It seems that way sometimes, but this is what you get after working 37 years in the field... and I mention that because yesterday I filed my retirement paperwork... or at least started the process... here to today, gone to Maui... and hopefully be in denial down the road, as in The Nile, as in cruisin' down the Nile in Egypt...
The graphics make answering a question loads easier sometimes... I seriously doubt that there isn't a graphic I can't come up with or draw myself. I've used these job skills to be a teacher now for over 3 decades... and for me, the most fun with graphics is field work I do with landscape photography & watercolors, something I've been trying to master for years, that and the guitar...
Do I sound ready to retire or what? You know where I'll be...
BZ, thanks for the link. Now for a disagreement...I rarely disagree with you, but I want to toss out an alternative way of looking at zoning.
We all know what the Cold Zone is - it's not contaminated and everyone there is OK to work unprotected.
We all know what the Hot Zone is - it's contaminated, and anyone who enters should be wearing appropriate respirators and chemical protective clothing. Further, they should not enter without a partner, without a backup team, without an assignment, and without being monitored from outside the Hoz Zone.
The disagreement part is the Warm Zone. What, exactly, is the purpose of the Warm Zone, and is it really "Warm"? The only part of your diagram I agree with is the Decon Corridor. With the stated and practical purpose of reducing contamination to ALARA levels, that area is clearly a place of reduced contamination. The rest of the Warm Zone, though, not so much.
I submit that except at the Decon Corridor, there is no Warm Zone. What you show as Warm Zone and Hot Zone should be all Hot Zone. Either a particular piece of ground is contaminated, or it isn't.
I'm interested in your take on this - both your personal opinion and any SOG or scientific evidence you can offer to counter my hypothesis.
I need to think about this but for the sake of providing a mindset here, here goes...
NFPA 704 Diamond - Health Ratings
4 = Level A
3 = Level B
2 = Level C
1 = Level D
Hazmat Incident Zones
Hot Zone = Level A or B
Warm Zone = Level B or C
Cold Zone = Level D
The warm zone is also called the contamination reduction corridor. A lot of words to define that there is the possibility to be exposed to hazardous materials, but NOT an IDLH exposure.
So the difference between Hot and Warm zones is the IDLH potential. Folks in the warm zone need to have protection, but not the level of protection used in the Hot Zone. This is case by case specific, dependent upon the product. And at any time, what was the cold zone can be changed by wind shifts and weather changes... So much for zones...
OK, but by definition, Level C respirators are required to a) have cannisters rated for the specific product and b) be used where the concentration of the product is known to be 50% of the IDLH or less.
The Cold Zone tends to become Hot with nothing more than a little extra velocity in the chemical leak, as occurred with the Graniteville, SC chlorine leak every morning when the sun hit the tanker, or when the wind shifts direction, which occurs here every 2 minutes.
Item 6 in the Graniteville analysis is especially important, as the monitors and ALOHA software were wildly inaccurate in predicting how the product would disperse. If the monitors and the modeling software are not reliable, the ability to discern what product is IDLH and what product is not goes out the window. That tends to make the zoning a Hot/Cold decision, with no Warm.
I'm not thinking about a fixed facility/NFPA diamond situation here - I was thinking more along the line of a transportation accident.
Just to add another level to the discussion - if you have a fixed facility with a NFPA diamond Health rating of 1, is there going to be a Hot Zone at all?
you bring up excellent points Ben. I can see myself actually defending your position but plan on making contact with my EPA buddies to go into this a little deeper. I'll let you know what I find out. I'm just a drone, hot, warm, cold... To redefine this is actually pretty cool. Thanks for the project... I have the time. :D CBz