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'A Strong Building'
Bldg. 20 Yields to Wrecker's Ball

By Rich McManus

On the Front Page...

In the end, it was a tough old stalwart that didn't go down without a fight.


The blows from a 2-ton "headache ball" rained with the frequency of a fighter's fists on Apartment Bldg. 20 in a carefully controlled demolition that marked the end of the 44-year-old structure's life on campus. When the site is finally bulldozed and leveled, it will become a placid courtyard just a quick uppercut west of the new Clinical Research Center.

"It's a strong building," said Barney Silver, overseeing the demolition as vice president for construction at Boston Properties, the site's developer. "Structurally, it's a very sound building."

As he spoke, the pear-shaped wrecking ball was whanging away at the west stair tower, swinging through nearby tree tops as it gathered momentum. "That stair tower has a 'sheer wall,'" explained Silver. "It's basically poured-in-place concrete. It's hard to bring down. It's taken a lot of work."

The demolition job began subtly in October when crews from contractor EnviroServe, and its subcontractor DMI, began removing asbestos from the interior of the building. The job was slowed when workers discovered more asbestos than they had anticipated. "That was unforeseen, and took almost another month to remove," commented Jeff Bryson, project manager for McCarthy Co., the principal CRC construction contractor. "The unexpected asbestos was found in plumbing risers inside the walls," said Silver.

Also slowing progress was a 2-week inventory of plumbing fixtures served by the Washington Suburban Sanitary Commission that connected to Bldg. 20.

A small bulldozer called a Bobcat pokes through a second-floor window of 20, sending the frame tumbling, during interior demolition of the building.

The next phase was interior demolition -- knocking down all of the inside walls. Workmen lifted Bobcats -- miniature bulldozers -- onto each of the seven floors, and they cleared away walls and doors, pushing the debris out holes poked in the side of 20. This left only the shell and frame.

A single operator using an 85-ton mobile crane parked just out of harm's way methodically undid what it took 14 months to build back in 1952-1953, razing the 67,000-square-foot structure with a deft combination of free swings, devastating drops, and delicate nudges, the most incidental of which sent masonry cascading to a deepening pile at the building's base.

Going, going...:
The gaping square holes on the first few floors of the building were exit points for debris pushed out of the structure by roving Bobcats, which are miniature bulldozers.

"All of that rubble can be recycled, which is cheaper than taking it to the dump," said Bryson. "A drum roller crushes the brick, which can be reused as fill material, or as backfill around buildings."

Noting the thick tangle of steel rebar protruding like al dente pasta from the building's gashed sides, Bryson said, "Bldg. 20 is very heavily reinforced -- more than you'd normally see in a building like that." "The structure is obviously overdesigned," noted CRC project director Yong-Duk Chyun, "and there are a lot more reinforcing bars than anticipated."

A groundskeeper and two "spotters" pause on a rainy December day to watch the wrecking ball at work.

A firehose mounted on the building's top floor gushed water over the headache ball's work, to limit emissions of dust. Occasionally, the ball would glisten blackly with water as it bashed near the hose; other times it was rouged with brick dust or powdered with pulverized concrete, depending on its target at the moment. The big ball was rarely idle and proved fascinating for many passersby to watch. Like a golfer slowly addressing the ball before driving a tee shot, the operator carefully placed the ball on-target before swinging the crane back for the take-away. The approach of the ball toward its target seemed to slow time itself, and hush the singing cables of the crane until the sound of impact -- a dull thud if it met masonry, a muffled crump if beating in the roof.

"He's methodically chipping away from the top down," said Bryson. "The pieces have to be small enough to take away with a dump truck."

The west wall of the apartment house (left) was a poured-in-place concrete "sheer" wall, which withstood many a blow from the ball before yielding. At right, only the lobby and a stub of elevator shaft remain late in the game.

Hard-hatted spotters arranged around the perimeter of the site kept an eye out for flying debris, warning pedestrians if they got too close. "We took care to get a good operator, because we're dead serious about safety on this job," said Bryson. "We're concerned about the swinging of the ball -- we try to keep all swings into the building. We'll be glad when it's gone."

The demolition of Bldg. 20 technically includes the razing of the Wilson Estate property, too. All of the structures but Bldg. 15A had been removed by the first week in January; 15A has been spared only because the contractor uses it as an assembly point for his crew every morning.

"Those are pretty tough old structures," noted Bryson. "It took over a week to pull those down."

Bldg. 20 will be flattened down to its single basement level; only the caissons will be left in the earth.

"The basement slab, the grade beams, the pile caps, the foundation walls -- all of that will go," said Bryson. "But it would be very expensive to remove the caissons. They go down another 30 feet or so. Then we'll backfill the site to the grade of the surrounding hillside."

Preliminary plans call for a children's playground on the old Bldg. 20 footprint. A fitting memorial for a family habitation.

Gone: All that remains is a hill of rubble for power shovels to cart away from the site of Bldg. 20.

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