1. #1
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    Default Usually scenario

    I had too much time on my hands and though of this.

    A contractor is install sewer line in a suburban community. A 18’ x 4’ x 10’ trench is dough, shielding is only present 6’ on one side of the trench. In the muddy trench, a hole drops 8’ down. At the bottom opens on backside of a side passage of an underground cave. The room of the side passage is circular room 12’ diameter and a ceiling of 5 feet. The contract has sealed off the most of the side passage from the rest of the cave. Two workers were last reported in the cave section of the site and are not responding to the radio. How would you in, real life, resolve the situation?
    What would be the textbook approach to a solution?

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    Information man! More information!
    The fact that the trench is DOUGH really raises concerns!!

    Seriously - a "real" visual (vs. my imagination) would be helpful. First - is this a real CAVE as stated or a vault off the side passage? Is the cave/vault/side passage at/below/above the level of the "hole" bottom? Is the 6' shoring from the bottom-up or top-down? Dry hole or wet? How wet/how dry?

    First thoughts = IDLH atmosphere. O2 content too low to support life. Possibly mixed with toxic (explosive?) atmosphere. Knowing your atmosphere is going to be a key first step.

    Has anyone - other workers - been in this section previously? When? For how long? What equipment (previous/current workers) is carried? How long have the workers been out of contact? Has radio comm. been a problem before in that location? What types of stability (soil) issues are there? These are just the starting point to get a handle on a sit. like this.

    My first reaction is to get some help - call in the USAR-type cavalry (if that is not who "we" are). Establish a CP & prepare to be on scene for a while..... Keep people out of the hole until a bunch of the above questions are answered - the layout of the scene does not lend itself to quick retrievals if you have problems w/rescuers in the hole.

    If the cave is a real cave - are there entrances/exits nearby (or even far away)? If so - you might call on the local cave rescue folks - they can give you some beta OR work back toward your location from exit points.

    As we start to answer the above questions we can see what next steps start to look like....

    Gotta tell 'ya - your little hypothetical(?) gives me goose bumps. Scary possibilities.

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    It would have to be handled like a trench and confined space. Vent/monitor and dewater first. Second make sure the trench is secure. We don't have caves or cave rescue teams here so this isn't my forte. Once the trench is secure we would have to take a look and see what we had.

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    The vault begins at the bottom of the 8' drop. The vault is essentially a flat cylinder shape. There are no other known exits to the rest of the cave. The last contact was 30 minutes ago. Radio work normally, most of the time they work.
    Soil was muddy; the equipment is a radio and a ladder in the trench and one in the hole.

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    I have to admit that this little scenario is intriguing and I am interested in seeing how it develops. Even though much of this will likely get into areas outside of my expertise, here goes..........

    This is definitely a multi-discipline situation. CSR, trench, rope, cave(?), underwater/dive(?), EMS (ALS most likely - experience in the noted areas will help (comfort level is better)). As a result - resources are going to become an issue and you will need back-ups (with comparable cabilities) for each "discipline" in case of problems and to rotate personnel. Get them rolling sooner rather than later. Set-up an IC and build out the ICS positions as necessary. A safety officer is going to be key - make sure they have experience (it is going to matter in an incident like this - they MUST recognize hazards quickly). Staging and other key ICS positions are going to be necessary very quickly.

    Key first steps - secure the scene. Keep unnecessary personnel back from the edge(s) so that we don't introduce more victims. Too much chance of instability at the edge(s) of the trench. Begin to monitor the air and ventilate. Frequent monitoring will be key - esp. to see what effect ventilation is having. As noted in another post - prepare to dewater. Plan this in conjuntion with shoring operations (another key activity to begin). Keeping the # of rescuers in the hole to a minimum is going to be important since the likelihood of collapse is going to be high (?) depending on soil type, etc. Operations to shore/stabilize the trench are going to be high on the list since you shouldn't put people in the hole until you have a more tenable situation. A remote camera type of set-up (if available) might be useful so that you can begin to "look around" the more difficult to reach places in the trench without actually putting rescuers in. Talk to other workers - especially anyone who has been in the location below (those who "blocked" the passage?) - what info. can they provide?

    Key second steps - (all dependent on how things evolve). Set-up retrieval and other access systems (ropes/ladders, etc.) to get people into/out of the trench. As things are shored/secured, begin to work into the lower reaches - repeat monitoring and shoring activities. Based on what we find as we get deeper we can evaluate next steps.

    I am still a bit confused about the vault/cave situation. Is there an actual CAVE that joins/opens on the vault at the bottom of the 8' hole?

    The "textbook" is quickly going to become "obsolete" on this. Experience, clear/concise, and well thought-out thinking is going to be critical. Being methodical (don't rush) will be crucial as well.

    Good exercise in critical thinking......

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    Step 1: Slow Down.

    Like ADSN said, it's time to treat it as a trench & confined space.

    Currently in my area our capabilities are very limited in both aspects.

    First, if we have equipment still running like backhoes, let's get it turned off and/or moved away to minimize vibration & noise (can you hear someone calling?)

