Friday, October 22, 2010

Rainy day, a scare, and some redemption

Today was tough. Contrary to popular opinion, it does rain in Green River, and while I wouldn't say the forecast got the timing exactly right, it is clear that the general warning is something to take note of. 

The rain was not too hard, and didn't prevent us from surveying, we did a 3-hour ride taking measurements today.   It did, however, turn the dirt access roads to a mud with the texture of warm butter.  This, you can imagine is very difficult to drive on, and we spent quite a bit of time dealing with getting stuck in various places, and did not get to the start of the targeted area of CO2 seepage.  If it continues to rain, it will be somewhat of an issue as it essentially cuts off our access to some areas deeper into the Salt Wash in addition to generally slowing us down.  We have a strategy moving forward to survey areas that are easily accessible in the rain while it is raining and to bolt for the difficult to access areas on the days where we have dry weather.

The other major problem that came from the rain was the impact of sucking water into the sampling tube on the measurements.  This gave us a pretty big scare today as our measurements essentially stopped making any sense, and the problem persisted even running the instrument in the hotel room.  Chris of Picarro, who I have now Canonized as St. Rella, helped me through a process which essentially required opening up the instrument, taking out a piece that had collected the water, and shaking it dry.  It was fairly simple in practice and it entirely fixed the problem.  We can avoid getting water in the system in the first place by lifting the inlet tube up when we walk through the small streams that have now popped up in the area.

Finally, we did have some redemption, as we now think we have solved the puzzle of the rapidly fluctuating CO2.  We ran some tests in the hotel room where we turned the instrument on, held it in the position that it sits in the saddle-bag, and shook it with a rhythm approximating the gait of a mule.  The inlet tube was sticking out the window of the hotel room.  It turned out that if we were facing the instrument while we were shaking it, there were large fluctuations in the CO2 concentration.  If we held the instrument behind our back while we were shaking it, there were no fluctuations.  It just means that the fitting between the sampling tube and the instrument is not tight, and leaks particularly when it is shaken.  Because where this connection is made on the instrument is near to the mule's breathing, we see the rapid fluctuations in CO2 accordingly.  The fluctuations disappear when the mule is standing still .  If this is truly the last piece to the puzzle, it is an easy fix, and we will have some good news tomorrow.

Lin has arrived, so we have a strong team going into the weekend. Wish us luck! 

No comments:

Post a Comment