Thermal Imaging and "seeing the unseen" at Industrial Heritage Sites

After years of talking about our potential to collaborate on remote sensing and geospatial mapping technologies, I finally had an opportunity to work with some colleagues at the Michigan Tech Research Institute (MTRI). We decided to scrape together some resources so we could experiment. Rick Dobson, Research Scientist, and David Banach, Assistant Research Scientist, were both going to be in Houghton in July for some other important meetings. We convinced their boss to extend their visit so that we could get a few days to fly UAVs over industrial heritage sites in the Copper Country. 

Figure 1: The Bergen Hexacopter and FLIR camera flying at the Quincy Smelter.

I took David and Rick to different places. After considering the gear we had and the time of year, we decided to focus our efforts on the Quincy Smelter site (Figure 1). The Quincy Smelter is the last standing 19th Century copper smelter in the country. Built in 1908 by the Quincy Mining Company, people worked at the smelter until 1971, when the company finally shut down the operation. The company locked the doors and left the site alone, with the hope they could reopen and resume operations in the future. The reopening never happened, but even after years of neglect, the facility is still remarkably intact. The National Park Service recognized the importance of the smelter as a heritage resource, including it in the Quincy Mining Company National Historic Landmark District and ultimately within the boundaries of Keweenaw National Historical Park. While the Franklin Township held the property for many years, caring for it as well they could, the Keweenaw National Historical Park Advisory Commission finally acquired the property. With the help of the Quincy Mine Hoist Association and the Quincy Smelter Association, the site is now open for guided tours Monday through Saturday, late June through mid-October. (Information on Facebook sites here and here!)

Figure 2: GIS overlay of 1906 plan map superimposed over a geo-referenced aerial image, showing the location of the Slag Shed and Scales building, and some underground water pipe locations. These were some of the targets we were investigating.

Reports and publications from this work will be submitted to the Keweenaw National Historical Park Advisory Commission so the information can be used to guide future management decisions and in the development of interpretive programming. Copies will also be archived at Michigan Tech's University Archives and Historical Collections, and if given permission, we will make them free to download from the Department of Social Sciences website.

Figure 3. Geo-referenced high-resolution photogrammetric DEM with the 1906 Slag Shed and Scales outlined in red.

Figure 4: FLIR Vue Pro R thermal camera onboard of the Bergen Hexacopter.

Figure 5: The Bergen Hexacopter and FLIR camera at the Quincy Smelter

Figure 6: Geo-referenced FLIR Vue Pro R thermal imagery overlain on the photogrammetric DEM with the 1906 Slag Shed and Scales outlined. Differential thermal patterns reveal indications of some sub-surface structures at the location of the Slag Shed and Scales building.

After reviewing and mosaicking the thermal imagery, cooler sub-surface features appeared where the Slag Shed and Scales building once existed in 1906. Lots of features! Some of these features, like the lumber scrap around the standing shed, are on the surface of the ground and are visible in the optical imagery. But most of the patterned strips that look like railroad ties are invisible and nobody had any idea they were there (Figure 6 and 7). At first glance, David thought these features were ties for rail tracks, but because they are geo-referenced and imported into ArcMap, he could measure them. The smaller features measure nearly seven feet, much larger than today’s standard 4.5-foot tie for modern gauge track (details in Figure 7). They may be cross ties for rail track, since larger size ties were used. Another possibility is that these features are some sort of foundational support for the Slag Shed and Scales building.  

Figure 7. Detail of geo-referenced FLIR Thermal Image photomosaic superimposed on the DEM in the area of the Slag Shed and Scales Building.

We will have to do some "ground truthing" to find out what the different types of anomalies actually are under the ground! I will ask my students in Fall 2019 if they'd like to volunteer to help with some of the testing to assess the thermal anomalies. Right now, we've shared our findings with other archaeologists that have done work at the site over the years to get their thoughts. Hopefully we will be able to find funds to continue the study. We'd like to do another round of thermal imaging during the evening "cool down" as the ground emits all the energy it has absorbed during the day. I'd also like to add data captured using multi- and/or hyper-spectral instruments, since the different energy spectra all can reveal different potential about the site. 
My colleague Jeremy Shannon and his students ran some Ground Penetrating Radar at the site, and we'd like to pull his data into the GIS. If we can get some additional equipment for Tech's GPR, we'd also be able to more efficiently scan the entire work yard space at the smelter. The GPR has potential to add information about more deeply buried features, such as pipes and the boundary between the poor rock fill and the original shoreline and lake bottom.
I am grateful to Rick and David and my colleagues at MTRI for their willingness to collaborate. Remote sensing and digitization tools are becoming much more readily available to archaeologists after a long period where only elite research institutions had common access to these technologies. I know that Rick and David are terribly busy with other research projects and I really value their efforts to help me spark some collaborative work. We are also using this material to create educational materials we can use in classrooms at Michigan Tech where students can use our tools to look at local sites and solve real world problems for local organizations. These are interesting and important technologies for industrial heritage and emerging professionals in the field must know how to use them, as operators and/or collaborators!

