Books: What 'Trapped Under the Sea' Teaches About Safety
Readers love a rescue drama and Neil Swidey’s new book, "Trapped Under the Sea" (Crown, $26), is an unforgettable review of how the final stages of the cleanup of Boston Harbor in 1999 turned into a disaster that killed two divers. It's also a warning about the dangers of "go fever," the tendency to rush a project to completion while overlooking potential dangers. The words suggest an overheated devotion to getting things done and getting paid.
The space flight disasters Challenger and Discovery brought "go fever" into public conversation. It is an everyday issue in construction, especially now that we have many larger and more complex projects that, while never reaching the complexity of space travel, extend far beyond routine work and deploy thousands of workers.
In the case of the Boston Harbor cleanup, "go fever" produced a crazy plan for sending divers down an airless, tapering, 9.5-mile-long outfall tunnel for the Deer Island sewage treatment plant—the critical element in a state-of-the-art engineering plan to finally rid the harbor of its infamous dirty water from years of untreated sewage pouring in. The divers' job was to remove plugs from diffuser risers to allow treated sewage to flow out far out in the harbor, while using a jerry-rigged air supply in the shaft.
A decade before the fatal work in the tunnel, engineer Metcalf & Eddy, charged with producing a conceptual design, had first considered a design for a tunnel from Deer Island, where the Massachusetts Water Resource Authority had built sewage treatment facilities. The tunnel design included diffuser risers, extending from the main shaft, through which the sewage would be discharged.
During construction, the risers would have to be plugged and Metcalf & Eddy weighed plugging from inside or outside the shaft. The firm stated that removing the plugs from inside the unventilated shaft, after the ventilation system used during construction had been removed, was too difficult. Plugs from on top, though more costly than plugging from inside, would be cheaper.
The issue was left there until the tunnel was subsequently designed in greater detail by engineer Parsons Brinckerhoff with inside plugs. PB also rejected the idea of keeping the main construction ventilation system for plug removal, judging that it was safer if workers spent less time in the tunnel.
Moment of Reckoning
How to remove inside plugs in the riser ends had never been conclusively decided. With the completion of the risers in 1997, the prime construction contractor, Kiewit, arrived at a “moment of reckoning,” in Swidey’s words, about how it was going to do that job.
Kiewit's contract, signed in 1990, specifically required it to specify how to ventilate the shaft during plug removal. Kiewit later complained about the dangers in this part of its job, Swidey reports, but the other project members pointed out that it was Kiewit's duty to figure it out.
"In truth," wrote Swidey, "during the early years of the project, they barely thought about the plugs at all.”
During 1998, when key decisions about the riser plugs had to be made, Kiewit and the MWRA and engineers sparred regularly about disputed payments. Out of $156 million in claims filed by Kiewit, $120 million or so were pending at that time.
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Casting about for solutions to the plug-removal dilemma, Kiewit turned to two specialty diving firms, Black Dog and Norwesco, and designated Norwesco as the senior partner in the venture partly because of the impressive solution supplied by one of its principals, Canadian engineer Harald Grob. Kiewit also made Black Dog the junior partner because Black Dog was too small to obtain a surety bond.
When Black Dog's principals saw the design for temporarily supplying air to the divers far down the dark tunnel, they were amazed—dazzled is how Swidey puts it—by the inventiveness.
Grob had determined that instead of trying to transport bottled air over so great a distance, there would be three sources: high-pressure compressed air, rebreathers to serve as backups and an unusual mixing system that would combine liquid oxygen and liquid nitrogen in the tunnel to produce air. The liquid gas was lighter than any other portable breathing system option.
Equipment Unavailable
The trouble started when the equipment needed to realize Grob's apparent cutting-edge mixing system was unavailable up to a month before the planned unplugging mission. After rummaging around the Internet to find the equipment, Grob, in Swidey’s account, didn't tell the divers about that and other problems in putting the system together.
After running a test mission that made some of the divers uneasy, a crane lowered the five divers into the tunnel on July 21, 1999. They took their places in Humvees linked to wagons carrying breathing equipment and tools, and set off into the darkness.