Try
Google Maps for aerial photography of the site. That should help with the layout of the structure. Also, depending on the time of day the photos were taken and the relative flatness of the surrounding terrain, you can use the relationship of the shadows the structures cast to determine the relative height of each structure element to another.
I use 0.040" thick styrene sheet, available from Evergreen Scale Models, to construct the substrate of the buildings I put together. It's thick enough to be sturdy, but thin enough that it's still easy to work with. And by the time you laminate the outer textured styrene veneer on it, it's bulletproof.
I'd suggest you look at a couple aerial photos, even consult your local property tax appraisal district (an underrated source of mapping) and begin making sketches. Put together some detail sketches of the things you remember best - like piping and valve clusters, safety cages, dust collection systems, loaders, etc. - and try to figure out where they fit into the structure's layout. Then work on the overall layout, thinking about doors, windows, vents, etc. Put together as comprehensive a plan as you can, then determine from that plan what you want to model and what you want to give the illusion that you've modeled.
Break down into rudimentary shapes what it would take to model each component (1-¼" dia. PVC pipe, 0.080" x 0.080" H beams, etc.) and design your "kit." Think in terms of shapes, like 8" x 6" rectangle, 4" tall or 3/4" dia. silo 8" tall. Then buy the components and begin assembling.
It's really not much more difficult than that. It just takes some plastic, practice, patience and perseverance.