Kingscote Streets Upgrades - Kangaroo Island Council

Table 4.2 Compaction requirements for Stormwater Drainage
Layer
Minimum Compaction Requirements
Backfill to springing line 92% of MDD modified compaction AS 1289 5.2.1
Backfill to 300 mm above pipe 92% of MDD modified compaction AS 1289 5.2.1
Backfill to basecourse - Pavements 96% of MDD modified compaction AS 1289 5.2.1
Backfill to surface reinstatement - other 92% of MDD modified compaction AS 1289 5.2.1
4.3.3 Removal of Redundant Drainage Structures
The Contractor shall excavate, remove and backfill existing pipelines, culverts and drainage
structures and / or seal existing pipes with concrete where identified on the drawings.
4.3.4 Inspection after Excavation
After the excavation has been completed the Contractor shall notify the Superintendent and no
concrete or drain structure shall be placed until the Superintendent has approved the depth and size
of the excavation and the character of the foundation material.
4.3.5 Pipe Bedding – Dry Ground
The bottom of all excavations for pipe work shall be trimmed to the grades and levels necessary to
achieve the invert design levels, shown on the drawings. Pipe bedding shall comply in all respects
with the requirements for Type H2 support as defined in AS 3725-1989 Loads on Buried Concrete
Pipes and shall consist of 75 mm compacted thickness of pipe bedding sand compacted as
specified below.
The method of bedding shall not be altered without the prior written approval of the Superintendent.
Where, in the opinion of the Superintendent, the material after excavation is unsuitable as
foundation for the pipe bedding, the Contractor shall remove and replace the unsuitable material or
carry out such other procedures as may be required by the Superintendent. Should the existing
foundation be unsuitable and such measures be required, payment will be made for the cost of any
additional work as an extra to the Contract. The payment shall be made subject to the submission
of a fully documented claim as to labour, plant and materials used, checked and certified by the
Superintendent. Prior approval in writing by the Superintendent must be obtained in all cases,
otherwise no claim will be entertained.
No pipe laying shall commence until the bedding has been inspected and approved by the
Superintendent.
4.3.6 Pipe Bedding – Wet Ground
In locations where groundwater is encountered and de-watering is necessary, pipes shall be laid on
an aggregate bed of a depth between 75 and 150 mm. Where the excavation is in soft clays, sand
or other unstable material, geotextile fabric shall be placed over the full width of the floor of the
trench and up the sides to the level of the underside of the pipe, before placement of the bedding
aggregate.
4.3.7 Pipe Laying
Pipes shall be laid commencing at the lowest elevation unless approved by the Superintendent.
Pipes shall be laid on the prepared bedding as specified above to the lines, levels and grades as
shown on the drawings.
Blocks, bricks and other point supports shall not be permitted and where spigot and faucet pipes are
used, the bedding material shall be shaped in such a way that no load is transmitted to the collar of
the pipe, but that the pipe is uniformly supported along the length of the barrel.
Ref No. 20120236SA1 Kingscote Streets Upgrades Technical Specification 15