Editors Note:Â This is Part 2 of a multipart series of training points learned from an actual incident. Â Click here to view Part 1 including news video of incident. Â Sometimes there is not enough emphasis on the basics such as metering – which aid in your survivability profile and decisions such as PPE, Ventilation, and decon of both personnel and victims.
Confined space rescue is generally placed in the technical rescue discipline, however anybody that instructs or has been on confined space incidents knows that hazardous materials are involved, perhaps, more times than not. This was true for the above incident we had in Scottsdale AZ on August 25, 2014. A worker entered a 3â€™x3â€™ entrance to an approximately 6â€™x6â€™ sump area to retrieve a part number off of a pump when he became overcome by high levels of hydrogen sulfide. Another worker (who happened to be his father) noticed him to be in trouble and entered the space and assisted his son out of the well but was then overcome himself and in so many of these situations, a third worker saw the father in trouble and entered to try and help and was overcome and fell on top of the father. There was enough sewage water in the sump area to cover almost both bodies. First crew onscene could not get too much information from the son because we was very altered and was immediately rushed to the hospital, but we were fairly certain there were two victims down and the Captain declared this an active rescue.
Initial readings at the top of the entrance were 200ppm of H2S, 50ppm HCN, 700ppm VOCâ€™s and 19% Oxygen.Â The Captain was preparing his personnel to enter the well with a full compliment of confined space gear including supplied air & comms, meters, and PPE (Tyvek & gloves).Â
Entering dangerous H2S atmospheres a level of H2S gas at or above 100 ppm is Immediately Dangerous to Life and Health (IDLH). Entry into IDLH atmospheres can only be made using: 1) a full facepiece pressure demand self-contained breathing apparatus (SCBA) with a minimum service life of thirty minutes, or 2) a combination full facepiece pressure demand supplied-air respirator
One thing that is always considered in confined space is rescue or recovery.Â Considering the fact it had been about 20 minutes since the call came to dispatch, the victims were submerged in water (sewage) where we could only see a leg, and high levels of H2S we then declared this a recovery.Â Which allowed us to think about the risks involved to our members in this operation.Â One thing that slowed us down a bit was the fact we were getting 50ppm of HCN (IDLH of HCN is 50ppm).Â It is common to get an HCN reading when you have high levels of H2S, but do you disregard what your meters tell you or do you prepare as if itâ€™s there?Â You could use a different meter to clear it and that is why we (Phx region) uses two different meters; for redundancy.Â We also considered the PPE (Tyvek & gloves) inadequate for this operation, especially with raw sewage at the bottom.
Two things we accomplished immediately were ventilation and constant metering.Â When ventilating a con space the decision of whether to supply the ventilation or exhaust should always be a concern.Â We chose to exhaust but that meant we needed a corridor to exhaust it to and make sure that no one entered that area, which actually proved harder than it sounds.Â Various people, who were allowed in the hot zone, could not figure out why we had hazard tape around a large area and consistently entered or crossed area.Â
Points to consider:
- Always: Rescue or recovery.Â Be realistic about survivability profile.
- On con space calls, it makes sense to establish a hazard group for dealing with the hazmat portion of the incident and set-up a rescue group for dealing with the technical rescue side.
- When meters give a reading that is suspicious, conduct some research on why.Â Use a different meter, research the possibility of cross-sensitivity, or deal with it as if it were there (error on the side of caution).
- Prepare back-up teams in case the first entry team cannot accomplish everything.Â This is something we always consider with our high heat in the summer.
- Be aware of the dangers of H2S, it gives olfactory breakdown and paralysis at levels around 150ppm (anyone working around the entrance had to be in SCBA) It is also very flammable with 4.0 â€“ 44.0 flammable range.
Next: Part 3 -Entry