Adventures in Archaeology: IBM had a Problem

Guest Post By Geology Expert John Carter

Sometimes the use of GPR can be absolutely hilarious, consider this case in point. Several years ago IBM had a problem with a set of pipes carrying hydrogen gas from an above ground storage tank across the parking lot of their plant in East Fishkill, New York. The hydrogen is used in making computer chips. IBM had issued a contract for some archaeological excavation work to be performed in their parking lot. The contractor was given blueprints of the lot that showed two sets of pipes in different places after they had been told there were only one set of pipes.

Needless to say with the information supplied the contractor wasn’t sure of exactly where the pipes were. He became especially nervous after some of the officials at IBM had informed him that if he broke either of the pipes it would cost him $8 million a minute. He had heard about Ground Penetrating Radar, so he found out who manufactured the units, and put in a phone call to the manufacturer, Geophysical Survey Systems, Inc. of Salem, New Hampshire who had a policy of giving GPR jobs to the nearest owner of one of their units to the job site.

Presently we received a phone call from the contractor explaining his problem. We showed up bright and early the next morning with our unit, set the instrument up, selected the proper antenna for the job, and went trolling for the errant pipes. The antenna we selected looks for the entire world like a power lawnmower with an extension cord leading back to the unit in the van. After we had been going back and forth in the parking lot for a while we attracted some attention from the denizens inside the plant, and out came some junior executive who asked what we were doing.

We explained what we were looking for, and how the GPR unit worked, and with that he went back into the plant. About twenty minutes passed when several more executives came out from the plant including the general manager who invited us, and our GPR unit, to come back into the plant. We marked off with a can of spray paint where we stopped with the GPR survey, and followed them into the plant. The general manager explained to us they were having the same problem inside the plant with the same set of pipes, and they also having the same problem finding the pipes because they had two sets of prints showing the pipes in different locations.

IBM is one of the most high-tech companies in the world, but their best effort was a janitor with a pair of bent coat hangers dowsing for the pipes. We got an extra job out of the deal where everybody paid us by the hour for our services.



This is how GPR works: It is similar too your kitchen microwave in that it uses a cavity magnetometer to generate the radar micro waves, but the similarity to a microwave oven ends there. The power generated by a GPR unit is roughly 1/20,000 of the power generated by a microwave oven. The beam is not focused, so it is not like a searchlight, but more like a floodlight. GPR does not generate a sharp image like a camera, but rather an image produced by the radar waves acting against the difference in dielectric strength between the earth and any object buried in the ground. This produces an echo that is returned to the GPR unit that converts it to an image on some form of monitor where it can be interpreted by the operator into useful information about subsurface conditions. The readout can be either a digital image on a screen, from an archaeology site sometimes,  or a printout from a multichannel oscillograph.

Most GPR units use both systems together because the printout is hard copy that can be stored. The digital copy is also stored in some sort of device that stores memory.

Author Bio John Carter is a geologist that paid his way through college as a commercial helicopter pilot in the NY Metro area. He has had extensive experience as a prospector, and operated an environmental consulting firm specializing in environmental site assessments and is certified by the State of Connecticut as an Environmental Analyst III. In his early life he worked as an experimental machinist on aircraft and electronic parts before receiving his degree as a geologist. Carter also owns the website Gold Mining and Prospecting.

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I own a Garmin 90 handheld GPS unit that is designed for use in aircraft that although it doesn’t have all the “bells and whistles” as newer models used for navigating on the ground even so it is quite capable of accurately laying out property lines, and corner locations that is exactly what is called for to layout and stake a claim.
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Use of GPR at the L’Ambiance Plaza Disaster

L’Ambiance Plaza was a 16 story residential project that was under construction in Bridgeport, Connecticut at the corner of Washington Avenue and Coleman Street when its partial frame collapsed on April 23, 1987. There were 28 workers that were killed, caught between the sandwiched concrete floors of the collapsed building. The site was immediately swarmed by many of the construction workers from other projects in Bridgeport who tried to save trapped workers. From the start it was quite apparent that finding any survivors would be a miracle.
The Darker Side of Archaeology: Use of GPR at the L’Ambiance Plaza Disaster

The Environmental Site Assessment as an Archeological Study

An environmental site assessment (ESA) is a report mandated by law designed to establish the well being of any piece of property that in practice usually applies to commercial and/or industrial properties. An ESA is divided into three parts called phases that are numbered I, II and III. A Phase I report is used to determine whether or not the possibility of a release of hazardous material has in fact occurred on a property by determining its prior history.
The Environmental Site Assessment as an Archeological Study

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Photos are in Public Domain

The Darker Side of Archaeology: Use of GPR at the L’Ambiance Plaza Disaster

L’Ambiance Plaza was a 16 story residential project that was under construction in Bridgeport, Connecticut at the corner of Washington Avenue and Coleman Street when its partial frame collapsed on April 23, 1987. There were 28 workers that were killed, caught between the sandwiched concrete floors of the collapsed building. The site was immediately swarmed by many of the construction workers from other projects in Bridgeport who tried to save trapped workers. From the start it was quite apparent that finding any survivors would be a miracle.


