The ECW sewers are the peregrinations of a mad-man. Identical locations with identical graffitti, incorrect overhead signs and pathways that skip over other routes in ways that you don't suspect; even after you try to draw them.
The sewers have now been tamed.
Locations and directions are correct, however distances are only approximate (map is not to scale).
Original .SVGz file (compressed svg, a vector format) contains high-res location screenshots and other details.