Michigan Technological University's Industrial Archaeology students have helped the preservation efforts in many ways over the years, by volunteering time as archaeologists conducting forensic rescue excavation and recovery after an arson in 2010, assisting with cultural resources monitoring during ongoing environmental remediations, and advocating as volunteers within the community as part of the Quincy Smelter Association. Exemplary of that work, check out this blog that Sean Gohman and Craig Wilson put together as part of that effort! They included lots of photographs, maps, and historical discussion about the smelter. That blog is now an archived resource. The Copper Country Explorer is an independent website by Mark Forgrave has published lots of pics and information about the Quincy Smelter.

The Quincy Smelter is typical of legacy sites in industrial heritage because it included a landscape with a legacy of environmental contamination that posed both ecological and public health hazards. Rather than acting hastily to demolish the site, many different partners worked for years to find ways to secure the site, remediate the toxic materials that posed threats to health or ecological systems, and start the bring the site back. The Environmental Protection Agency just published a short summary of the story of the smelter, Quincy Smelter: From Stamp Sands to National Historic Park. Michigan Tech students and faculty have supported the efforts to make wise decisions through the remediation process. As two examples, Fred Sutherland and Sean Gohman have both monitored remediation and clean up projects in past years. 

These legacies make the smelter an ideal laboratory for us where we can test the applications of various remote sensing technologies and work through the data fusion challenges, while also contributing to a long term preservation and interpretation effort. Can we use remote sensing technologies to map underground features? That would be much less expensive than having an archaeology crew do subsurface testing of the entire smelter complex to find those features. Once identified, the managers can plan to avoid important features during redevelopment. Can remote sensing help identify targets of that have high risk of toxic contaminants? Doing so will also help with planning. Understanding the subsurface "landscape" of historical features is essential to thoughtful and wise planning as the KNHP Advisory Commission and it's partners work to preserve the site and bring it back to life.

We started last July by flying two instrument platforms: a DJI Phantom Quadcopter fitted with a 14 Megapixel Color Camera and a Bergen Hexacopter with an onboard FLIR Vue Pro R (radiometric) thermal sensor. Before the field days, I had gathered high-resolution scans of historic maps and blueprints of the Quincy Smelter site from the Michigan Tech's archive and the collections at the Keweenaw National Historical Park (some of those maps are also here). David set up a Geographic Information System database using all the historic plan maps that I could find. He traced the building footprints so that we could superimpose those plots overtop of any geo-referenced image of the site (Figures 2 and 3).

Archaeologists have long used aerial thermal imaging to spot features and sites underground. The technique works because different materials, such as a stone foundation or a capped and buried well shaft, will absorb and radiate heat energy differently and patterns in this "differential thermal loading" therefore can reveal clues about what is buried under the ground. The Bergen Hexacopter UAV platform carried an onboard FLIR Vue Pro R (radiometric) thermal sensor for several flights during the early morning (Figures 4 and 5). We'd received FAA approval for a flight plan in the narrow window of time between civil twilight (when it becomes light enough to see) and actual sunrise. After the sun breaks over the horizon, the thermal energy of direct radiation overwhelms and "washes out" any subtle thermal variation in the ground surface. The drone captured most of our best images during a flight at about 6:45 AM. When researchers use thermal imaging in archaeological survey, it is common for them to also capture a series of images as the landscape cools down, flying between sunset and evening twilight. We didn't have FAA permission to conduct those flights, so we took only "warm up" images as the site began differentially absorbing the ambient energy from morning twilight, before the sun rose over the buildings.



Like a GPS-equipped camera, the sensor captures images that are stored in JPEG format and can be used in GIS software such as ArcMAP and image mosaicking software such as Microsoft Image Composite Editor (ICE). The FLIR sensor records the radiated thermal energy as it varies from spot to spot on a surface, then assigns a false-color pixel to each value. This sensor has an imaging resolution of 640 x 512 and can sense temperatures between -4°F and 122°F. 