(This photo taken at the scene of the disaster illustrates what kind of problems we faced using GPR.)

Shortly after the accident we received a phone call from the Bridgeport Police requesting us to come to the accident scene as soon as possible with our Ground Penetrating Radar (GPR) to join in the search for survivors. As soon as we arrived at the scene of the collapse we set up our GPR unit and quickly discovered that although our unit had the capability of penetrating several feet into the ground, it was unable to penetrate the concrete used in the construction of L'Ambiance Plaza.

The construction methods that were used totally defeated the GPR because the floors were reinforced with rebar and heavy wire mesh. It was impossible to penetrate the concrete and get any meaningful images as a result of the very strong echoes from the steel reinforcements.

Strangely, the next job we received was determining if there were sufficient reinforcements of rebar in a construction project in the neighboring city of Norwalk, Connecticut. In this case the GPR was effective because the rebar was far enough apart, so the solar radar beam did not pick up any conflicting echoes.

This brings up the question of where you can't use GPR, and there are several different natural conditions that can block the radar beam.

The GPR is virtually useless in the following conditions:

• In concrete that is heavily enforced with rebar or wire mesh or any combination of both.
• If the soil is contaminated with salt; the salt will have a tendency to break up the radar beam causing a very shallow penetration that at times can be measured in millimeters making the use of GPR virtually impossible.
• The presence of excessive clay serves practically the same purpose since the penetration of the radar beam through clay can also be measured in millimeters.
  
  

(This shows a GPR unit at work at a forensic site)

Fortunately there are other places where GPR can be used to great effect. It can be used very effectively in penetrating solid stone. One of the early trials we conducted with ground penetrating radar was the Palisade Sill in New Jersey across the river from New York City. The radar beam penetrated to about 300 feet and showed the deposits of chromite that had settled through the molten basaltic magma from which the sill is composed.


(This is a readout showing five areas of interest that might be human remains. )

We have also used GPR to detect cavities in limestone underlying a stretch of Interstate 80 in western New Jersey. Some of these cavities were as small as a teacup and others were as large as a small house. The average depth of penetration in ordinary soil is about 12 feet, but that can very according to the amount of clay minerals the soil contains. The more clay that is present the less penetration.

GPR does not present a photo like image of conditions below the surface of the ground but rather a readout of geometric shapes and lines that require interpretation by a trained operator. It requires several weeks to train someone in the ability to properly interpret the readout from GPR on an environmental or archaeology site.

Author Bio John Carter is a geologist that paid his way through college as a commercial helicopter pilot in the NY Metro area. He has had extensive experience as a prospector, and operated an environmental consulting firm specializing in environmental site assessments and is certified by the State of Connecticut as an Environmental Analyst III. In his early life he worked as an experimental machinist on aircraft and electronic parts before receiving his degree as a geologist.

Read more: Ancient Digger Archaeology: The Environmental Site Assessment as an Archeological Study  
References:

1. L‘Ambiance Plaza, Wikipedia, http://en.wikipedia.org/wiki/L'Ambiance_Plaza
2. GSSI, http://www.geophysical.com/?gclid=CNf24rf056gCFYfe4AoduGyGDg
3. Personal Experience of John Carter

Illustrations:

1. Photot taken at the scene of the disaster illustrates what kind of problems we faced using GPR.
2. GPR unit at work at a forensic site Photo by Vadams
3. This is a readout showing five areas of interest that might be human remains. Photo by Matomj

The Environmental Site Assessment as an Archeological Study

Guest article by John Carter

An environmental site assessment (ESA) is a report mandated by law designed to establish the well being of any piece of property that in practice usually applies to commercial and/or industrial properties. An ESA is divided into three parts called phases that are numbered I, II and III. A Phase I report is used to determine whether or not the possibility of a release of hazardous material has in fact occurred on a property by determining its prior history. A Phase II report determines if in fact that a release has occurred on a property by taking samples from the property and subjecting them to a battery of lab tests. If in fact the results of this analysis returns indicating that there are indeed hazardous materials that are found on the property above the threshold levels mandated by law the property has to undergo a Phase III Investigation to determine the amount, extent and the effects on human and other life forms the contamination will cause. Photocopies are taken of each report for inclusion in appendix A. of the ESA, and a brief annotation is included in the finished assessment.



