The stack, constructed in 1908, is now approximately one foot off its centerline and officials fear what could happen if another quake hit. While the main steam plant did not sustain damage in the quake, a Seattle engineer said the 85-foot stack would not have lasted another 15 minutes during the recent shaker.

The stack, once used to discharge byproducts from coal boilers, now releases steam generated by natural-gas heat from the plant. The Pioneer Square Preservation Board indicated that any rehabilitation must meet standards established by the Secretary of the Interior and the local Preservation District.

A new tower would entail significant work on the main plant. The stack extends through the entire six floors of the main facility and reconstruction would be costly and complex.