Wed 31 May 2006
Here (Finally!) is the technical - archaeological second part to a two-part story about the 1945 escape tunnel at the Eastern States Penitentiary. Please read Part I to hear the background of how this tunnel came to be.
The Archaeology of the 1945 Escape Tunnel
60 after the inmates were captured attempting to escape, the archaeological story starts. The task was to find the entrance and exit of the tunnel and then find out if the tunnel is still intact or has collapsed with age. The first phase was the excavation of the tunnel’s ends. With the aid of escape day photographs, it was relatively easy for the archaeologists to find the exact spot from which the prisoners escaped. Excavations were carried out, the backfilled escape hole was found, and a number of artifacts were recovered the dated to the period of the escape. Only a few feet of the exit hole were excavated. On the inside of the prison, in cell #68, heavy handed techniques were used to reopen the location where Kliney began his work. After the escape, the prison filled this cavity with large blocks of schist and concrete. The archaeologist’s excavation could only dent this barrier. With the ends of the tunnel found, it was now time to find the tunnel itself.
The first step in this process was to employ a Ground Penetrating Radar (GPR) unit to non-invasiv
ely probe the sediment below to look for signs of collapsed strata or a telltale void. Stating close to cell #68, the initial results gave the impression of a “V” shaped infilled trench under the courtyard. Possibly this could be part of the brick sewer or it could be the collapsed tunnel. Moving further towards the prison wall, the “V” shaped trench gave way to a very indistinct refraction signal which only showed the faintest shimmer of a hollow cavity. Due to the nature of the iron rich, intermittent sandy/clayey sand sediment below, the feedback from the GPR was diffuse. The locations of possible tunnel sightings were flagged and the survey was concluded, inconclusively.
With a 12” concrete saw, two 2’x2’ blocks of concrete were removed to expose to top of the soil. Closer to the cell, the first of two auger holes (4” diameter) was excavated. From contemporary reports, it was known that the tunnel should be about 10-12’ below the surface. With an auger hole 15’ below the surface and a continuous profile of fill, the hole was abandoned. Either this hole missed the mark or the tunnel was collapsed in this area.
The second auger hole, 10’ closer to the prison wall, was noticeably different form the start. The sediment being augured was much cleaner and sandier than previously, worked progressed quickly. At 8.5’ below the surface, the auger was set back into position to take another 10” deep sample when all of a sudden, “Thump”, the auger dropped. Falling nearly to the handle, the auger had found its mark.
In order to verify, and hopefully inspect, the tunnel, special video equipment was needed. The first attempt at seeing in the tunnel was done through the use of an “Electric Eel” sewer camera. This piece of equipment consists of a LED lit camera head on the end of a semi-rigid cord hooked into a small close caption display and VCR. The initial results were low quality, but stunning none-the-less. After 60 years, the tunnel from which 11 men tried to gain their freedom was seen again. As the camera was pushed through the soft sediment, only glimpses of the tunnel environment were seen. After some exploration, the camera, sprung by the tension of its own cord, flashed from darkness to the view that everyone had been waiting for; a clear picture of the wooden braces used for shoring. This “artifact” was one of the two key pieces to telling the tunnels story. Aside form the once rumored wooden supports was a description of an electrical lighting system used by the inmates. No evidence of this could be seen in the sewer cameras images.
The second attempt, some months later, to get a clear picture of the tunnel utilized much more advanced
video equipment. Thanks to the very accommodating team from EnviroSight, the second phase of tunnel video was an unqualified success. Using two pieces of equipment, a video camera wielding robotic crawler and a high resolution zoom camera on the end of a pole, the inside of the tunnel came to life with highly detailed and very clear pictures.
The robotic crawler, aka Rovver, was lowered into the tunnel and proceeded to drive across the lumpy floor
of the tunnel to the location of the wooden shoring (see pictures at bottom of post). From this vantage, the Rovver’s self-lit camera beamed back crystal clear images of the wooden. In these images, the dangling electrical cord of the lighting
system was plainly visible. In total 4 sets of wooden shoring are visible and still standing in various stages of decay. After 60 years, the wooden braces fashioned from various scraps from the prison wood shop were still doing their job.
Images from the zoomable pole camera show that the tunnel beyond the shoring is collapse. As well, the images shown that the tunnel in the direction of the cell block was also collapse. The interpretation of GPR results and a good placement of the auger hole found the only open portion of the 1945 escape tunnel. And luckily, this portion was complete with standing wooden shoring and remnant electrical lighting wire.
At the end of the busy weekend, the crowds were gone, the equipment was pulled, and the auger hole into the tunnel was sealed. Re-discovered, explored, and documented, the Eastern State Penitentiary escape tunnel yielded more thrills and info than anyone had imagined. If you are ever in the Philadelphia area, I highly recommend you take a tour of this most historic prison.
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