Sitka Pulp Mill

This large pulp mill has been mostly torn down by now, Security was quite high before and during demolition, the complex and surrounding properties were frequently used for parties by local teens, and security was quick to challenge any unknown visitor. Today most of the large structures have been torn down and replaced with small industries such as a water bottling plant. Several medium size drains and a large toxic waste dump pipe are still under the complex, The largest drain is easily accessible, but not very interesting. It may intertie with the waste pipe where they pass across eachother, but I doubt it.
Skip to water treatment plant (new)

This older photo shows more of the mill, when in operation it had its own railway with a car yard and rail barge dock,
as well as several silos and large tanks. Now all that's left are the low warehouses on the waterfront and the concrete
structure in the foreground of this picture (the water treatment plant)
Medium Size image (20k)

A bird's eye view of the plant in operation (note the large cargo ship docked at the warehouse)

A map of the mill complex when it was operating. The water
treatment plant is at the upper left. Colored lines show tunnels.
I've explored the yellow one to just past the manhole, pictures are shown below:

Two pics of the drain: It's about 5' diameter and past the manhole the bottom
foot or so is filled with gravel and rocks, making it very uncomfortable to explore.

The Water Treatment Plant:

Formerly this supplied treated water to the mill and to Sitka, now the city has a smaller plant just down the hill from this one. Water is supplied by a pipe tapping the primary water tunnel which runs from green lake to the hydropower plant (also nearby). This facility consists mostly of large concrete mixing/storage tanks, two outside and one underground (beneath the brown building in the first photo). There are also valve systems and control rooms, and some utility tunnels as seen in the last photo. The large white building is fairly well secured, although catwalks lead to its roof and there appear to be tunnels or overflow pipes leading into the basement. The complex is also infested with rats, rustlings in the insulation greet tunnel explorers and discarded and broken traps are scattered about everywhere.

More info (propaganda) can be found here.