Protecting the pipe
Following the pipe pull and pipelay out of Darwin Harbour, the
pipe will be protected with filter and armour rock.
The previously stockpiled rock will be re-handled and
transported to the rock load out facility. It will then be loaded
onto Boskalis’ side stone dumping vessel (SSDV)
Ndeavor
, which
will be used to install the rock into the trench to protect the
pipeline.
In areas that are too shallow to accommodate the
Ndeavor
,
two shallow drafted non-propelled split hopper barges will be
used to install the required rock protection.
At the shore approach area, backfilling is also required in order
to protect the pipeline. This will be achieved using a combination
of material recovered from the temporary works and imported
materials.
The subsea rock installation work is expected to commence in
Q3 of 2014 and be completed by the end of 2014.
Environmental considerations
As with all offshore capital projects in Australia, there are
numerous detailed environmental requirements. The composition
of the Dredging and Spoil Disposal Management Plan (DSDMP)
was a major task and involved a number of experts both in-house
Boskalis (Hydronamic) and external. The DSDMP is the ‘Bible’ for
the dredging operations on the Ichthys project and was strictly
adhered to.
In addition to the DSDMP conditions and requirements,
numerous other environmental works were undertaken. This
included groundwater monitoring, fauna surveys, marine fauna
observation and not to mention the marine fauna plans to deal
with what would need to happen in the event that a vessel came
across dolphins, whales or dugongs. As well as the usual Australian
marine fauna, there was also the threat of the native saltwater
crocodiles (salties), which had to be catered for in all the relevant
plans and procedures.
As we speak (as you read)
At the time of finalising this article, the pipe-pull has been
successfully completed, the dredging spreads demobilised, and
the preparations for the rock load out facility are underway in
order to commence the rock installation with
Ndeavor
.
The challenges faced so far have been met head on and
overcome safely. The Boskalis team on the project now look
forward to a safe and timely completion of the remaining scope
on the project.
Figure 7.
Rock stockpile area.
Figure 6.
Backhoe dredger
Baldur
.
Figure 8.
Backhoe dredger
Baldur
.
Figure 5.
Trailing suction hopper dredger
Queen of the
Netherlands
.
76
World Pipelines
/
SEPTEMBER 2014