David used ICE to mosaic the individual images and then import that mosaic into the GIS. The results of his work were pretty remarkable! (See Figure 6 below).

In my next post, I'm going to talk more about Rick's photogrammetry work. He has produced a remarkable Digital Elevation Model (DEM) of the site with tremendous potential to contribute to site management, study, and interpretation. He is also designing experiments now to compare the applications of LiDAR and optical photogrammetry in industrial heritage. 




If you would like to make a tax deductible gift in support of work at this and the Cliff Mine, you can make a gift to the Michigan Tech Fund online at this address:
https://www.banweb.mtu.edu/mtu/mtf/gift/give.xsql?desig=18143-Cliff%20Mine%20Arch-DeptSocSci-Scarlett
Or by contacting Benjamin Larson at the Michigan Tech Fund at 906-487-2464 or balarson@mtu.edu. Donated funds provide for student scholarships and equipment purchase and maintenance in the Industrial Heritage and Archaeology program.

Rural Community Sustainability: Research, Applications, and Engagement in Calumet, Michigan

Rural Community Sustainability: Research, Applications, and Engagement in Calumet, Michigan

Dr. Richelle Winkler

Assistant Professor of Sociology & Demography

Environmental and Energy Policy Program

Department of Social Sciences

Michigan Technological University

Environmental Engineering Graduate Seminar
Monday, February 25, 2013 3:00-4:00 PM
Great Lakes Research Center (GLRC), room 201

Rural communities across the United States and around the world have long suffered from diseconomies of scale and dependence upon an exported extractive resource base to outside interests in more urban locations. Most of our rural communities are in decline demographically, economically, and socially. They face unique challenges and opportunities in the context of an increasingly “flat” and globalized world. My research aims to understand how rural communities transition from a legacy of resource dependence and population decline toward vibrant sustainable futures. What are these challenges and opportunities and how can they be overcome?

This presentation will explore the concept of rural community sustainability and describe ways in which the natural resource/economic base in rural communities is related to age-specific migration patterns. Then, I will focus on a new project underway in Calumet, MI that specifically investigates community efforts toward sustainability in this community with a legacy of natural resource dependence. Taking a community based research approach, I am engaging with community groups to investigate the potential for redevelopment focused on alternative energies, including solar and mine water geothermal.

Iron, Oxygen and Salt

Iron and the metals derived from iron decay through several processes, but the main types of corrosion of interest to us are caused by reactions with Oxygen and Chloride.

Oxidation is the most important form of iron corrosion for our study. This corrosion results from the formal combination of oxygen with iron. Oxidation is an electrochemical process involving the formal removal of electrons from iron when it combines with oxygen. Iron has a negatively potential electromotive force (EMF), providing it a greater tendency to lose electrons and form positive ions. In contrast, copper is a more 'noble' metal with a higher EMF. The physical and chemical integrity of cupreous metals or artifacts will thus be preserved for a longer period of time compared to ferrous artifacts.

Electron flow is essential for oxidation. The process of oxidation occurs within a "galvanic cell," also known as an electrochemical half cell. Galvanic cells are created when two different metals or different areas of the same metal allow electrons to flow between them, from the positive anodic area to the negative cathodic area. Electrons flow from the anode to the cathode, breaking down the iron corrosion compounds at the anode. Oxygen bonds with the positive iron ions at the anode. This may occur numerous times to produce various types of oxidation and millions of individual galvanic cells are present on a single corroding artifact. Some people refer to the outcome of all these tiny cells as pitting corrosion.

Another major cause of metals corrosion are salts. In common use, salt refers to a collection of chemicals that include Sodium and Chloride atoms.  Conservators are concerned with how these ions electrochemically interact with metals, particularly chlorides.  When chloride atoms are ionised they become very reactive, and aggressively seek to interact with other molecules and ions. Concentrations of chlorides are a common salt water, for example, in maritime environments. Chlorides often saturate archaeological artifacts submersed in marine environments. Chlorides react with oxygen in a similar corrosive reaction to that described above.

The presence of chlorides exacerbates problems for conservators.  Chlorides readily go into solution, particularly in water.  When dissolved into a fluid solution, chloride ions facilitate all the corrosion processes, including what engineers would call galvanic and crevice corrosion.  In a general sense, the chemical reactions are all built around the same electrochemical reactions, but these reactions are encouraged or retarded by different structures, environments, and materials (or "material-environment systems" in engineering speak).

