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NYC 9/11 Public Portal Document

H COVER STORY P E O P L E

Engineers Shared Danger, Made Difficult Decisions on Safety ■ t is night, on the first week after Sept. 11. Wreckage ■ is everywhere. Twin tower remains groan and teeter, ■ and sometimes, fall. Fire smolders. Danger lurks. Emotions are raw. Exhausted and clinging to thin threads of hope, rescue workers, often on dubious foot­ ing, comb the camage searching for survivors. Along the south side of the site, everyone has cleared out Everyone except two men, who stand alone on the edge of a giant crater, where steel from Two World Trade Center had gouged a 70-ft deep hole in the sev­ en-level basement surrounding the south tower. Loom­ ing overhead is the immediate threat—a 240-ft-tall jagged but upstanding remnant of the tower’s south w^, as tall as most 20-story buildings. Looking back on his single most unsettling experi­ ence since two hijacked planes attacked the twin 110- UNE-UP Lopez, Peraza, Rinaldi, Tamaro and Burton bonded. story towers, structural engineer David B. Peraza says, “There was concern about the wall. Rescuers had heard nois- Peraza’s on-the-spot assessment was that there was reason for es. They wanted engineers to take a look at it.” concern, and the area was kept clear. Whatever happened to Peraza, an LZA/Thornton-Tomasetti vice president, had the leaning wall? “It eventually got pulled down with great dif- been at Ground Zero since Day One, as part of the LZA/TT ficulty,” says Peraza. team providing structural services to New York City’s Dept of CALL TO THE TRENCHES. Fear. “Snap” engineering. Deci­ Design and Construction. “Joe and I got as close as we could,” sions that, if wrong, could have dire consequences. That was says Peraza, referring to Joseph Deluca, DDG’s senior construe- the situation for the advance teams of engineers at Ground don manager. “There we were, two humans on the edge. We Zero, who were dedicated, to the safety of rescue, recovery and stood listening. We would hear a noise. Debris was clinking construction workers. They garnered the respect of contrac- down. ” The dialogue-on-the-precipice went something like this: tors, who sometimes chided—halfjokingly—their document- ‘Did you hear that?” drawing, squeaky clean, risk-averse ways. “Yes.” Not so Pablo Lopez, the Jacques Cousteau at Ground Zero “Are you scared?” for geotechnical engineer Mueser Rutledge Consulting Engi- ( “Yes.” neers, New York City. On Day Five, as DDG’s Executive Deputy With a crater in front of them and a debris field behind, it Commissioner Michael Burton tells it, Lopez emerged from i was clear that even if the wall came toppling down “slowly,” the his team’s explorations down under covered in soot. “Pablo, “ two would not be able to run from it, says Peraza. “So Joe you said you would only go in safe areas!” Burton exclaimed. | turned to me and said, ‘If that starts coming down, line your- But the structural integrity of the slurry wall foundation, £ self up with a window opening.’ I laughed and said, ‘Yeah, and which was keeping the Hudson River at bay, was up in the air. $ turn sideways’ as if that was going to save us. At that moment. Someone had to go inspect. “We inflated rafts and paddled east | we bonded,” says Peraza, of their shared terror. to the PATH station, then south,” says Lopez, making structural | assessments along they way. |

'□(S' ^Jl L As a result of the Mueser Rutledge-led expeditions, George J. Tamaro, a principal of the firm, eventually pronounced the ——r—rr—sluTTy Wall Conditionally stable but supported by compacted S I

? debris in some areas. Tamaro § says each time he issued a con- | elusion about the integrity of I the slurry wall, he would worry, fe “What if I am wrong?” The re- | sponsibUity bears down on him I

J®*' like a huge weight Then, in early October, the south wall, along the crater—a known area of potential insta- bility—did start moving. That § § g g g THREE VOLUNTEERS PLUS ONE SEAoNY’s Mahoney, DePaola, Gllsanz connect with Eschenasy. was the most nerve-wracking |

DECEMBER 17, 2001/ENR 27

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