Shell Oil company is complying with California State Regulator's recommendation to replace 19 km of the 285 km long San Pablo Bay pipeline after two spills contaminated grasslands close to San Francisco with 60,000 gallons of heavy crude oil.

Investigators found both were caused by “fatigue cracks” that grew as pressure on the underground line fluctuated to deal with different grades of oil, according to documents obtained by KQED, a local television news network.

Oil from the first spill seeped 10 feet into the ground. Crude from the second incident was discovered as much as 20 feet beneath the surface, according to the Central Valley Regional Water Quality Control Board. The water agency oversaw the cleanups, which involved removing nearly 16,000 tons of contaminated soil and dumping it in an Altamont Pass landfill.

The irony is that Shell inspected this pipeline just months before it ruptured. Now the state is requesting that Shell review all of its pipelines that switch bvetween different pressure levels. Environmental groups are also asking for stiff financial penalties to be imposed on Shell.