Airborne Winery Emissions

I’ve got the SF Bay Water Board on my case about stormwater runoff from my winery on Treasure Island. All my winery operations are indoors, to an unusual extent amongst all the wineries where I’ve worked, been a AP, or visited. The potential organic matter runoff from my site would probably be measured in teaspoons. But a Google Maps photo of my roof showed dark stains around a couple of my roof vents, and I’m being asked to account for that, as there could be runoff from the roof that might reach the Bay. It’s black sooty material that’s stuck pretty fast to the vents and surrounding gravel on a flat roof. The vents in question aren’t connected to any ducting – they just connect straight to the open indoor air. My natural gas tankless water heater duct is totally clean. Other than the water heater, the only combustion indoors is my propane forklift. My question is whether there is a known airborne product of fermentation, or other winery activity, that could account for the sooty material on my roof. I wouldn’t expect CO2 to rise thru a roof vent. Alcohol or something else that might be substrate for open air microbial growth? I know there can be sooty growth in dank cellars, but this is a windy, UV-exposed spot. Any theories?

Any way to tell how long that’s been there? Older Google Maps images? Wonder if it was already there when you moved in.

It could be as simple as algae growing in a moist area, and air pollution sticking to the algae.

I would be looking for a new building immediately. Someone wants you out of there. Do you own the building or leasing?

They don’t go scouring google maps photos for no reason. Someone is feeding them the info and they are notoriously for sale.

I’m sure the human feces on the SF sidewalks is more of a threat to the Bay, but those homeless people don’t have deep pockets.

I agree. You need the Google Earth Pro software to do that now. But the current Google images showing the stains are from June 2019. So, whatever it is may have been there before you moved in?

Also, is there a significant temperature differential between the air coming out of the vent (or the vent itself) and the ambient air that could be causing condensation and thus an environment for mold/algae to grow? (Or even a straight up humidity differential.)

It’s definitely my hope that the deposits predate me. I think I’ll put down some new gravel on top of the sooty gravel and hope that there are no new deposits.
I think the humidity differential idea has merit. My building is one “pod” of a former school campus, and there are identical pods all around me that don’t show these kinds of deposits. All of those others are heated. Mine stays cool, so I’m sure I generally have less warm air coming out of my vents. On the other hand, I’m sure that the others aren’t spraying hot water around with abandon while cleaning. There is bound to be episodic steam escaping the vents that is likely to condense rapidly in the generally cool and humid external air. I’m not sure that would amount to a real big moisture addition, on top of normal rain and dew accumulation, but it seems like a plausible hypothesis.

That’s interesting. I do have night cooling. The deposits are at the roof vents where the warmer indoor air exits. I suspect you’re talking about deposits where the air enters the winery? I don’t think I can plausibly claim a direct path from dirty outdoor air to the deposit points if the night air fan is doing what it’s supposed to – blow in cold external air that will sink upon entry and displace warmer indoor air that will rise to exit the roof vents.

I believe the black deposits on the outside of your building are a type of fungus that commonly grows on distilleries, wineries, and breweries.

Scientifically known as Baudoinia compniacensis, or more commonly as Whisky Fungus, it grows where there is alcohol vapor present, i.e. roof vents, doors, windows, walls.

It is not considered to be a health concern and can be removed with a power washer or hand scrubbing.

You can read more about it here:

champagne.gif Max

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That’s a strong hypothesis. Thanks.
I did send samples off to a lab that ID’d it as a different fungus that is ubiquitous and benign. I was able to report that to the Water Board, and, as far as I know, sleeping dogs are laying, so I’m not anxious to amend my reporting. I think it’s possible that you are right but that what the lab picked up was a ubiquitous fungus that was also present.

What is the underlying construction of the roof? Gravel on top of tar? Membrane? Shingles? I agree with the others about mold/microbes but there might be a difference or concern if you have a a) leaky roof or b) failing substrate.