The tanker "ran soft aground," or lightly scraped the muddy bottom of the channel off the Rodeo coast around 5 a.m. Friday, and two U.S. Coast Guard crews and a helicopter responded, Coast Guard Petty Officer Pamela Manns said.
The chafe did not appear to cause any pollutants to leak in the Bay or any damage to the tanker itself, but the Coast Guard will not allow it to set sail again until an inspector from Los Angeles gives it the go-ahead, Coast Guard Lt. Lauren Kolumbic said.
"We write down something on our form that says, 'until you verify that this vessel is safe you can't leave because we don't want you sailing out of here and sinking'," Kolumbic said.
The inspector could take days to make sure the vessel at Anchorage 9 is secure to leave because he or she might have to perform many tests, such as getting divers in the water to check the exterior.
"It's not like they can come out and test the oily water separator and say 'ok, it's fine'," Kolumbic said. "They can't leave Anchorage 9 until it is confirmed to be safe."
She said the bottom line is there is no evidence of pollution and the Coast Guard responded quickly to the possibility of the problem.
It could take weeks before the Coast Guard determines what caused the graze, she said.