Excavation of shear keys and embankment undercuts, with removal of any unsuitable material, shall be carried out in accordance with CS-4.10 Undercut for Shear Keys, Embankments and Fill Areas and the profiles shown on the Approved Drawings or as instructed by the Engineer.
Quality control testing to confirm the suitability of in situ materials at the base of the excavation shall be carried out as required by the Geo Professional.
Before the placement of any fill, the base of the excavation shall be inspected and approved by the Engineer.
In addition the Contractor shall comply with the following:
- If more than one type of material is specified then the Contractor shall ensure that the specified levels and grades of the various backfill material types are strictly adhered to.
- If rock fill is to be used for backfill it shall be spread uniformly in layers of less than 300mm loose thickness and compacted to achieve a dense fill with good rock particle interlock and point-to-point contact between the coarser rock particles. Where practical the excavation shall be dewatered prior to placing rock fill but, if that is not possible, the rock fill may be placed below standing water level. In such instances the Contractor shall propose a placement methodology identifying proposed layer thickness and method of compaction for the Engineer’s approval.
- If hardfill is to be used for backfill, it shall be spread uniformly in layers of less than 150mm loose thickness and compacted to achieve a dense fill with good particle interlock and point-topoint contact between the rock particles.
Definitions in this section