    I'm concerned about stability of the trench. Since the contractor's working, it's probably during the work week and we can call one of the local lumberyards for plywood & 4x4s -- but's going to take a while for them to load their truck (even if it's not out on a delivery) and get there. Looking for plywood both for ground pads & trench boxing -- what exactly is needed depends on the exact situation. We still have a few old fashion heavy duty backboards that can be used as ground pads along with anything else handy while we continue to assess the situation.

    Once stability has been addressed, we are in better shape for training/equipment on confined space, but I still would have the two other departments in the area that have confined space equipment respond to provide backup & a second sight eyes on what we're doing. Would've also special called in one of neighboring walk-in style rescues for use as the Command/Planning post.

    (There are efforts underway to get the funding for three regional technical rescue trailers which would go to three departments with confined space training already (plus more training to follow), plus a fourth trailer just for sheeting & shoring, which would at least address the material needs for an incident like this!)

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    Question HUH??? Sewers, caves and dough?

    There are not many times when I am ....but this is one of them.

    After careful consideration of the aforementioned scenario...This is best left to an experienced technical rescue/collapse/confined space unit. Stabilize the area. Don't put additional persons at risk of becoming victims.

    I remain by the usually scenario.
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    Thanks to every one for playing with the scenario. Next time, I might check my grammar and express clarity on some details. I intended this to be a trench/confined space rescue. I threw in the cave to throw some people off. The inspiration is from a site in Egypt during construction of a highway. The foundation was built above a cave connecting some tombs. The cave was seal after a short excavation.
    The workers went down do due to bad air(caving term), natural gas or hydrogen sulfide. The trench has a hole, the hole goes down 8’ and opens into a small room attached to a side passage of a real cave. Access to the room from the side passage was mostly sealed. There is a little water, it is not a concern unless the workers or face down. The muddy soil makes it a class C soil.
    A textbook would dictate using a trench team for shoring, a confined space team for the rescue and some one with cave rescue experience to evaluate any dangers at the bottom.
    In reality, I think there are some teams in my area who could perform the task. Trying to figure out about the cave part just adds more time to an already length process. Interviewing the workers as suggested, would clarify the space available for rescue at the bottom. It also would give the confined space team facts need to judge their attempt. In the responses, I notice the experience talking with you guys. My team has never trained for a problem like this, yet.

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    Good/interesting scenario. Particularly good that it has some basis in reality.

    Anytime you start getting well below ground and working away from exits and/or the exit is difficult (vertical/requires raising or ascending of a rope, etc.) watch out. Units experienced in cave rescue are often good resources in this type situation, but when you mix in an IDLH (H2S, methane, low 02 %, CO, etc.) atmosphere that cannot be ventilated well, you need to have rebreather or similar capability [ SCBA or fixed line air supplies might not give you enough supply or be feasible]. Add the possibility of flooded spaces and it all becomes very dangerous and resource intensive. Mine rescue units often have the training and equipment to deal with these situations.

    I have seen abandoned mine tunnels and shafts (some nearly a 100 years old), filled with waist deep water, smelling a bit "funny", filled with collapsing timbers/shoring drawing the curious in for a look.......

    As you noted - the text book(s) can give you guidance, but experience/training is going to help get everyone (at least the rescuers) home alive. A "little knowledge", many assumptions, adrenaline and ego (i.e., not calling for help) get rescuers killed in scenarios like this.

    These kinds of 'what-if's' are good mental exercises.

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    A suburban mom and pop company, has just gone corporate, moved the operation to a new and larger site. A factory/warehouse facility is under construction. The warehouse has been completed for 30 days and is in full use. It is a 2 story structure with a basement, 3 floors. It is of irregular shape, a corporate design, on the outside and has approximately 49,000 square feet of space. There are four smaller office building, the size of a small 2 family house, surrounding the warehouse side of the complex. The warehouse has several partitions inside. The factory side is adjacent to the warehouse. The factory side is approximately 9,000 square feet, 2 floors, no basement, one main corridor with several rooms to the side with very few windows on the outside. The complex is made of commercial brick Type 2 construction and sits on an 800 ft by 500 ft lot. The factory is 85% complete. The company produces specialized industrial cleaning solutions. Qualities of chemicals are received in intermodal containers by rail. The chemicals have additives introduced and are packaged in 5 galloon, 55 gallon drums and a few 1 ton cylinders.
    Friday, 1:30pm an explosion has occurring originating from the factory side of the complex. There is a dust/smoke cloud pouring out from the windows and doors of the factory. People were working near or in the area of the explosion. The construction site manger says a subcontractor crew of 2 were welding on a 27,000 gallon container before the explosion. All but 7 people in the whole complex are accounted. The 2 welders and 2 others from the factory side and 3 from the warehouse side, one in basement. The foreman on the warehouse side heard a boom and rumbling sound before exiting the building. There isn’t a preplan. The owner though it wasn’t needed until the factory was finished. Your department arrives 7 minutes after the explosion.

    What is the textbook way to handle this incident?
    How would you deal with this in the first 45 minutes, if possible with your department(s)? After 45 minutes, the situation changes, to be added later.

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