Part 3.1.1 Earthworks
Appropriate Performance Requirements
The provisions in Part 3.1.1 will enable earthworks associated with the construction of a building to be carried out safely and to avoid potential damage to the subject building, adjoining structures and property through the soil collapsing or subsiding. Exceptional site conditions (including the effects of torrential rain) may need special consideration and additional advice from appropriately qualified people should be considered.
State and Territory legislation may also have requirements that apply to earthworks, especially in relation to adjoining property and notification of owners of that property. Advice should be obtained from the appropriate authority before commencement of works.
The requirements of this Part are to be read in conjunction with Part 3.1.2 where an earth retaining structure is installed.
State and Territory Variations
State and Territory Variations
Except for Table 188.8.131.52 as refrenced by Figure 184.108.40.206 and except for Clause 220.127.116.11(a) for determination of a normal site as referenced by Clause 3.2.1, Part 3.1.1 does not apply in New South Wales.
Note: In New South Wales requirements for shoring and adequacy of excavation works are a prescribed condition of development consent. In addition consent authorities can place specific controls on siteworks associated with the construction of a building, by imposing further conditions of development consent. Information addressing siteworks can be found in the Department of Planning and Environment - Act and Regulation note "Health, safety and amenity during construction".
Acceptable Construction Practice
"Normal" site conditions relates to parameters such as—
- the site conditions not being significantly modified by the removal of previous buildings or other structures; and
- the moisture conditions on site being as a result of seasonal and climatic changes; and
- the site conditions not being subject to unusual moisture conditions caused by drains, dams, channels, ponds or tanks which are to be maintained or removed; and
- large trees have not been recently removed from the site in the area where the building is to be constructed; and
- other similar matters.
Further information regarding normal and abnormal site conditions can be found in AS 2870.
(see Part 3.2.4 for material description)
|Site cut (excavation)
slope ratio, angle of site cut
H:L Note 1)
slope ratio, angle
of batter H:L Note 1)
|Stable rock ( Class A)||8:1||3:3|
|Sand (Class A)||1:2||1:2|
|Firm clay (Class M-E)||1:1||1:2|
|Soft Clay (Class M-E)||2:3||Not suitable|
Notes to Table 18.104.22.168:
Figure 22.214.171.124a Site cut and fill using un-retained embankments - Site cut commencing at the allotment boundary or affecting an adjoining property
Figure 126.96.36.199b Site cut and fill using un-retained embankments - Fill commencing at the allotment boundary or affecting an adjoining property
Notes to Figure 188.8.131.52b:
- The angle for line A-A is defined as the maximum embankment slope ratio H:L in Table 184.108.40.206 and is taken from the bottom of the existing footing and is defined as the area suitable for excavation.
- Consideration must be given for drainage of surface water, particularly where fill affects an adjoining property.
220.127.116.11 Un-retained bulk earthworks - site cut
A site cut using an un-retained embankment must be—
within the allotment; and
not deeper than 2 m from the natural ground level at any point.
18.104.22.168 Un-retained bulk earthworks - fill
Fill, using an un-retained embankment must—
be placed within the allotment; and
be placed and mechanically compacted in layers not more than 150 mm; and
be not more than 2 m in height from the natural ground level at any point; and
where used to support footings or slabs, be placed and compacted in accordance with Part 3.2; and