Att 9 - Geotech and PASS report

                                                                                                           Page 7 of 13




Temporary and long term batter slopes may be undertaken using the suggested batter slopes
provided in Table 3. Where groundwater seepage is encountered, batter slopes will need to be
considerably flatter.

Table 3: Batter Slopes
                                                                         Safe Batter Slope (H:V)
                      Material
                                                              Short Term                       Long Term
 Engineered filling*                                               1:1                              2:1
 Dry medium dense sands                                           1.5:1                             2:1
Notes:    * Depends on filling material type and level of compaction. Assumes clayey material compacted under ‘Level 1’
         inspection and testing.


Slopes may need to be flattened to 3H:1V or less, in order to allow vehicle access for maintenance of
the slopes. It is recommended that all batters incorporate crest and toe drainage. The batters should
also be covered with topsoil and vegetation to provide long term erosion protection.



8.4      Site Classification

Site classification of foundation soil reactivity strictly only applies to residential buildings up to two-
storeys and to other buildings of similar size, loading and flexibility as defined in accordance with
AS2870. Such classification; however, provides an indication of the propensity of the ground surface
to move with seasonal variation in moisture content, and can be used to assist in the design of brittle
elements in non-residential buildings.

In strict accordance with AS 2870, given the presence of filling and soft soils at depth in some of the
bores, this site would be classified as ‘Class P’ (problem site) requiring design by engineering
principles.

Based on the subsurface conditions encountered and the results of laboratory testing, shrink-swell
movements are estimated to be less than 20 mm. It is noted that the shrink-swell movements and site
classification will be affected by the proposed earthworks. The use of clay filling will increase
estimated shrink-swell movements, in particular imported high plasticity clay. It is preferable if imported
filling comprises low plasticity granular fill.

Site movements will also include site settlements, which are in addition to shrink-swell movements;
these settlements are discussed below. The total estimated site movements are estimated to be in the
order of 40 mm to 50 mm, consistent with Class H1 conditions.



8.5      Site Settlements

Preliminary estimates of settlement were made using DP’s in-house software T-REX with soil
settlement parameters assessed using published correlations and local experience.




Geotechnical Investigation, Proposed Commercial Development                                        90151.00.R.001.docx
11-19 Hilton Terrace, Tewantin                                                                               May 2017