CS-16.4 Subgrade Preparation

1. The exposed subgrade forming the kerb and channel bed shall be compacted to refusal with a plate compactor or similar compaction device. In this section "compacted to refusal" is deemed to mean when the plate compactor ceases to achieve further consolidation of the metal and instead, starts to degrade the aggregate by crushing the aggregate.
2. If the material fails to attain refusal it shall either be:
   1. Further compacted, if the material is suitable, to improve the bearing strength.
   2. Excavated and removed from site, then backfilled suitable granular material to a depth necessary to achieve the required compaction.
3. All backfill shall be compacted in lifts of not more than 100mm.
4. The subgrade area between the formed kerb and channel and the road shall be trimmed, shaped and compacted to design level to provide uniform support for the basecourse.
5. Where tree roots are found in the subgrade or pavement area during excavation, Council's arborist shall be contacted for advice. No roots shall be cut without the prior approval of the Engineer. 

Definitions in this section

Council

Design

Engineer

Pavement

Road