Carroll Cave trip report 2024-01-06 Data logger service

Time in – 9:10am, time out – 2:15pm

Participants – Bill Gee (Trip leader)
Mike Kovacs
Candace Kovacs
Jack Rufener
Matthew Hernandez

Twice a year I have to visit all of the data loggers in Carroll Cave. The memory in them will hold about 7 months of data before it starts to overwrite. I do these trips in early January and early July every year. The two sets of data are combined to create full-year graphs of the water levels in the cave.

There were originally eight people signed up for the trip. On Thursday I got an email from one saying she had just tested positive for COVID and so could not make it. Saturday morning we got a message from another person saying their “Check Engine” light had come on while driving to the cave, and they would not be able to make it. The third person was a no-show. When I got home I found an email saying that she had injured a hand and was not confident she could deal with climbing the ladder.

I drove to the campground Friday afternoon, arriving about 1600. It was snowing and raining in Kansas City when I left. Shortly after passing Clinton, MO, the precipitation stopped. The temperature was just a few degrees above freezing, so the roads were not slick with ice.

After setting up the camper, I opened the cave and hung the rope in the shaft. I sprayed some WD40 in the padlocks. After dinner Mike Kovacs arrived. He brought parts for a DistoX-BLE. I assembled it for him. I managed to shred the ribbon cable for the accelerometer, so the device has only one way to measure vertical angles. I will see about getting a replacement ribbon cable.

Overnight was chilly, but the temperature stayed above freezing. When I did my exercise walking early morning, it was overcast, about 32 degrees and no wind. The weather forecast had mentioned the possibility of some rain. It did not rain at all overnight. There was neither dew nor frost.

Matthew and Jack arrived later Friday evening and spent the night camped in their trucks. Candace arrived Saturday morning. We were all geared up and ready to cave by 9:00am. Since that was our meet-up time and there was one more person yet to arrive, we got into the silo to stay a bit warm and chatted for a while. At 9:15 the last person was not yet there, so we started down into the cave. First person in at 9:20, last person at 9:40. I was the last person down. Just before I got on rope, I checked outside. Our late person had still not arrived.

At the bottom of the ladder we found a ring-neck garter snake still alive. Candace found and photographed several grotto salamanders. At the end of the trip we bundled the snake up in a beanie. It got a ride home with Candace to start a new life.

The first thing I did was to download data from the barometric pressure logger and the water depth logger in Thunder River. Next I set out an environmental data recorder built around an Arduino microcontroller and some sensors. There is a cave intrusion detector which needed new batteries and a memory card exchange.

The cave intrusion detector did not light up when I approached it, which is unusual. It should be able to run 6 to 7 months and last was serviced in early July. I installed fresh batteries and a memory card, but it did not start up. After a few retries I gave up. I packed the detector out of the cave for further diagnosis.

We left the ladder at 10:00 heading for the Rimstone Room and the data logger in Carroll River. It was a quick trip, about 30 minutes. I downloaded the data logger. We all went over to the big rimstone formation where Candace set up a bunch of lights to shine through the rock. She got some very good photographs.

The trip back to the ladder also went quickly. We arrived there at 11:05. Lunch was declared! After everyone had some food, we left at 11:30 heading to UL2. We arrived at the data logger at 12:10. There was plenty of time, so we went on to Convention Hall. Jack and Matthew went up to the overlook for some photos while Candace took photos around the waterfall. The waterfall was flowing but not much more than a fast drizzle.

During the trip from the ladder to UL2 we counted 24 fish and 4 salamanders. One of the salamanders was a juvenile. In UL2 from its entrance to Convention Hall we counted 34 fish and 1 salamander.

On the way out of UL2 we stopped at a formation area. I showed everyone where a pocket of cave pearls is. Candace took a bunch of photos of the area. Mike used a selfie stick to lower his phone down the hole where the cave pearls are. He got what are probably the first good photographs ever taken of them.

We stopped for a few minutes at the formation area at the entrance to UL2. Jack and Matthew went up the hill to have a good look. Neither had ever seen that formation area. From there we made a beeline to Thunder Falls, arriving at 1:15. I tried to download the data logger, but it just gave a failure indication. Several tries, including wiping everything wth a towel, did not get a good download. This logger may need a battery change. I brought it out of the cave for further testing.

We were back at the ladder by 1:45. Everyone geared up and climbed out. The last person was out of the cave at 2:15pm. I spent the night at the campground and everyone else drove home.

Checking the cave intrusion detector, I found that the old batteries were almost completely drained. They were down to 0.77 volts. That is so low that the charger did not recognize them. The fresh batteries showed 4.07 volts, which is a full charge. The intrusion detector did not come alive even when I plugged it into a computer. Something is not right with it.

The memory card from the intrusion detector shows events through October 2023, then nothing. I know there have been cave trips since then. The device was working normally when we went by it at the bat census trip in late October, so it must have died soon after that. At least this time the memory card contents were not scrambled.

The memory card from the environmental data logger appears to have nothing on it. That device has given me a lot of trouble. Troubleshooting is needed. While it was running it displayed the readings once each minute. As expected, the relative humidity level was 100%. The VOC measurement was 0. CO2 measurements started around 750 ppm and went up to about 1200 ppm. I thought that was a bit low, though perhaps it is correct since there is very little rotting vegetation in the cave over the winter.

At home after a few tries I was able to make the Thunder Falls data logger download.