I'm currently working on a run to restore power from an abandoned geothermal powerplant in Pullayup (which has been used as a hideout by several of the nastier kinds ghouls), trying to bring power to a metahuman community. I'd like to find out floorplans for such a powerplant, preferrably a relatively small one. If no floorplans could be found, I'd like to know what kindsw of areas/machines would be found in it.

Perhapse, as a starter you can check out this site: GeoThermal Technologies Program
Doing a Google search for Geothermal Power Plant should help find other example, maybe if you expand your search to Geothermal Power Plant plans or floorplans, that might help narrow down your search...

The best sourceof information I've found so far in this direction is CalEnergy; I'll try to draw up a game map based on it.

Ofcourse, searching for 'Power Plant Plans' might raise a few alarms with various agencies in your federal government. Remember good ADVISE, has never been so important.

Edit: For those who can't decern context without smilies, it's a joke.

Don't have my maps on me at the moment, but generally speaking this would have to be located out towards the extreme Southeast parts of the district, and the Auburn district really makes more sense for actually having geothermal energy to tap. I'll try to give some more specific area locations tonight when I have my sourcebooks.

Cannon (Seattle Sourcebook and New Seattle) has several abandoned geothermal plants in the Hell's Kitchen neighbourhood of Pullayup, established after the 2018 erruption but abandoned in the 2029 Crash. The PCs will be sent clean up the powerplant so that the local squatter-tribe of Ortig (not the neighbourhood, but the small built-up urban part of it, as seen on one of the maps here).

The most likely sections to actually have Geothermal activity are to the south between Orting and Eatonville, though it is possible that some activity may have occured in the Carbon River valley heading east towards Carbonado and Wilkeson. Unfortunately Canon material is pretty inaccurate as far as the supposed Ranier Eruption goes. Any vents in the Puyallup district would have been buried under many meters of lahars and mudflows, on present day Ranier most of the hot springs, vents, etc. are much nearer to the actual summit. Any real viable sources of geothermal energy would be located in Salish Territory. Being a local and actually having studied our volcanoes a bit I tend to disregard Canon material about setting a fair amount (as many people probably do about items set in their home towns that are wildly inaccurate or unlikely) at least where it is in conflict with observable reality or reasonable suspension of disbelief. For example I can reasonably believe the Federal Court House is sold and becomes a club 65 years in the future, I can't believe that a cascade Volcano would suddenly erupt in a manner radically different than what it has done for several previous eruption cycles (even where ritual magic is involved).