CSB Updates Recommendation Status – 11-09-23

Yesterday, the Chemical Safety Board updated the status from ‘Open’ to ‘Closed’ for of one of the recommendations from the Optima Belle investigation. The change in status of recommendation 2021-02-I-WV-R14 reflects the fact that the National Center for Biotechnology Information has updated the PubChem database entry for sodium dichloroisocyanurate (NaDCC) to reflect the hazards reported by the CSB.

This updated safety information is important because NaDCC is used as a water purification chemical as a substitute for sodium hypochlorite. Organizations that use or sell NaDCC (especially pool/spa vendors and support companies) need to review the revised safety information.

Review - Pool Chemical Safety Redux – 8-9-21

 

A follow-up news story about a ‘chemical leak at a Texas water park’ story calls for an update about pool chemical safety. The new story claims that the chemical release was the result of an improperly installed filtration system. Is that even possible? Sure, it would have to deal with how chemical additives are piped to the their system.

I have previously described here the problems with sulfuric acid and bleach as water treatment chemicals. According to the news reports in this case, those were the two chemicals involved in this incident. It would appear that they were added into the pool water system at or near the water filtration system. Normally, one would expect that they were added at separate times to avoid this type of reaction. Apparently, that did not occur in this case for whatever reason.

If this was a fully automated system, the process control engineer (probably a different title at a water park), needs to go back and ensure that process control system for the water system takes into account any stoppages in the flow of water in the timing between the additions of these two chemicals into the system. If this was a manual system, the problem is more difficult because you may have to ensure that multiple people working the system are in communications about the operations of their individual parts.

If you really wanted to be safe, I would probably design the system so that one (more probably both) of the chemicals would be added into the pool by physically separated systems not attached to the filtration system. This would go back to the ‘opposite sides of the pool’ process that has long been recommended for. This is certainly more difficult and expensive to set up, but it would be inherently safer, something for which chemical process people should always strive.

For a more detailed discussion of the chemical reactions involved and how this incident could have occurred, see my article at CFSN Detailed Analysis - https://patrickcoyle.substack.com/p/pool-chemical-safety-redux-8-9-21 - subscription required.