A few weeks ago we had to lower a worker into a confined space. The space had a 2'x2' opening with a ladder going down about 10 feet, then the space went about 20 feet vertical.
Tripod set over 2'x2' entryway.
4:1 pulley system set at top of tripod.
1 belay (safety line) anchored on beam near tripod.
After the entrant got to bottom of ladder, he made his way towards end of space about 20' away. What happened as entrant moved away from ladder was the 4 lines on the pulley system started rubbing on one side of the entrance hole causing a lot of friction. The entrant kept calling for more slack even though he had plenty. Due to where the friction point was, there was no place to add a edge roller or anything.
This is hard to explain so I am including a hand drawn picture to better illustrate.
I been trying to think how to avoid this friction issue in the future, one option I can think of is to use a in-line 3:1 (Z-rig) which would have 3 less lines for less friction.
Have you encountered this scenario, and what would you do different?
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11-26-2012, 09:01 PM #1
Confined Space Scenario
11-27-2012, 12:14 AM #2
- Join Date
- Feb 2011
Assuming that this was NOT a real or potential IDLH atmosphere, and that adequate ventilation was in place (along with other hazard control measures, such as energy/power control), I would have had the worker disconnect from the pulley system once he got to the bottom. In fact, the way you explain it it sounds like the worker climbed down the ladder. That being the case I wouldn't have hooked him to the pulley system in the first place.
He simply climbs down the ladder (that's one point of contact) and the belay line, connected to the dorsal ring on his harness, protects him during the climb (that's his second point of contact). If he slips or the ladder breaks then the fall would be arrested on the belay line.
Once he's on the bottom (assuming there are no further fall hazards) the belay line is no longer needed to provide "fall protection" and it magically becomes a simple tagline, and he can have all the slack he needs to move to the far side of the space... just be sure the tagline doesn't get tangled around objects in the confined space.
Now if during the entry he suddenly needs rescue, simply perform a non-entry rescue by "ganging on" your pulley system to the belay/tagline and start raising. Throw a progress capture (aka ratchet) on that line too and you can perform all the resets necessary to lift him all the way out... all while never leaving the safety of the area outside the confined space.
Yes I know that when performing the non-entry rescue the victim is being raised on a single point (one rope, no belay) but that has to be balanced against the value of reducing the risk to the rescuers, the number of rescuers required and the speed of the removal (this is a very fast operation that can be done with 1 or 2 people).
Certainly there are some other variables that could alter this plan but it's a good 80-90% solution.
Hope that's helps.
11-27-2012, 01:55 AM #3
Good Feedback Dave. I agree with you as what you say is how we were trained to do it in CSRT training, but unfortunately, the company paying us requires the worker be on the line at all times.
I should add that the confined space is normally full of water. The space is drained, then we set up our equipment, all the while the space starts filling with water again so drowning is a possibility. We do set up ventilation and monitor the atmosphere prior to entry, and during entry.
11-27-2012, 09:58 AM #4
- Join Date
- Oct 2002
- Port Allen, LA
As long as there aren't any obstacles in the space for the belay/retrieval line to get hung up on then there is no real issue here. Like Dave said, he climbs down the ladder or you lower him with your B & T. He unhooks from the B & T, leaves the belay/retrieval line attached, does his thing and comes back to either climb the ladder or be raised by the B & T. If he can't get out on his own then use the belay/retrieval line to raise him back up. A MPD used on the belay line makes this a simple operation or you can piggy back the B & T as Dave suggested.
There is also one little known technique that would work here. Since the space is filling up with water and there is a possibility of drowning then OSHA requires him to be wearing a PFD (29 CFR 1926.106). Let the space fill with water and grab him when he floats to the top......LOL
11-27-2012, 05:28 PM #5
I would have lowered the entrant on a MA system, attached to his front low attachment point with a retrieval/belay line attached to his dorsal. When the vertical lower was completed, the entrant comes off the MA (main line) and stays on the retrieval line. To be OSHA compliant (not sure about Cali OSHA, if they have additional standards) there needs to be a system in place to perform a non-entry rescue of the entrant on the retrieval line. That would be as simple as hauling up the now detached MA system and piggybacking it to the retrieval line or having a second MA for this purpose.
That's how I roll.~Drew
11-28-2012, 09:04 AM #6
- Join Date
- Apr 2003
- Bay City, MI
I work part-time for a private company that does Confined Space Rescue standbys and we see this scenario a lot. Typically the worker will climb down the ladder and will have a belay/retrieval line attached. We normally have a haul system ready and we will be harnessed up and ready to go if the worker would need to be rescued.
11-28-2012, 10:55 PM #7
- Join Date
- Dec 2009
MichaelXYZ, the quickest way to eliminate this friction point is to remove the MA system. Like others here have recommended, the simplest solution is belaying the worker as he/she lowers into the work space and attaching MA systems to the belay line, as necessary. You stated the client required all CS entrants to remain attached to the MA system during lowering, working, and raising. In this case, it may have been beneficial to all parties to bring this problem (friction to rope at the edge) to the attention of the client and recommend alternative methods of entry. NOTE: don't just bring problems to light, bring potential solutions to the problem with you!
Also, rsqman brought a potential solution to the table for the water intrusion into the space. Yes, this might be an OSHA related problem; however, I see the problem more as an OSHA hazardous energy issue. Alternatively to life jackets I'd recommend pumping the water from the space, eliminating the hazard.
11-29-2012, 03:52 AM #8
I found everyone's input very useful and many valid points. I will discuss this issue with my supervisor.
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