Appendix D Geotechnical report · MCU18/0013

Project No. 304-2014
November, 2004 Page 6

 

The subgrade should be proof rolled (where appropriate) under the supervision of
Soil Surveys Engineering using a vehicle with a tare of at least 5 tonnes and then
compacted to the required degree. In areas of cut, proof rolling may be deferred
until after the cut operation. Areas demonstrating excessive movement should be
treated (dried and recompacted) or removed and replaced with compacted fill.
Treatment should be to a standard sufficient so that the subgrade passes proof

rolling and that compaction can be achieved in the first layer of fill.

6.2.3 Fill Material

While it is noted that significant filling is not anticipated, backfilling around the proposed

in-ground water tank should be carried out in accordance with AS.3798-1996, and the

following should be noted:

The insitu soils, where free of organic and deleterious material, may be used for
structural fill provided the moisture content of the soils on placement approximates
the optimum moisture content required for compaction. This may require
conditioning to bring the soils to optimum.

Any imported fill, if needed to make up earthwork deficiencies, should have a soaked
CBR of not less than 10 percent and a maximum aggregate size of not greater than

75mm with not more than 20% greater than 20mm.

6.2.4 Compaction Standards

Guidelines for minimum relative compaction values for insitu soils and imported fill for the

building and pavements are presented in Table 2.

 

 

 

TABLE 2 COMPACTION RECOMMENDATIONS
Location Minimum Density Index
Building Area 70

 

 

 

 

* Field density testing should be carried out to check the standard of compaction

achieved and the placement moisture content. The frequency and extent of testing
should be as per guidelines in AS.3798-1996, Section 8.0.

Backfilling for service trenches etc. should use good quality material free of organic
and deleterious matter, either select fill won from site or imported fill. The backfill
should be placed in uniform layers over the full width of the excavations with the
layers not exceeding 200mm thickness, loosely placed. The backfill material should
be compacted to the specifications outlined above for insitu or imported cohesive

material.

 

# SOW SURVEYS ENGINEERING