BUTTERFLY VALVE USES

I got a bit of education in sewerology today, courtesy of a crew from the city sanitation dept., or Public Works, or whatever. They were involved in some operations at a nearby intersection, and my curiosity was too much ... I had to find out what they were up to. Turns out the guys operating this truck were running a video camera through the main sewer line, and monitoring what it "sees" on a TV screen like this.
The sewer system in our neighborhood is old -- probably at least 60 - 70 years -- and consists of 6"-diameter sections of clay pipe joined together. (Newer ones are 8".) That provides many small gaps for roots to invade the line, among other things. Cracking of the clay pipe sections is another form of possible damage. So, after noticing a good many root problems, they had another truck and crew come in to run an auger up the line, starting from a manhole one block "downstream."
When I asked one of the workers why they were doing this now -- were there complaints from residents, for instance? -- he said no, the city is getting ready to repave the street and they want to check and see that there aren't existing sewer line problems which would require digging up the street soon after the repaving had been done.
The other thing that was new to me was discovering that at each intersection, where a manhole provides access to the sewer line, the 6" pipe is open. The upper half of it, that is. Which means that the effluent is visible as it flows downstream. I asked the guy if that took some getting used to -- working in an environment which involves pretty close contact with one of the more nitty gritty or seamy sides of life.
"No," he said. "You get used to it. You get so you could stop and eat your lunch right here, right now. No problem."
Sounded kind of like something out of that TV show which Mike Rowe does -- "Dirty Jobs." He seems to have quite a following, too, which would seem to indicate that down & dirty subject matter -- what goes on in the sewer system for instance -- may be somewhat repulsive, but it's still interesting to a lot of people.
BTW, there was a steady flow of water ... or whatever ... all the while as I was observing the sewer activity.

I'll bet sewer crawling remote camera bots almost make being a plumber fun.