Chair Schulman questions how Legionella enters and grows in cooling towers
Schulman asks about Legionella entry, growth conditions, and water temperature ranges. Schiff provides the range of 68-113 degrees Fahrenheit and explains about half of cooling towers operate year-round, with inspections planned accordingly.
I have a lot of questions, so I'm going to ask a number of them, and then I'm going to do, as the speaker did, let my colleagues ask, and then we'll go to a second round.
How does Legionella first enter a cooling tower or water system?
Are there ways to prevent the initial growth?
Yeah, thank you for the question, Chair.
Legionella bacteria is found ubiquitously.
It's common in the environment, and it can basically contaminate warm, stagnant water, which is found in cooling towers.
With what water temperatures are most conducive to Legionella growth?
I presume there's a certain turning point there.
When is the water in a cooling tower most likely to reach those temperatures?
So those are two separate questions.
You're right.
It is warm, stagnant water that is the most...
Suitable type of environment for the...
I mean, does it...
Like, is it at 85 degrees, then that's more likely, or is it...
I mean, or it just...
It doesn't...
I mean, I'm just trying to...
Yeah, we can get back to you on the exact temperatures, for sure.
That would be...
Yeah, that would be helpful.
And when is the water in the cooling tower most likely to reach that temperature as it's sitting there?
That's...
Because it takes a while, right?
That's right.
It may not be the first day of when it's hot.
It may be the second day.
Let me pass it over to Deputy Commissioner Branshaw.
We can get you the temperature ranges, but I think what's important is that the council has recognized that the cooling tower is an ideal environment for the growth of Legionella bacteria.
And that is why you have set out such detailed requirements for the owners to constantly monitor and maintain those.
And in our regulations, we set out further details.
And this is so important because the owners have to maintain these cooling towers literally every single day.
They can't let their guard down.
For the very reasons that you say, Chair, the cooling tower holds a tub of warm water.
And that is why they are constantly treating it.
And really the system has, you could say, belts and suspenders.
They're doing visual inspections.
They're adding biocide all the time.
They have a protocol that they have to develop for their specific tower, their specific cooling tower system, and how it operates at their specific building.
Because we know that there is so much risk.
And that is why there is such detailed oversight required by the owners.
No, and I appreciate that, Commissioner.
I just, you know, for educational purposes, I think it would just be good for us to kind of know this.
I understand what you're saying exactly, but I think it helps with the process of just the layperson, too.
I mean, just to get a sense.
Like, it's not, when it's 30 degrees out, you're not going to have Legionella, right?
So what we know is that typically when we have these clusters, they're happening during the summer or the late spring.
And so, yes, absolutely, the warmer the water is, the more likely it is to harbor.
And it's when they actually, now let me ask a question.
My understanding, I may be wrong, is that the cooling towers don't function unless, because they function to cool the building off, right?
So it wouldn't function necessarily in the winter.
Is that sort of, so it's when they actually are.
Let me hand it to Deputy Commissioner.
About half of the cooling tower systems in the city operate.
year-round and about half are seasonal.
I can give you the temperature, 68 to 113 degrees Fahrenheit is the range.
And you're right also to say that as our climate is warming, we see additional risk.
And so that is why we were so supportive of your bill last year to increase the sampling to monthly because it gives owners in that whole monitoring and maintenance program, gives them more information every month.
They're getting more information as a check.
How is their constant ongoing monitoring and maintenance program?
How is it going?
They're getting more information about that and able to make adjustments to their program.
To your point about some of them operate year-round and some don't, you have, I assume there's a list of them, right, of which ones operate year-round and which don't.
The ones that operate year-round, do they get more, do you, are you more,
involved in making sure that they are complying that the ones that don't operate year-round when they're not operating they're not operating right so
but are you more vigilant about the ones that operate year-round so we we are vigilant about all of them right and I didn't mean to but we but so the one so we this is how we plan our inspections so we want to we want to inspect when they are operating right
and so we are that's that's how we plan our year so the ones that are operating all year we can we can do those inspections.
in the cooler months and the ones that are operating only in the warmer months, we focus the inspections at that time.