Kingscote Streets Upgrades - Kangaroo Island Council

All areas disturbed by the excavation and all loose surface material shall be compacted by watering,
if necessary, and rolling with approved compaction equipment to the density specified for filling.
3.3.7.3 Trench Excavation
Unless otherwise approved by the Superintendent, trench work for pipes laid to grade is to proceed
from the lowest point to the highest point in each system.
Trenches shall be excavated to the lines, levels and grades as shown on the drawings. Minimum
trench widths shall be as nominated on the drawings or where no width is shown, as narrow as
practical consistent with good construction techniques.
The floors of all excavations shall be evenly trimmed removing all protrusions, loose soil and debris.
The maximum open trench excavation in any one section shall not exceed 100 metres unless
approved otherwise by Superintendent.
3.3.7.4 Excavation of Rock
If rock, as defined herein, is encountered during excavation and the Contractor considers that the
only practical means of excavation is by rock breaker, jack hammer and/or blasting, the Contractor
shall immediately notify the Superintendent.
If the Superintendent agrees that the material to be excavated should be classified as rock, authority
will be given for the use of a rock breaker, jack hammer and/or blasting and payment will be made
as an extra to the contract based on the volumes of rock required to be excavated at the appropriate
rate in the Schedule of Unit Rates. The Contractor must obtain prior approval from the
Superintendent that the material is to be classified as rock for payment purposes, otherwise no claim
will be entertained. The Contractor is to record measurements for the calculation of the volume of
rock, and submit these to the Superintendent for approval.
For the purposes of interpretation, measurement and/or payment relevant to the term ‘rock’ as used
in this Specification, rock shall be defined as only that material found in ledges, masses, bedded
deposits and/or conglomerate deposits and presenting the characteristics of rock which in the
opinion of the Superintendent cannot be removed for bulk excavation by a ripper dozer rated at net
engine power 230 kW (Caterpillar D8 or equivalent) or for trench excavation, by using a bucket
excavator rated at net engine power 165 kW with rock bucket (nominally 30 tonne excavator) and
would normally be removed by blasting, pneumatic tools or mechanical impactor.
Where, due to limited access, the use of a machine as above is impracticable a side shift bucket
backhoe rated at 70 kW will be approved. If the restricted access is caused as a result of the
contractors previous work and the contractor could have expected rock in the vicinity, the rock would
be assessed based on the previous equipment rating. All trenches in areas with a high likelihood of
rock should be pre-dug prior to restricted access.
Floaters in trenches, foundation or similar excavation shall be classified as rock only when their least
dimension exceeds 0.6 m or where their volume exceeds 0.25 m 3 .
Materials which could be excavated by the above rated plant, such as broken shale, weak
conglomerates etc, shall not be classified as rock for payment purposes.
Measurement of rock excavation for payment purposes shall be made on the following basis:
• The rock shall be measured in the solid form, within the limits of the excavation, before any
backfilling is placed, or new work commenced.
• For bulk excavation, the volume of rock shall be calculated by an independent engineering
surveyor engaged by the Contractor based on the difference between the rock surface(s)
following removal of the overburden as approved by the Superintendent and the extent of rock
or design surface, whichever is less, as approved by the Superintendent
Ref No. 20120236SA1 Kingscote Streets Upgrades Technical Specification 6