Sewer system entrances

Usage examples of manholes.

Once I get to that neighborhood, my map tells me where the key manholes are and, by running tests under those manholes, I can narrow it down even further.

Newton had its very own sewer system with its own manholes, which made things confusing.

By now it was three in the morning and we had about eight manholes to check.

The holes I chopped in the ice were as round as manholes, and about half the size.