National Geographic : 1956 Sep
379 Cavernous Kemano Powerhouse, Carved in a Rock Mountain, Could Embrace a Cathedral To build the world's largest underground power station, miners burrowed a quarter-mile inside Mount DuBose. Solid granite walls help contain the enormous pressure inside the penstocks (opposite) and make the station secure against landslides and air raids. Vaulted and ribbed with concrete, the cave is now 80 feet wide, 135 feet high, and 700 feet long. Four giant generators produce power for Kitimat's sea-level smelter. Construction equipment still cluttered the room when the overhead crane lowered this generator rotor into position.