The leak appeared to be from a section of piping at the station that is encased in concrete.

WSJ: BP to Cut Oil Production on Alaska's North Slope

In addition, rebar casing was punched 165 feet into the bedrock and encased in concrete, and 18 caissons and 54 piles were also utilized to provide stability to the building.

FORBES: Connect

After the 1986 Chernobyl accident, the world's worst to date, the Soviet Union encased the plant's damaged reactor in a massive concrete sarcophagus.

CNN: STORY HIGHLIGHTS