Preparation of Hollander Ridge Tower for Implosion


The Building:

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The view from 62nd Street towards the front of the building shos the true enormity of the structure. This 20-story high building, known as Hollander Ridge Tower, was built in 1976. Its construction was so strong that 24 years later, there were still no cracks in the concrete floors or support columns. The small lowrise building to the left will be demolished after the implosion. This view, looking south, shows the proximity of the rear wing to the access road. Across the road are single family homes, which must be protected from harm during the implosion. To do this, the building will fall towards the west, down the hillside, and safely away from the vulnerable houses.

Please be patient while photo loads. Nestled into the hillside, the tower gives the illusion of being somewhat squat. The view from the roof gives a better sense of the true height of the building. This view looking down, and shows the front courtyard, into which most of the debris will fall.

Along the left side of the photo, you can see walls knocked out on several floors. These are the floors where the explosive charges will be placed. At the base of the concrete wall on the right, you can see large holes where the concrete has been removed from the shear walls to help weaken the building.

The heavy mechanical equipment on the roof will not be removed for the blast. It will fall to the ground with the rest of the building, and the metal salvaged for recycling later on. Most everything in the building - metal, concrete and brick - will be recycled in some form.

A camera has been placed in this vicinity on the roof, and will record some spectacular images as the building crashes to the ground. (Stay tuned, as we will link to that site when it becomes available.) It is facing the northwest corner, which will be the first section to fall. It will be followed by the northeast corner, then the southern wing, which is where this photo was taken from.
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The Challenges:

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As a whole, Hollander Ridge Tower sits by itself with very little surrounding it. The former neighborhood, which consisted of 92 lowrise apartment buildings and the tower, has already been reduced to rubble. The only vulnerable structures are a neighborhood of homes to the eastern site of the building. Every precaution will be taken to ensure they are not harmed in the implosion. This view is looking south, with Interstate 95 along the righthand side of the photo. 62nd Street parallels the highway, and is where our photos were taken. The white circle indicates the spot 1,000 feet away where our camera was set up.

Preparation for Destruction:

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A lot of work goes into the building before the first explosive charge can be placed. Interior walls, ceilings, doors and such are stripped from the building until nothing remains but the superstructure. This is then carefully attacked to weaken the building in key locations. The exterior walls are stripped from the first 3 floors as well as the 8th, 12th & 17th floors. These five floors are the ones that will receive the explosive charges.

Taking out the first 3 floors are the most critical in getting the building to collapse. The charges placed on the upper floors help control the direction and break up the debris for easier removal from the site.
Many highrise buildings are constructed of curtain wall on the exterior. These walls do not take any of the load required to keep the building standing. This tower was different though. The exterior concrete shear walls were built strong, and would take extra effort to demolish.

Large gaping holes were cut into them before the blast to ensure they collapsed as planned. Dynamite will be loaded into the columns that are set within the shear wall.

Please be patient while photo loads. With the building sufficiently stripped and pre-weakened, the drilling of the holes for the explosives begins. Heavy equipment is brought in to bore through the solid concrete columns. Placement of these holes is critical, as the charges must be precisely placed to ensure a successful implosion.

Some sections of shear wall can not be removed ahead of time, as they must support the building while the preparation work is being done. Many holes will be drilled into the shear wall, so it can be properly destroyed in the implosion. Please be patient while photo loads.

Please be patient while photo loads. Implosions must be planned carefully, since there is no second chance to get it right. To ensure success, the blaster does a "test shot" on several columns using varying amounts of explosives. The intent is to find the smallest amount that is enough to blow up the concrete surrounding the rebar, while minimizing flying debris.

This test shot was done on July 5, 2000, just 3 days before the actual implosion. The concrete has been successfully destroyed, while leaving the exposed rebar slightly bowed under the weight of the floor above. The amount of explosives that produced this desired result, will tell the blaster how much he has to load into the rest of the columns.

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Now that the blaster knows how much explosives to use, the demolition team will go through the building and load each hole with dynamite or a similar explosive charge. Each charge is then hooked up to a blasting cap and carefully wired to all the other charges. Delays are built into the wiring system to control the timing of each detonation. These delays will control the direction and rate of collapse of various parts of the building. After all the explosives and wiring are in place, the final step is to wrap each column with a heavy geotextile fabric. This fabric will keep flying debris to a minimum. This is necessary to ensure that other nearby charges are not harmed, and that flying debris does not reach the nearby homes that are being protected.

Phillyblast would like to thank Dave Hersey of Dykon for the photos used on this page.



Created: July 11, 2000
Last Modified: July 16, 2000