(This is an aerial photo of an industrial park in Manchester, CT showing several areas of environmental interest.  Try locating them on the photo, describe why they would be on interest, and try to determine which ones would become archeological sites in the future?)

Together the three phases of an ESA are very similar to an archeological study, but the single phase that develops the most information that pertains to a specific piece of property is Phase I. This part of an ESA starts in the reading room of the government body of the state that has charge of environmental affairs. This is a collection of environmental records that report any releases of hazardous materials that are known to have occurred on the property or that have occurred off the property, but could have compromised its environmental integrity.

The next stop is usually the state library where they keep other forms of documentation required for a site assessment like aerial photographs, insurance maps, city directories, telephone books and town histories. Even more information can be gathered from back issues of newspapers. Copies of all this documentation are included in Appendix B. of the ESA. As you gather this material you are also writing part of the ESA.

There is also a considerable amount of other information that has to be gathered from the town records of the town where the property is located among them are: Land Records dating back to 1940, or earlier if necessary. We once had to trace the land records back to 1763 because then the property in question had been the largest tannery in the state. Tanneries are one of the most environmentally damaging establishments there are; they can be a nightmare especially if they ever used the Chrome Tanning Process leaving behind a trail of Hexavalent Chromium contamination.

The local search continues with records from the Fire Marshall, the Planning and Zoning Commission, a search in the morgue of the local newspaper and finally statements that are taken from some of the locals who have had contact with the site. There is some additional material like a description of the process if any that has been manufactured or used on the site.

A Phase I ESA is written up and ends with a set of conclusions that affect the outcome of the ESA either it ends with the conclusion that no further environmental work needs be done. If there is historical evidence that the probability of a release occurring on the property is high then the nature of the release and its location is included in the conclusions, and the recommendation is that further environmental work is required so that the ESA continues with a Phase II investigation.

A Phase II ESA is designed to determine if in fact a release of hazardous materials did in fact occur on the property. Although this report is much shorter it deals strictly with the chemical analysis of air, water and soil samples from the site and sometimes “wipe samples” that are taken inside of any structures that are on the property that have been listed as suspect during the Phase I ESA. The various samples are taken at the site according to American Society of Testing Materials (ASTM) standards and transported under a Chain of Custody (CofC) to a certified analytical lab for analyses.

A similar report is drawn up to the Phase I only this time it describes the results of the analysis and reports on the allowable Environmental Protection Agency (EPA) guidelines for hazardous materials. The EPA has a table of the various contaminants of concern. If in the course of analyses any of these standards are exceeded the site is deemed contaminated, and the Environmental Analyst must proceed with a Phase III ESA.

Generally if a property fails a Phase II Investigation the owner or buyer walks away from the property allowing it to become a Superfund or RCRA property. This is the origin of many industrial properties that are designated as “Brownfields.”

A Phase III ESA is similar to a Phase II only it goes into much more detail because it not only tests for contaminants, but also tests for there extent and effects on humans and other life forms.
The similarities between an ESA are uncanny, and the ESA with some modifications could stand as a good plan for designing an archeological dig; all that is needed is to change the objectives. Rather then searching for hazardous waste releases you are hunting for artifacts of a previous age. The ASTM Standard for Phase I ESAs is ASTM 1577-05 and a guide for conducting an ESA is ASTM E1528 that explains the parameters of an ESA, or could be modified to an archeological site.

In truth, there are many similarities between an environmental establishment and an archeological site; the main difference is measured in years, and remember today’s site is tomorrows archeological dig that is performed to discover how people lived in the past. The ESA gives the analyst an insight into industrial archeology, and ultimately many of the same problems exist. Have you ever seen an ancient Superfund Site, they exist.

Author Bio

John Carter is a geologist that paid his way through college as a commercial helicopter pilot in the NY Metro area.  He has had extensive experience as a prospector, and operated an environmental consulting firm specializing in environmental site assessments and is certified by the State of Connecticut as an Environmental Analyst III.  In his early life he worked as an experimental machinist on aircraft and electronic parts before receiving his degree as a geologist.