Sunday afternoon silt-out at the Bats

[Serota]

My buddy and I were enjoying a pleasant dive in the Devils System yesterday and were near the Bats (Hill 400 line) when in the space of about 5 seconds we noticed things getting cloudy and in another few seconds viz. was zero. We were close to the line and having gotten a firm grip on it, I waited for my buddy to turn the dive and come back to my position, which is exactly what happened and we exited without further incident. Later on we talked to 2 other divers who were doing the Bat circuit in the other direction who also had to turn their dives.

This was my first real-life experience with unexpected zero viz. and made me glad for all those drills we did in training classes. We don't know what generated the silt, but the prevelent therory is that someone was "digging around" in a small tunnel upstream of us. It was impressive how fast the silt hit the fan even in a large, high flow passage.

Comments?

Something like that happened at Jackson Blue last fall. Me and AL scootered to the Trash Room. When we got back to around p700', vis was bad, and at p500' it was just a few feet. There was a team of Apprentice divers at p400' fooling with a spool, running it from the Main Line to the Siltout Tunnel entrance.

After the dive I asked them what had happened. They said p400' was as far as they got in, and they had assumed I was chewing up the cave with my scooter.

[BgDadddy]

Anything can silt out if it gets trashed bad enough upstream... My first time in the mud tunnel at Ginnie, when I turned the dive, the silt followed me out and there was almost no vis back at the gold line for a couple minutes.

Fortunately, it clears out in just a couple of minutes in there. If you had of just held onto the line for a minute or two, I'm sure it would have been fine again and you could have continued with your dive.

Rick

[Limestone Cowboy]

Things do collapse from time to time, not all silt outs have a diver at the center of them. Sort of scary if you think too long about it.

Anything can silt out if you trash it bad enough upstream...

I don't know if you misunderstood my post, but I didn't trash it, and I know AL didn't trash it. Since there was nobody else upstream of the siltout, it had to be a collapse.

[Kelly Jessop]

Things do collapse from time to time, not all silt outs have a diver at the center of them. Sort of scary if you think too long about it.

Yep seen that first hand twice. Things sure go black in a hurry,and don't clear out.

[johnm]

I was in the Devils system a few years back when the same thing happend to me. We were scootering up the main line about 500' or so past the key hole and the water went from crystal clear to grean (like being hit by a wall) in a few sec. We keep going, the noticed debry floating past like small twigs and old leaves. At this point vis went to 0 FAST. So on the line and a nice swim out. This happend during a time of heavy rain and floading for sveral months before. Later that day I was told it was river intrusion from somewhere way upstream. Made since since, with the sticks and leave blowing by. Also, the flow was strong and I dont see any was a diver could silt out that much of a high flow cave for a that long of a period.

[BgDadddy]

Anything can silt out if you trash it bad enough upstream...

I don't know if you misunderstood my post, but I didn't trash it, and I know AL didn't trash it. Since there was nobody else upstream of the siltout, it had to be a collapse.

Maybe I worded my response the wrong way. I never thought you did... I was speaking more for the original poster and whoever was upstream of him at Ginnie. Reread that post. I changed it to reflect what I really meant.

In your case it probably was a collapse (or a team upstream from you).

Rick

[Jay]

That is exactly why line drills are taught. Stuff happens.
Good reactions by you and your buddy.
As long as everyone reacts like they were taught and do not do anything unexpected then it is no big deal, just another reminder that you have to be mentally prepared on every dive.

Another place you need to be aware of is right at the end of the Peanut line during a heavy rain. Almost guaranteed to get very 'Milky'.

[akcaver]

Serota,
I remember during a solo dive at Ginnie on the Hill 400 line a few months ago the viz dropped from unlimited to about 10 feet really fast, and it lasted for 50-100 feet, close to where you described. Its from a river intrusion right there, and it wasent that bad back in November when i did this. But with the rain thats been going on lately it makes sense that the intrusion is much worse right now. I have been in quite a few instances where the no viz training comes in handy