I've always had a soft spot for manhole covers. For one thing, they are the subject of a two-part brain teaser. (Q: Why are manhole covers round? A: Because the manholes are round. Q: OK, then why are the manholes round? A: Because that's the only shape where the cover won't fall through the hole.) For another, they are so basic, just a piece of cast iron, yet have so much variation.
When Abby-the-Wonderdog came to live with me and we began our neighborhood walks, we saw a lot of different manhole cover designs. I don't know much about sewer systems, but I do know there are actually two different sewer systems in town. The sanitary system drains to the sewage treatment plant. It carries sewage from houses and other buildings. The stormwater system drains rain and surface water to creeks and lakes. I'm guessing you can identify the two by the manhole covers, marked S or SW.
(There is at least one unmarked cover in the neighborhood. Who knows where it goes.)
Because of the environmental effects of surface drains, many street drains are marked to remind citizens not to pollute.
Some of the street drains have manholes (and covers) in them. When I was growing up in the Westerwood neighborhood, my buddies and I often played ball (one o'cat, two o'cat, roll-a-bat) in the 300 block of Mimosa Drive. There was a ball-magnet street drain there that regularly attracted our ball. Then someone would have to go up to the Cribbins and borrow their coal-furnace-stoker (a long steel rod) so we could pry off the cover and send someone down to recover the ball.
Many manholes seem to be advertisements for the company that made them or installed them. (Click to enlarge.)
Some of these are self-evident; one took a little research from Google to find out that EJIW is the East Jordan Iron Works in East Jordan, Michigan. Also, I can remember Greensboro from about 1950 on, and I have no memory of the Pomona Foundry. Was it in the Pomona area, maybe near the old railroad roundhouse?
Some manhole covers are quite decorative.
Others combine the ecological reminder into the cover.
This cover points up another interesting point. Note that it is "Made in India". Upon further review, some of the other covers (Capital Foundry and Triad Masonery) are also from India.
Manhole covers seem to be a pretty low-tech item--a slab of cast iron and a little casting labor. It can't take much labor to make one, and there must be a fair amount of expense in shipping the finished product from India (and probably the raw scrap iron from which it's made to India). Just how much can the labor savings be??? This reminds me of the scene near the end of the movie "Battle of the Bulge" where the German tank commander finds a cake that has been shipped from the US as a Christmas present to an American soldier. He realizes the war must be lost if the Allies have the capability to ship this kind of thing across the Atlantic while the Germans are scrounging for gasoline. Is the World Trade Battle at a similar point?
One last observation. manholes seem to be very social. They are often near each other,
and along the Painter Boulevard section of the Hamilton Lakes walking trail, there is a congregation of three Sanitary manholes.
So much for manholes and their covers.