Stormcrow, the ones I was talking about are in San Diego too. One started near a recreation center where I used to play soccer, and I think it came out near Taft junior high school. From what I remember, it was pretty much a straight shot with no branches, but it had a few ladders that went up to storm drains. I think they eventualy put a gate on it so you couldn't go in. Then there was a longer one that had an entrance off of Friars road, and that one was huge.