PITTSBURGH, Pa. — Brown silt, illuminated in the ghostly globe of light cast by Paul Warchol's headlamp, glided into the divers mask 2 inches in front of his eyes.
The tether connecting him to the boat above suddenly snagged on something in the black, watery expanse behind him. A moment later, his headlamp cut out. His communication system followed, abandoning him to the hollow, rasping sound of breaths drawn from his air tank.
Alone in the darkness, nearly 18 feet below the Allegheny River's surface, Warchol willed off the clawing panic.
"You've got air. All is well. Just follow the rope back," Warchol said, recounting his first day training in the river with the Pittsburgh River Rescue Unit.
Divers face lethal, unpredictable conditions in one of the region's least-forgiving workplaces. They're called to swim under ice sheets, battle currents as strong as hurricane-force winds and feel their way around obstacles cloaked in blinding clouds of silt.
After the Aug. 1 bridge collapse in Minneapolis, divers picked through mangled wreckage for nearly three weeks, recovering 13 bodies. Pittsburgh's River Rescue Unit long has planned for such a disaster here, said James Holman, the unit's chief.
Warchol, like five others training to join the unit's 18 rescue divers, is a city paramedic. More than 20 city police officers serve alongside the divers, piloting boats, directing divers from the surface and training for counter-terrorism operations.
Many times, the work is recovery, not rescue, said Steve Phillips, 50, of Bethel Park, who helps train recreational divers.
"It's really tough and dangerous work," Phillips said. Often, "they're risking their lives to look for a dead body."
Victims have been revived after more than an hour under water, said John Soderberg, the unit's chief diving instructor and crew chief. After an hour, divers slow their search and take fewer risks.
"I will risk more if I have a lot to gain," Soderberg said. "We shouldn't lose anybody, but you can almost accept somebody dying to save somebody else's life."
'Everything's done by feel'
The unit can "splash" as many as eight divers at once, Holman said. Each is supported by a backup diver and a tender, who talks to the diver through a headset and holds the tether. If the diver gets stuck, his backup can plunge into the water, taking a pack with two air tanks, extra lights, a knife and a small saw.
Entanglements are unavoidable, said Randy Kovatich, 51, a 12-year veteran of the rescue unit. Debris -- downed trees, construction waste and old cars -- littler muddy river bottoms.
Federal Homeland Security grants helped the unit buy sonar to peer through the silt, but divers rarely see what they're looking for.
"Everything's done by feel," Kovatich said.
Vision isn't always a blessing. When a car carrying Betty and Cherise Johnston, a mother and daughter from Swissvale, veered off a North Shore street and plunged into the frigid Ohio River at 10 a.m. Feb. 17, 2006, Soderberg and five other rescue divers followed. They worked in shifts in the 36-degree water, searching until after 2 p.m. for the women, who drowned.
"When we saw them, they were both pressed up against the back window, looking out at us," Soderberg said.
If victims are alive, the unit's two 30-foot Sea Ark boats can provide treatment much like an ambulance, Holman said.
"You go immediately from being a diver in the water to being a medic," Kovatich said.
Voice communication revolutionized rescue diving, Kovatich said. When he started, the diver and tender communicated by tugging the tether -- messages a loose tree branch could mimic or mask.
River currents, jagged debris
"It's kind of scary down there," Kovatich said. "Now, at least you can hear somebody, you can talk to somebody."
Relentless currents also cause problems. Rescue divers don't train if the water is moving faster than 1 mph, which is about the average current speed, Holman said.
"That's the maximum you can swim against for any period of time," Phillips said. Swimming against a 1-mph current, "is like trying to walk against a 30- or 40-mph wind."
Kovatich and others on the team have plunged into rivers moving as fast as 4 mph -- the equivalent of a 120-mph wind. During a flood, the current can flow faster than 5 mph, according to the U.S. Army Corps of Engineers.
Divers must closely watch their depth, Soderberg said. Rising too fast can burst eardrums, cause lungs to explode and create nitrogen bubbles in a diver's bloodstream, Soderberg said.
After a bridge collapse, divers would have to navigate through twisted mounds of steel and jagged concrete fragments. It would be easy to change depth too fast, Soderberg said. He teaches divers to watch their bubbles, to make sure the bubbles are rising faster than they are.
Divers work full time on the river only during summer. Usually, they work from land-based paramedic units, answering calls on land and in the water during the same shift, said Larry James, the unit's senior diver, with 22 years of experience.
"You're in the water, (dodging) concrete bags and spools of cable. Then you come in, get cleaned up, go out and maybe deliver a baby," James said.
Despite the dangers and rigorous training, paramedics said they've waited as long as 15 years to join the rescue team. They're drawn by the thrill of a successful rescue or recovery, and the pride in being part of a team capable of going where few others can, James said.
"There's some great people out here," James said. "They're the reason I don't leave."