Trapped Under the Sea is the most exciting book you'll ever read about a sewage plant. Let me explain.
One day, a colleague of mine was asked to sum up engineering ethics in a single sentence, and he said, "No headlines." When engineering goes right, it's usually not news, unless it's some spectacular success such as a moon landing. The engineering-related events that attract reporters are the ones in which someone gets injured or killed. And that's exactly what attracted Boston Globe reporter Neil Swidey when in July of 1999, two specialist commercial divers died in a nine-mile-long tunnel underneath the Atlantic Ocean as part of an effort to improve the sewage-treatment facilities of the greater Boston area. Ironically, the men died in the process of removing safety devices designed to prevent an unlikely but terrible accident.
For about a century, the sewage of the greater Boston area was dumped with minimal treatment into Boston Harbor, with dire consequences to fishing and public health. The sluggish bureaucracies in Massachusetts finally got coordinated enough in the 1980s to mount a massively expensive plan to build a new state-of-the-art sewage facility on a peninsula called Deer Island. As part of the plan, engineers called for a nine-mile-long tunnel dug through the rock underneath the Atlantic Ocean to take the now-much-cleaner effluent to a series of "diffusers" (sort of like giant water sprinklers) that would discharge it where it would be diluted by ocean currents and dissipate with much less environmental impact.
Digging the tunnel itself was a huge undertaking, and putting the vertical "riser" pipes in place to conduct the effluent up from the main tunnel to the ocean floor without flooding the tunnel was a tricky process as well. The diffusers were plugged when installed so water couldn't get in that way. But in the unlikely event that a stray ship dragged its anchor across a riser and broke one off, the ocean would rush in and flood the tunnel prematurely, killing all the workers inside. So as an added precaution, the contractor installed safety plugs where the risers connected to the main tunnel.
The problem with this was, nobody gave much thought to how they were going to take out the safety plugs once the tunnel was finished. The sensible thing would have been to take them out just before removing all the lighting and air supplies that made it possible to work there without special breathing equipment. But this was not done for various bureaucratic reasons, and so in the late 1990s, the contractor was faced with the problem of how to get those plugs out after all the power and air supplies were removed.
In the absence of incoming surface air, the stale air in the tunnel quickly lost oxygen to rusting metal and organic processes, making it impossible to enter safely without specialized breathing apparatus such as commercial divers use. So it was to a team of divers hastily assembled that the engineering organization turned.
What happened next is a case study in how not to undertake a unique and hazardous specialist operation. All parties relied on a mostly self-trained expert named Harald Grob, who designed a cryogenic-gas setup to supply artificial air through long flexible umbilical tubing to the five workers who would pilot two Humvees, each with its own oxygen supply (one for going out and one for coming back in the narrow confines of the tunnel) and perform the complicated work of removing the safety plugs. What could go wrong?
A lot, as it turns out. The book begins at the worst moment, when one of the divers operating the air-supply system sees that the oxygen level indicated with a crude and inaccurate system has fallen below 9%—the threshold for sustaining life. Two of the divers died, and the other three survived only by quick and ingenious moves to switch to backup air supplies.
Swidey did years of research and interviews with everyone he could talk with as well as obtaining court filings and other documents that laid out the decades-long story. He follows the often tumultuous lives of the five divers as well as the experts, managers, and bureaucrats who get involved both before the misguided effort and in the aftermath, when a much more expensive but safer method of removing the plugs is developed. Taking advantage of the fact that the ill-fated divers removed a few plugs before the tragedy occurred, workers used one of the diffuser pipes to suck air in from the far end, making the entire tunnel habitable enough to remove the remaining plugs, but at an expense of about twenty times more than what the original diver plan cost. The book follows the long legal consequences of the accident, including judgments and fines, but without losing any momentum.
A sewer plant is about the most undramatic infrastructure you can think of. But Swidey has made this story into a thriller that graphically portrays the real dangers and complicated problems that men face in hazardous occupations such as commercial diving. As a detailed case study of how a complicated and unique engineering problem went wrong, it compares favorably with books on the Challenger disaster for detail and interest.
As with many engineering disasters, a combination of factors contributed to the accident: a desire to cut corners to save money, the fact that the project was nearing completion and everyone was impatient to get it finished, and a reluctance to cross a cantankerous and moody expert—Grob—whose rigidity and overconfidence played a big role in the tragedy.
The book is illustrated with helpful and accurate diagrams. Swidey made sure to check his technical statements sufficiently so that I didn't notice any errors along those lines. In addition to presenting an accurate technical picture of what went wrong, Swidey has written a real page-turner that keeps the reader on edge.
Sources: Trapped Under the Sea: One Engineering Marvel, Five Men, and a Disaster Ten Miles Into the Darkness was published in 2014 by Crown Press, and is currently available in paperback.
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