Mine Pit Bathymetry
"No one knows whats been going on down there since water covered it up, it would be nice if there was some way to quantify the changes..."
- Things people say about the Berkely Pit
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Answer: Bathymetry
What is bathymetry you ask? Its like a topographic map of the ground beneath water. How do you get that? Sonar.
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Since flying a drone with a camera around probably won't see below the water and certainly can't map it, we have to use other methods to measure the subsurface. Sonar uses a sound pulse that goes through the water and bounces off a surface before returning to the boat. In much the same way seismic surveys or laser range finders work, we can use that information to measure depth at a point. Put together tens of thousands of points and you have the beginning of a surface.
So just rent a survey boat and put it out there? Well, not exactly. While there are off the shelf boats for underwater surveys, most are not meant for the depths that the Berkeley Pit brings to the table. Even if they were, people don't usually want to loan you equipment that is going in an acid lake for obvious reasons.
Since there are not great options readily available we had to piece together the kinds of equipment that can meet the needs of this unique body of water and put it together ourselves. This USV was set up to run survey grid missions, has an onboard computer to run the acquisition software used by the instruments on board (including an ocean grade sonar system and survey grade GPS) and a radio bridge so that we can remote desktop right into the boat and run all the equipment from the safety of shore. This protects the data collection by not sending it to shore and allows the boat to do its job even if we aren't talking to it at any given moment. A good feature when covering a water surface of 450 Acres, who wants to redo that because something went wrong 10 minutes in?