Infrastructure Development Code

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  1. Trenches in roads shall be backfilled and compacted in layers of thickness commensurate with the compaction equipment to a density of at least 95% of the maximum dry density. Field compaction shall be tested as follows: 
    1. For cohesive soils - New Zealand standard compaction test, nuclear densometer and shear vane. 
    2. For non-cohesive soils - New Zealand standard compaction test, nuclear densometer or dynamic cone penetrometer (Scala Penetrometer).

Testing by other means shall be subject to the approval of the Engineer.

  1. Trenches not in roads or paved areas shall be backfilled and well compacted with mechanical equipment in layers not exceeding 300mm thick.
    1. The Contractor shall undertake sufficient tests to demonstrate that the specified compaction standards have been achieved throughout.
    2. Compaction testing of fill material shall be in accordance with NZS 4402  Methods of Testing Soils for Civil Engineering Purposes.
    3. Compaction testing of subbase and base course shall be in accordance with IT-4 Transportation Network of the IDC.

Definitions in this section

Cohesive soil

Contractor

Engineer

IDC

Road