One of the highlights of 2017 was being involved in the Sydney Metro Geotechnical investigation in Sydney Harbour. Numac was presented with an opportunity to use one of our Sonic drill rigs from a overwater in close proximity to the Harbour Bridge. The catch was that the works had to be done from a floating barge as the sea floor conditions at the location made the use of a Jack up Barge problematic.
Numac assembled a specialist team of rig operators and safety personnel to work with closely with our client on a comprehensive safety plan and drilling methodology that would give us the best chance of success.
Floating barges have been used for Geotechnical drilling purposes frequently in the past, however these locations are usually still water environments such as lakes and and rivers. This project would involve setting up the barge in an environment that was heavily impacted by weather, commercial shipping and tides.
In order to mitigate these variables the works would be undertaken late at night when commercial and recreational shipping was minimal. The weather was closely monitored and emergency crews were in place to assist in the event of problems with the drilling process. A very finite window was available for the drilling. One way or another the rig and barge needed to be off the location in the early morning hours so the shipping routes could be reopened. This was no negotiable.
Numac hand picked the crew for the job. The 3 man drill crew had over 30 years drilling experience and on shore support team of operations and OHS managers an additional 30 years.
Overall the drilling was a resounding success and demonstrated that despite the challenges with careful planning, great operators and a commitment to safety, significant challenges can be mitigated to great effect. The Sonic drilling technique proved to be highly effective in obtaining full sample recovery from the sedimentary layers and down into the bedrock.
The accompanying video is a mash of footage taken by our client and Sydney Metro and was originally distributed through the Sydney Metro facebook page and National news broadcasts.