Apostles is a special place, I'm alright giving hints for drains but because someone has recently pieced of one of the entrance portals (removing etched in tags from the 60's in the process) I can't really give out any hints. I've got a post about it that gives a better idea of the area but other than that you're going to have to find it for yourself, like myself and others before you did.
Sorry if this answer is a bit of a let down, but i can't really say much more about it, given how prone to vandalism it is.
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