Smallville Season VI - Episode XIX

Again, Lex is abducted by Ms. Keeman, wife of U.S. Special Force sergeant Wes Keeman, who is reportedly dead, but she believes that Lex is experimenting on him. She rigged the tunnel system with bombs threatening to kill Lex if he doesn't reveal her husband's whereabouts. Clark's attempt to rescue Lex fails since the tunnel is riddled with green Kryptonite. Lex grabs the gun from Ms. Keeman and shoots her before she detonated a C4 in her hand. The tunnel begins to tremble as he and Clark try to escape. Clark loses his power because the presence of the green Kyptonite, and he is buried under the falling concrete.
Lex leaves and comes back with a long rod, moving the concrete away, saving Clark. They barely escape before the tunnel system explodes.