The artifacts recovered by Michigan Tech research teams have usually come from terrestrial environments drained by rain and freshwater runoff, thus chlorides are generally not a significant concern. At the West Point Foundry, for example, even though the estuarine environment of that section of the Hudson River could be brackish due to that river's famous tidal flow, most of the artifacts recovered during excavation came from parts of the site above the immediate area of foundry marsh and cove.  Our research teams were lucky, as are the landowners The Scenic Hudson Land Trust.  The absence of chlorides meant that ferrous iron artifacts recovered from this historic industrial site were inherently more stable than those impregnated with chlorides in solution. This gives field and lab archaeologists and conservators more time to deal with potential corrosion and decay.

Michael Deegan was the first collaborator on the West Point Foundry project to undertake a study of corrosion at the site.  He and I co-authored an article summarising our findings after dedicating time in my Archaeological Sciences course, examining corrosion and conservation at the West Point Foundry site with one of our collaborators.

I will summarise the molecular forms created through the corrosion processes in another post.  What I hope readers understand from the posts so far is that the decay of metals, particularly iron, is a "natural" electrochemical reaction that occurs unless something prevents it from happening.  Factors that enhance or retard the flow of electrons drive both the extent and rate of decay--the presence of liquid water and the presence of chloride irons (salts) are both critically important in the process.

Moreover, these factors do not need to be visible to the naked eye! Microscopic pores, fissures, and stress cracks all absorb molecules from the environment (even when that environment is arid).  Corrosion is almost always occurring, even when the object appears to be dry and clean in your storage facility.  Corrosion occurs slowly even while the object sits on the shelf in front of you in a museum!

For those undertaking more research on this topic, we have found these sources useful:
Donny L. Hamilton (1997) provided discussions of metals corrosion which I have found very useful. Other detailed treatments can be found in N. A. North (1987), Bradley Rodgers (1992, 2004), and Janet Cronyn (1990).


Cronyn, Janet M.
1990 The Elements of Archaeological Conservation. Routledge, London.

Hamilton, Donny L.
1997     Basic Methods of Conserving Underwater Archaeological Material Culture. Legacy Resource Management Program, United States Department of Defence, Washington, D.C. Retrieved from https://www.denix.osd.mil/denix/Public/ES-Programs/Conservation/Underwater/archaeology.html on September 12, 2007.

North, N. A.
1987 Conservation of Metals. In Conservation of Marine Archaeological Objects, edited by C. Pearson, pp. 207-252. Butterworths, London.

Rodgers, Bradley A.
1992 The East Carolina University Conservator's Cookbook: A Methodological Approach to the Conservation of Water Soaked Artifacts. Program in Maritime History and Underwater Research, Department of History, East Carolina University, Greenville, North Carolina.

Rodgers, Bradley A.
2004 The Archaeologist’s Manual for Conservation: A Guide to non-Toxic, Minimal Intervention Artifact Stabilisation. Kluwer Academic/Plenum Publishers, New York.

and our article:
Deegan, Michael and Timothy James Scarlett.
2008 The Conservation of Ferrous Metals from the West Point Foundry Site. Bulletin of the New York State Archaeological Association 124: 56-68.

Fire at the Quincy Smelter site

Last night and early this morning, several local fire crews responded to an emergency call about a structure fire at the site of the historic Quincy Smelting Works.  The smelter, built in 1898, is the last copper smelter standing in the Keweenaw Peninsula. I have heard many people claim that this is one of last and best preserved nineteenth and early twentieth century copper smelters in the world.

The buildings that burned were the Carpenter Shop and it's Lumber Shed.  The smelter blog included pictures taken of these two buildings before the fire, along with a description of their history:

The Quincy Smelter's Carpenter Shop and Lumber Shed from the blog: http://quincysmelter.wordpress.com

More photographs and text about the support buildings were posted by the Copper Country Explorer:
http://www.coppercountryexplorer.com/2009/12/the-support-buildings-p1/

The fire started at about 11 pm on Saturday night.  Due to it's location on the water in Ripley, the fire was visible from all over downtown Houghton.  Here is the "stub" story in the Mining Gazette:

The Daily Mining Gazette's photo in their coverage of the fire.

Photos of the event are finding their way to media sites like Flickr.com.

This morning I went down to see the damage.  I am very grateful to the firefighters for working so hard to save the Stock House, which was scorched by the heat, and the other buildings in the immediate vicinity of the Carpenter Shop.  Here are some pictures from my cell phone camera of the ruined buildings this afternoon: