Looking at old sewer plans: I've been stumped on the measurement unit for Manhole depth. Sometimes for these old plans it seems that the manhole depth is written with double primes (") in between 2 numbers but at the bottom. Im not sure If this means the number is written in feet and inches or in decimal feet (tenths).?ÿ
If anyone knows how to read old sewer plans (pre 1940s) please let me know.
Also these plans often gives elevation in decimal feet (I assume) in red. The depth is in black. In the examples I attached you can see that sometimes the primes are there and other times the denotation isn't as invasive on the measurement.
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I interpret that as definitely 10'7" deep. Or 10 feet and 7 inches deep. They appear to be consistent with their labeling and annotations using decimal feet or feet and inches. They seem to put 2 dots after a foot measurement when using inches and only 1 dot when using decimal feet. example 136..6 or 453..8 3/4. All of the single dots are decimal feet i.e. 96.21