At the base of the shaft, and for the tunnel’s first several miles, there would be sufficient oxygen in the ambient air for the Humvees to start. But as soon as the oxygen content in the tunnel air slipped to below 16 percent, the engines would likely stall146. To get over that hurdle, Harald had turned to two different Spokane companies, Nex-Gen Manufacturing & Controls and K&N Electric Motors. They devised a sophisticated air system, which involved a liquid oxygen tank mounted on the back of each Humvee, along with a scrubber added to its exhaust pipe. Attached to the oxygen tank was a tall, sleek device of black metal that looked like an upright radiator in a trendy condo. This heat exchanger/vaporizer would augment the conversion of the liquid oxygen into a gaseous state and help ensure that the resulting gas remained at the correct temperatures and flow levels in order to feed the internal combustion engine of the Humvee. This heat exchange process was critical, since the liquid gas was extremely cold. Not for nothing do dermatologists turn to liquid nitrogen to freeze warts off their patients’ skin. The extreme cold slows down the molecules of the nitrogen or oxygen, allowing them to be packed in more tightly.
Governing this whole vehicle-air-supply setup was a separate device called an oxygen-injection control. It would monitor the oxygen content of the air going into the engine, automatically making any necessary adjustments.
In contrast, the system that would provide the divers with breathing air looked fairly improvised. The liquid oxygen and nitrogen cylinders sat in their rack on the trailer and would connect via a half-inch-wide hose to the MAP Mix 9000, whenever that mysterious machine finally arrived from Denmark. The mixer would be placed in the back seat of one of the Humvees. Once it did its work, the blended gas would be sent out through a separate hose connected to a distribution manifold inside the vehicle. In reality, that manifold was little more than a piece of roughly cut, unpainted plywood147. With hose inputs mounted onto it and fortified with lots of duct tape, the plywood manifold would be placed at an angle between the Humvee’s bucket front seats. It would connect by hose to a second plywood manifold bolted to the outside of the Humvee, which would connect, through twelve hundred feet of narrower hose, to the flat-bottomed boat used by the three divers journeying on foot to the end of the tunnel. Those divers would each have an additional three-hundred-foot umbilical connecting them to the boat.
So all five divers would be relying on the same mixed-gas breathing system for the air they needed to survive. The only difference would be the length of their umbilicals. The three divers working at the end of the tunnel would be connected to the breathing system by fifteen hundred feet of hose. The two divers remaining in the Humvee would be connected by just ten feet.
Wednesday brought with it yet another problem involving the trailer, even after the hitch assembly had been repaired. Of course, because the tunnel would eventually become too narrow for the divers to turn their vehicle around, they needed the trailer so that the lead Humvee could tow the second Hummer, which would be facing in the opposite direction for the drive home. But the crews noticed that once the bigger Humvee had been backed onto the trailer, the weight had pushed a couple of the trailer tires down into the gaps between the slats of the aluminum deck. And now those tires were flat148. After changing them, the crew realized that they would likely get a repeat of the flats if they tried again to load the Humvee wagon onto the trailer while it was on the deck. So reluctantly they decided they would have to wait until both Humvees were off the deck before trying to back the bigger of the two onto the trailer. And that would require a particularly tricky maneuver, given all the standing water below the deck. At least they wouldn’t have to worry about it until the next morning.
Despite this latest setback, these first few days in the tunnel gave Riggs a better feel for the Black Dog crew. Billy struck him as both energetic and knowledgeable, a real pro with a steady hand—and apparently a big appetite for a little guy, given the size of the cooler he packed his lunch into every day. Most surprising, Riggs had even found himself beginning to warm to DJ. Back in New Hampshire, he had seen DJ as a guy who tried to skate by and seemed most interested in extracurricular action. But once they began working in the tunnel, Riggs was pleased to see that DJ was all business.
Through the Humvee’s rearview mirror, DJ could see Billy, standing in knee-deep water, giving him hand signals. Go, but go slow. DJ knew his assignment on this Thursday morning was precarious, especially given all the trouble they’d had with the first Humvee. Although the temporary deck they’d been working on at the base of the shaft was wide enough to fit two Hummers side by side, there was only a single-lane ramp leading from the deck down to the water-soaked tunnel floor. The ramp was scarcely an inch or two wider than the Humvee itself, and it was extremely steep. DJ had to back the gray Humvee149—its cab and roof rack groaning with gear—down the sharp decline of the ramp. Hoss had already backed down the white Humvee, and it had gotten stuck along the way. It had remained stuck until Billy thought to wedge a two-by-six plank of wood underneath the Humvee’s back wheels. All this drama, DJ thought, just to get the Humvees in position to begin the journey. What’s more, the divers had to work in front of an audience that included sandhogs, Kiewit officials, and Dave Corkum. Still, as white-knuckle a task as it was, DJ got a jolt out of being behind the wheel of this powerful machine. He was, after all, a guy who could remember the dates of important events in his life according to which muscled pickup truck he was driving at the time.
Having learned from Hoss’s experience, DJ managed to back his Humvee down the ramp on his first attempt. But that turned out to be the easy part. Now, with his vehicle idling in the standing water, he needed to back it up onto the two-way trailer that was already attached to the white Humvee.
The white, eastward-facing Humvee would be the divers’ lead vehicle for the journey. Once they had traveled to the point in the narrowing tunnel where the Humvee could go no farther, they would unload the westward-facing gray Hummer off the trailer, positioning it for the drive back to the shaft. Because the trailer had mini ramps on either end of it, the divers could then back the white Humvee up onto it, converting that Hummer from transportation to cargo for the return trip. So this maneuver at the start of the tunnel was also a preview of the vehicular choreography to come.
DJ’s task in backing the gray Humvee up onto the trailer was made more difficult by how crowded the trailer already was. At its far end, closest to the hitch with the white Hummer, stood the tall cagelike rack holding four 180-liter tanks—three silver ones containing the liquid nitrogen, and one white one containing the liquid oxygen. At the other end lay the greenish flat-bottomed boat, which was brimming with coils of yellow hose but just low enough to the ground to fit under the high-riding towed Humvee. In one corner of the boat, someone had left a sixteen-ounce bottle of Coke standing up. DJ would have to position his Hummer perfectly in order to begin backing it up onto the mini ramp at the end of the trailer. Then he’d have to keep moving in reverse so that the high-riding Humvee backed up over the boat. He had to be mindful of the big cylinder of liquid oxygen that was mounted to the back of his Humvee, supporting its diesel engine. Because space was at such a premium on the trailer, he had to back up the vehicle until it all but brushed up against the cagelike gas rack, but not so much that it actually collided with those four big cylinders inside it. After all, there was a reason “Mr. Science” used liquid nitrogen for his dramatic mist-filled demonstrations on TV, and liquid oxygen, under pressure and highly flammable, could explode if improperly handled. DJ had no interest in putting on a fireworks show.
146 (Chapter 7, note 14)
the engines would likely stalclass="underline" Curt Ahonen (mine safety trainer), interview by author, 2012; Georgia Institute of Technology, Health and Safety Office, “Fire Safety,” www.ehs.gatech.edu/fire/.
147 (Chapter 7, note 15)
roughly cut, unpainted plywood: I observed video and photographic footage of the setup, taken inside the tunnel during the plug-pulling operation.
148 (Chapter 7, note 16)
now those tires were flat: Corry day planner; Grob topside log, July 14, 1999.
149 (Chapter 7, note 17)
DJ had to back the gray Humvee: I observed this scene from a video recording.