Trip date: 6 January 2017
Project manager: Bill Gee
Trip purpose: Data logger service
Areas of Cave visited: CarrollPassage
Trip participants: Bill Gee – Jim Cooley – Bruce Archambault – Jack Peters – Kristen Godfrey – Brandon Porter – Jessica Porter
Entry Time: 9:20am
Exit Time: 4:20pm
The trip report: Areas visited – Carroll Passage, UL2, Thunder Falls

Hydrology report is located here —>

This is the annual data logger service trip. Every year in early January we visit every data logger in the cave to download the data. We also put a new battery in the rain gauge logger, and perform any other maintenance that is needed.

This year the tasks included installing a new data logger just below Thunder Falls. The hypothesis is that floods in Thunder River do not occur from high water flowing downstream, but rather from downstream water backing up into the upper part of the river. By putting a data logger below Thunder Falls, we can validate the hypothesis. If the hypothesis is correct, then the data logger below Thunder Falls should show a rise in stream level before the one at the ladder.

This was a day trip for everyone. Jack Peters and I left a bit earlier so we could arrive at the silo in time to service the rain gauge and hang the rope before everyone else showed up. As it turns out, Bruce beat us all there.

The first surprise we had was the new fence lines. The tree line between the silo and Bill Pfantz’ trailer has been completely removed and stacked for burning. The fence that was in the tree line is also gone. A new fence leg with a new gate now runs east and west several hundred feet south of Bill Pfantz’ camper. The old gate near the camper is still standing but has nothing attached to it.

We found that power in the silo was completely out. Jack mentioned that he was told it would be out when he did a photo trip in early November. It may have simply been turned off at the power pole – we did not check.

As soon as we arrived, I went to download data from the rain gauge. It did not work. After several tries I gave up. It was fairly cold, and I thought maybe it would work better in the afternoon when temperatures got above freezing.

While I was working on the rain gauge, Jack rigged the rope in the silo. Jack, Bruce and I all changed into our caving gear. The other four participants arrived by 9:00am.

To install the new data logger, we had a bag of tools, a concrete block and a new stilling well to get into the cave. I tied them all to the end of the rope, then lowered them by hand to the bottom of the shaft. Jack went down first at about 9:20am. When he got to the bottom, he moved the tools and stilling well out of the way.

Bruce was next to rappel. We were not paying attention to his pack and did not realize it was not tethered. It took a fall all the way down the shaft. Fortunately Jack was out of the way, and there was no damage to anything in the pack.

Everyone else rappeled in without incident. We were all at the bottom by 10:00am. I downloaded the barometric pressure logger and the logger in the river below the ladder. We then headed out for the Rimstone Room.

We arrived at the Rimstone Room a few minutes before 11:00am. I downloaded the data logger, then gave Bruce and Kristen a quick tour of the rimstone formations. The trip back went fairly fast. We arrived back at the ladder about 11:30am and had lunch.

After lunch we went upstream Thunder River to UL2. It took us a bit less than an hour to reach the data logger. On the way back out of UL2 we stopped at the formation room to admire the eye candy. We also stopped just outside the UL2 entrance to admire more eye candy.

About 2:30pm we got back to the ladder and had a quick candy bar break. We then hauled the tools, concrete block and stilling well over to Thunder Falls. After a few minutes of looking around, I settled on a flat section of chert located a couple of hundred feet downstream from Thunder Falls. It is upstream from the ladder landing about 100 feet. The water depth is about 12 or 14 inches and there are rock outcroppings above that make good anchors for the top of the stilling well.

The tools we brought included a hammer drill and a 24 inch long by 3/8 inch bit. The first hole took quite a bit longer to drill than I thought it should. Eventually it was deep enough to put a wedge anchor in. We bolted the stilling well to that anchor, then started on the second hole. It soom became obvious that the drill was no longer cutting rock. A quick examination of the bit revealed that the carbide cutting edges were gone. That bit was complete toast.

One bolt is not ideal, but it will do for starters. We decided to set the top anchors and come back another day to finish drilling the second hole. The top anchors were drilled about 1 inch deep by 1/4 inch diameter. A different bit made the work go very fast! Those holes were drilled in less than a minute.

A plastic anchor was inserted in each hole, then a small piece of aluminum was attached with a stainless steel screw. We ran lengths of stainless steel picture hanging wire from the top of the stilling well to each of the three anchors. The last item was to tie the data logger tether to one of the anchors and then lower it into the stilling well.

The concrete block was not used. I brought it along in case no suitable bedrock could be found. Since we found good bedrock, the block was not needed. It is now a new cave decoration! We packed up the tools and headed back to the ladder. Everyone geared up and climbed out. The last person out was Jack at about 4:20pm.

I changed into dry clothes, then took another stab at the rain gauge. It still would not download. Nothing could be done except to change the battery. Unfortunately that means there is no rain gauge data from October 28 to January 6. When I got home I tested the battery, and it was rather low. Not dead, but getting close. Lesson learned – I need to change that battery every 6 months instead of once a year.

After changing and locking up the cave, everyone except Bruce went into Camdenton to El Espolon for dinner.

There is additional work to do on the new stilling well. Besides the second streambed bolt that I mentioned above, we also need to reconfigure the way the top anchors are tied in. I had put a collar on the top of the stilling well tube with some holes in it. Unfortunately it was broken by something when I lowered it down the shaft. We made it work for now, but I want to redo that attachment. A big hose clamp will take care of it.

We did not spend a lot of time looking for fish, but we did see some. They were smaller than I usually see. The largest was about 30mm long. We saw one bat, probably a gray, hibernating on the wall just a few feet from the Mike Roos plaque. I found a few isopods which were only 1 or 2mm long.

There is a new rope light mounted to the ladder. Rather than being stretched straight, it is mounted so that every 20 feet or so is supported by a separate tie-off. The idea is that this will produce less stress on the internal connections, especially near the top of the shaft. The problem we found is that your feet get tangled in the loops as you rappel in. The rope light really needs to be mounted behind the ladder with its own anchors drilled into the shaft. That should keep it far enough from feet that it will not be damaged.