Officials Fear Oil May Have Seeped Into Sand : Pollution: Tests are being conducted to see if crude soaked beneath shore. Reopening of Orange County beaches may be further delayed.

Just when it appeared that efforts to mop up the Orange County oil spill were winding down, authorities expressed fears Wednesday that a thin vein of crude may have seeped into the sand along a broad stretch of shoreline, threatening to further delay the opening of beaches.

If tests find oil lurking in more than a few isolated pockets in Huntington Beach and Newport Beach, officials said they might be forced to call in heavy equipment to tackle the oil-tainted sand.

Authorities speculated that heavy rain and pounding waves from the fierce storm that lashed the Southland last weekend may have driven oil as much as a foot into the sand in spots most heavily hit by the Feb. 7 spill.

“I suspect this will delay the opening of the beaches,” said Petty Officer Tim Rowe of the U.S. Coast Guard. “The beaches look very good on the surface. But right now we have to figure out what to do with the stuff underneath.”

Work crews Wednesday began taking samples along six miles of coastline stretching from Huntington Beach Pier through the Newport Pier, with results expected early today.

Officials with British Petroleum, the firm that owned the 394,000 gallons of Alaskan crude that was spilled when the tanker American Trader punctured its hull with its own anchor, said workers were digging into the sand at various points along the shoreline to determine the extent of the spread.

The state Department of Fish and Game will review the findings and decide how to tackle the problem after consulting with representatives of local cities, the Coast Guard and the oil firm, officials said.

Among the options being weighed by officials are using a tractor and disc to plow up the crude so it can be removed by work crews. Another possibility, according to a British Petroleum spokesman, would be to employ a device that can sift through the sand and cleanse it of oil. But authorities appeared to have ruled out employing bulldozers to dig up sections of beach and cart it off.

A British Petroleum spokesman said the extent of beach affected by the layer of oil is not clear. “The last thing we want to see are the beaches reopened, kids out there playing with sandcastles and coming across oil,” said Chuck Webster, crisis manger for the oil firm.

Some local city officials, meanwhile, were calling on British Petroleum to conduct toxicity tests to ensure that the beach will be safe when the weather turns warm and the crowds begin to hit the sand.

“I want to have chemical analysis done every quarter or half-mile to see if there’s any contamination,” Huntington Beach Mayor Thomas J. Mays said. “When I open that beach, I want to make sure it’s safe for people to walk on.”

Other officials said they were pleased that British Petroleum was making efforts to unearth any oil that may have percolated into the sand.

Times staff writers Lanie Jones and Dan Weikel contributed to this story.