the proposed development take into account the long
term effect of any design elements on the subsurface moisture conditions under and around the
structure.

These design works should consider aspects of the design that may contribute to the
development of abnormal moisture conditions i.e.:-

          Site drainage
          Gardens and landscaping
          Future planting of trees and shrubs
          Services and repair of leaks

The designer is directed to AS 2870-2011 Appendix B and Section 8.2.7 of this report which
outlines measures that should be considered.

           7.2.4       High Level Footings

Where high level footings are adopted, our recommendation is that all perimeter footings,
footings under isolated columns and strip footings below internal load bearing walls be founded
at least 300mm below platform level and a minimum of 300mm into the natural sands.

Table 6 outlines minimum allowable bearing capacities for high level foundations on the site.

 TABLE 6             ALLOWABLE BEARING CAPACITIES FOR HIGH LEVEL FOOTINGS
                                                                                             Allowable Bearing Capacity (kPa)
                                     Material
                                                                                             Strip Footing       Pad Footing
 Fill                      Uncontrolled                                                          NR                 NR
 Sand                      Loose                                                                 NR                 NR
                           Compacted to 70% density index                                        100                125
                           Medium Dense                                                          100                125
                           Dense                                                                 200                250
                           Very Dense                                                            400                450
 Note: NR - Not Recommended

The base of all pad and strip footings founding in sand should be individually re-compacted
using a vibrating plate compactor prior to placement of reinforcing steel and concrete as soils
may be loosened during the excavation process by machinery action.