How much Cvirus comes up from the sewer?

This isn't news, so if wrong subforum, mods plz relocate.

One of the things my company does is smoke testing of sewer systems. All of our smoke testing jobs are on an indefinite delay because of the virus. For those unfamiliar- smoke testing is a process where we force a bean oil steam (non-toxic and biodegradeable version of fog machine oil) into the sewer system so we can find and record leaks (what we call 'infiltration') on the surface. Everywhere the 'smoke' (steam) comes out, sewer gas is also necessarily coming out. Usually its just from manhole covers, roof vents and broken cleanout caps, but there always seems to be a handful of houses/businesses with an unused drain somewhere where the water trap has dried out leaving an open airway directly into (and more importantly out from) the sewer. Given that Cvirus is known to stay active in human feces for long periods of time, it would be unwise to force sewer gas into habitated buildings right now.

But sewer gas doesn't only come up when we do smoke testing. Sewer systems are huge interconnected ungerground tunnel systems. A system thats working properly (ie: running at or below designed capacity) has air flowing through it as well as wastewater. Subject as it is to pressure differentials from temperature, rising and falling water levels, pump stations and any number of other reasons, sewer gas will regularly emit from any open airway to the sewer.

Large, complex buildings like schools, hospitals, airports, malls, office buildings seem to always have at least a couple 'leaks' when we do smoke testing. Its usually a janitors closet, bathroom or utility room with a floor drain or dink that rarely or never gets used. On average, it takes about a month for the water trap in a typical drain to evaporate down to where there is an airway to the sewer. So, generally speaking, any drain, sink or shower becomes a potential airborne infection source if it isn't being used (or having water poured in it) monthly. Toilets can go a lot longer because they hold more water, but they become a source as well when they eventually evaporate out.

Just food for thought, really.

 

Years ago, tons of roaches were POURING out of a man hole cover. It was disgusting, horror movie level.

 

Was it CA? We do work in CA. I've been in manholes there where you couldn't even see any concrete as everything was totally covered by roaches. Every time you pick up a tool, you have to shake the roaches off first. Crazy infestation down there. I only ever see one or two at a time in WA and OR though. Which is wierd because being underground, the temperature and other 'environmental' conditions in the sewer should be about the same everywhere...

 

SW Florida.