Home Hot Wash THMG126 – Hot Wash: Sodium Hydrosulfite

THMG126 – Hot Wash: Sodium Hydrosulfite


In this episode, Mike runs through a hotwash based on a listener-submitted sodium hydrosulfite incident.

Complete Show Notes

1:20 What is a Hotwash?

  • Immediate after-action discussions and evaluations of an agency’s performance following an exercise, training session, or major event
  • Designed to identify strengths and weaknesses – intended to guide future responses to avoid repeating errors made in the past
  • Bob & Mike want to establish an audio archive of events that have taken place to be passed down from one generation to the next
  • Anybody can submit a hotwash, and you don’t have to reveal any identifying information about yourself or be on the show

3:05 Dispatch Information

  • Time: 7 AM
  • Weather cool and unremarkable
  • Dispatch reports that fumes are coming from a drum
  • Hazmat unit is 15 minutes away – by the time they arrived, they were around 25 minutes into the incident

4:00 Information Received En Route

  • Received via radio transmission
  • Confirms that some kind of gas under pressure is leaking from a drum
  • Transmission was a little unclear, but thought they heard the word “Dirtex”
  • First arriving units are detecting hydrogen sulfide gas
  • Resource officer looks up Dirtex with gathers the following information from its SDS:
    • Cleaning powder
    • Non-flammable – product of combustion with CO and CO2
      • This is interesting because the units were only detecting H2
      • There was no report of the product being involved with fire
    • Ingredients:
      • Sodium sesquicarbonate
      • Sodium metasilicate
      • EDTA
      • Tetrasodium
  • None of these ingredients really fit into the puzzle, and a discussion breaks out due to the presence of H2
  • Started a cross-sensitivity check to see if any of the products of combustion or a reaction might cause the H2 sensor to go off

8:20 Making Entry On-Scene

  • Entry team does an initial hazmat recon in bunker gear and SCBA since the situation isn’t making much sense
  • They see a 30-gallon drum against the wall that’s rusty and has debris piled on top of it
  • They also see liquid on the rim and on the floor around the drum
  • Some kind of gas is pushing out under pressure from the top of the drum where the rust has eaten away the lid
  • Pressure in the drum wasn’t building, and there are no other signs of stress

10:30 Metering and Reading Labels

  • High levels of H2S, but it was sticking around – affecting people within a quarter mile of the drum
  • Normal O2 – no reading of CO, LEL, or VOC
  • Thermal imaging showed the drum was hot – maximum temperature reading of 170 degrees Fahrenheit
  • No pH in the atmosphere
  • Labeling
    • Detailed inspection of the drum showed a label with the following information:
      • CAS number
      • Company name with a phone number
      • Warning label that said: “Water-reactive and will release H2S”
    • LD50 indicated that the product was a solid
    • Also supported the meter’s H2S readings and reinforced the possibility of a sudden reaction
    • At that time, the resource officer learned that it was a 30-year-old drum that was never used – the representative from the company didn’t have any other information

14:10 Identification

  • Based on the CAS number, they determined that the chemical was sodium hydrosulfite
  • SDS provided the following information:
    • Combustible – decomposes with an SSDT of 190 F
    • Slightly alkaline
    • Shelf life
    • Chemical name was actually Virtex – not Dirtex
  • All of this information confirmed the information on the drum
  • At this point, the team feels certain that they’re definitely dealing with sodium hydrosulfite
  • The drum has stopped producing gas under pressure, and second entry determines that the temperature had also started to come down

17:50 Briefing with Incident Commander

  • Incident commander (IC) wants to know what your options are
  • Based on the SDS information and observations, entry- and senior-level personnel on the team provide two choices:
    • Option 1: Do nothing – monitor and allow the product in the drum to safely complete its reaction
      • IC isn’t a fan of this because it would take a lot of time – a few blocks in the vicinity had already been closed off
    • Option 2: Remove product from drum and lay in a pop-up pool filled with water
      • Felt that although it was water-reactive, the large amount of water would pull heat from the reaction, allowing it to pass quickly
      • This would also cause it to produce large quantities of by-product rather quickly
      • IC seemed to prefer this method

20:20 Gathering More Information

  • Attempted to call the company whose name was on the label, but discovered they’re no longer in operation
  • At this point, they decided to call Chemtrac – determined the situation was beyond their capabilities and referred the resource officer to Chemtrade
  • Chemtrade found a contractor in Texas who knew the chemical and was able to provide advice on how to handle the situation – his advice matched what the team was already planning on doing
  • Chemtrade then found an employee from a company who made the product and spoke with him
  • Contractor said that once the reaction was complete, you’re left with a bleach-like solution that can safely be poured down the drain

23:15 Finishing the Reaction

  • Armed with this information, the team moved forward with pushing the reaction to completion
  • Filled their pop-up pool with water and started to put the chemical into the pool
  • They did this because putting small amounts of the chemical in water allowed the heat of the reaction to be absorbed
  • This also allowed them to stop the process in case something went wrong unexpectedly
  • When they finished the operation, they noticed there wasn’t much of a reaction at all
  • Between the reaction that had occurred and the age of the chemical, the reaction was mostly completed by the time they placed the chemical in the pool

24:25 Lessons

  • Constantly compare information for congruency
  • Chemtrac and Chemtrade are fantastic resources
  • Have an understanding of basic chemistry – you can’t have a sulfide by-product if you don’t have sulfur
  • Understand and utilize the resources you have (like SDS sheets)
  • Perform the operation in small amounts and increase whenever it seems safe

Have a question? Send an email to feedback@thehazmatguys.com or leave a message on our Haz Mat Guys comment hotline: 843-628-1484

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