Saturday, February 2, 2019

Diggin’ Up Bones




by JAR



I used to work for a power systems company that manufactured and serviced electric motors and electronic variable frequency drives for use in different industrial applications. Although the company’s main focus was on oilfield drilling controls (top drives, drawworks, mud pumps, etc.), one of the many smaller niches that we had carved out was in controlling the pumping and drilling motors on dredgers.

Dredging is the process where the sediments on the bottom of a body of water are extracted and moved elsewhere. Some dredgers use a large scoop, similar to a backhoe; most of the dredgers I worked on would actually break up the sediment with a large drill and suck it up using essentially a giant vacuum, then pump the material to another location (sometimes the shoreline, sometimes a barge). Along coastlines, this technique is used to protect the shape of the beaches. In Houston, contractors employ dredgers to keep the ship channel deep enough for the large freight ships to safely navigate to the docks. In Dubai, they excavated sand from deep seabeds in order to build a beautiful island shaped like a palm tree. However, there are many drawbacks to the process, and one major one that we will discuss here:

Whenever you dig up the bottom of a bayou, river, lake, or ocean, you never really know what you can expect to find.
Everything that sinks when discarded into a body of water has the potential to be dredged up when the floor is disturbed. That includes trash, heavy metals, toxic chemicals, bikes, cars, at least one ATM to my knowledge, and even human bodies--I understand the latter to be quite a harrowing experience, though it is one that I have not personally had to endure. Items that were long since forgotten are brought up to the surface, and can even cause issues with the dredging process itself by getting stuck in the pumps or breaking the drills. These are the risks you take when you start carving up the bed of a bayou.

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