Saturday, August 6, 2011

Vibrocoring in Southeast Asia

The company I work for (Tetra Tech) has offices and projects worldwide, so it was inevitable that I would eventually travel internationally for work.  Just three weeks ago I found that I would be heading to Thailand to work on a project starting in mid-August.  This work is different from previous projects I have been on.  I will be working in the Gulf of Thailand aboard a 61 meter ship with other Americans, Australians, and Thai.  We will be performing environmental monitoring using sediment sampling equipment and current meters moored on the sea floor.

 I am traveling with my college Rich from Seattle; together we are providing the expertise in deploying and operating our vibrocorer.  This piece of sediment sampling equipment is designed to vibrate a 4” diameter pipe into the seafloor.  The sample is then recovered aboard the ship, extracted from the pipe and analyzed.  It sounds relatively simple, but believe me there is a lot that can go wrong.  At the heart of this system is a 230V 3phase eclectic motor with counter weights.  When powered on, the device shakes VIOLENTLY, generating thousands of pounds of impact force.  It is this vibration that allows the device to drive itself into the seafloor but at the same time it is essentially trying to self destruct.  

The external water pressure at depths we will be working is over 250psi, while this is not all that great, it is it high enough that water will try to squeeze through any O-ring that is not properly sealed.  It is for these reasons that we deiced to have a second vibrocorer built.   We didn’t think it would be a good idea to travel all the way to Thailand and have no backup if the equipment were to fail.  I have spent my last two weeks franticly trying to get a second unit built and gather all the parts, tools and material that need to ship to Thailand.  The Vibrocorer is a custom build so finding a machinist that could source the material and build a new one is two weeks was quite a challenge.

To make things more complicated, I am on my way to Kodiak right now, meaning that it is up to Rich to get all the prep work finished and the shipment ready.  In the mean time I will try to enjoy my vacation in Alaska and hopefully not wake up in the middle of the night wondering if I have all the spare O-rings I need.

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