In 1900 Philadelphia, then the third-largest city in the U. S. with a population of over one million, was a bustling metropolis whose downtown streets were lined with three-and four-story department stores and other structures, such as the four-story brick edifice built by some enterprising Philadelphians at 2136-2138 Market, near the corner of 22nd and Market Streets.
Over the years, the building saw a variety of uses. Its facade was modernized, but its basic construction of brick augmented with steel beams remained unchanged. Finally, in May of 2013, the current owners of the structure decided to take it down. And here is where the building entered the annals of engineering-ethics tragedies.
The safest way to take down a brick building is by reversing the way it was constructed: that is, brick by brick. Such an approach is prohibitively expensive, so demolition firms use more efficient methods, such as wrecking balls and hydraulic excavators (a type of heavy machinery with a long hydraulically operated arm and a scoop at the end). The problem with brick walls and demolition operations is that the walls have almost no tensile strength on their own, if they are unsupported by an all-steel framework or facade.
While properly built brick buildings can reach heights of fifty feet or more and last for thousands of years, any substantial sideways force on the structure cracks the mortared joints between the bricks and turns the thing into a big pile of loose bricks, which do unpredictable things. This is why Sean Benschop, the man operating the hydraulic excavator at the Market Street demolition site, was taking a huge risk as he worked to take down the remaining parts of the 113-year-old structure he was hired to demolish.
While demolition operations fall under the purview of the City of Philadelphia’s building inspectors, and a permit was required to begin the demolition, no inspections were carried out during the demolition itself. If a city inspector had happened by on Sunday, June 2, he might have seen what a passerby videoed that afternoon and subsequently posted on YouTube.
The four-story building in question faced the street, and to its immediate right as you faced its front was a one-story Salvation Army thrift store on the corner of 22nd and Market. Both buildings were long and narrow and extended parallel to each other about half a block to the rear. On that Sunday afternoon, someone (presumably Mr. Benschop) had moved his hydraulic excavator onto the sidewalk in front of the thrift store, and was going after the remnants of the front wall, which was about two stories high at that point. An assistant played a spray of water on the wall, presumably to keep down dust. But the video clearly shows bricks falling from the front wall onto the sidewalk, which is apparently open to anyone who would be foolish enough to approach the scene and risk getting hit by falling bricks. No one had erected the open plywood-box type of shelter for sidewalks that is customary at constructions sites that border the street. Even more ominous in this scene is the right-hand side wall of the old building, which has been partly removed near the front but looms near its full original height toward the back, rising above the one-story Salvation Army store.