(Recasts lede, adds mine official, miner relative quotes)

By James Nelson

HUNTINGTON, Utah, Aug 11 (Reuters) - Six trapped coal miners failed to respond to rescuers pounding on a second drill that has penetrated a collapsed Utah mine, but there was a "survivable space" and safe drinking water, officials said on Saturday.

Water pouring through the drill hole foiled an initial attempt to use a camera to examine the space. Rescuers plan to insert a lining in the hole, which will take many hours but will protect the camera and let it send back images.

The miners have not been heard from since Monday, when part of the Crandall Canyon Mine near Huntington, Utah, collapsed.

There is potable water and a nearly human-height void where the second, nearly 9-inch (23-cm) drill punched through the mine ceiling, U.S. Mine Safety and Health Administration chief Richard Stickler said at a news conference.

Rescuers hope the reinserted camera will be able to scan 100 feet (30 metres) in each direction and provide details of the conditions underground.

After the second drill broke through the ceiling of the mine in the middle of the night, rescuers banged on the metal drill a series of three-rap signals to draw the attention of any survivors, shutting down all the equipment and lights on the surface to listen for sounds from below.

"Unfortunately we did not get any response," Stickler said. However, a space 5-1/2 feet (1.7 metres) high, with another 2 feet (0.7 metre) of broken coal and water, left room for hope.

"We found survivable space," he said.

A first, 2-1/2-inch (6-cm) drill pierced into another area of the mine late on Thursday. There was no sign of life when a two-way microphone was lowered into the mine, and tests in that hole showed that oxygen levels in the chamber were too low to sustain life.

DAYS OF DIGGING

"We wait. We wait and pray," said Tomas Hernandez. He said his nephew Luis Alonso Hernandez was one of the trapped miners.

The mines have been sources of work for immigrants for more than a century. Three of the trapped miners are Hispanics, although officials have not given their names.

"Many Mexicans, maybe, will go back to Mexico, scared," Hernandez said in an interview.

It will take crews digging horizontally days to create an opening large enough to pull the miners out. Mine co-owner Robert Murray said he was very disappointed at the pace of that effort.

"The mountain itself, the tectonic forces in the mountain, continually cause us some concern," he said at the news conference.

Horizontal digging had advanced 650 feet (200 meters) and the crews had about 1,300 feet (400 meters) to go. But the mine's roof needed to be shored up frequently to prevent collapse.

Officials have said the men could possibly survive for weeks in an underground chamber. The larger drill hole could be used to provide food, water and air until they were rescued.

Murray has insisted that an earthquake triggered the collapse. But geologists say the shaking recorded by their instruments was caused by the cave-in.

Controversy has also risen over reports that the miners were engaged in dangerous "retreat mining" when the shaft collapsed. Murray has denied such a technique was being used.

Retreat mining involves supporting a mine's roof with a column of coal, then removing those pillars and allowing the shaft to collapse as miners move to safety.

The Crandall Canyon Mine is on a high desert plateau some 140 miles (225 km) south of Salt Lake City, in what is known as Utah's "castle country" because of the towering rock spires that dot the rugged landscape.

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