Have worked topside lately around Dsanktuary and Aquacave, having to plot their locations for professional reasons. Very interesting opening all grates and manholes along the length. Valuable intel also!
Looking in sewer manholes again
Found this one, which is basically a work of art:
Bit hard to get depth perception from the pic, but the pipe from the left is higher than the rest, and it corkscrews down and around to intersect the others at the appropriate level. Never seen anything quite like it.