Army City - Fort Riley

 

Other areas:

During the summer of 2002 another round of data acquisition at Army City wascompleted with funding provided by SERDP. This report provides initial and verypreliminary results obtained during that field season.In 1995-96 most of the entire town was geophysically surveyed by Geoscan Researchusing electrical resistance methods, discussed above. Their results provided goodindications of many features of the town as well as a paleo-channel to the northeast nowinvisible on the surface (see http://www.cast.uark.edu/nadag/projects_database/Somers1/Somers1.htm for additional details about this work).

In 2002, 1.6 ha were surveyed. Data from five geophysicalmethods, most of which respond to different dimensions of subsurface physicalproperties, are presented below, with many similarities and differences apparent. Anultimate goal of the project will be to employ the data together, simultaneously, utilizinga variety of new data fusion approaches that ultimately will indicate better detail and newinsights about this important site.

Thermal (palm 250IR), high resolution panchromatic and multispectral data from aerial(Duncan DI 4500) and space-based platforms (the QuickBird satellite) will soon be fusedwith the geophysical data to yield an even clearer understanding of the subsurface contentand organization of Army City. Vegetation patterns indicated on the surface duringfieldwork (see Resistivity, below) suggest great promise from aerial methods.

Site Mapping

A detailed mapping of all surface-visible features and indications of subsurface changeswas undertaken throughout the study area. There was a wealth of evidence about thesubsurface was detectable at the surface with the human eye. These data will ultimatelybe compared with the various forms of remote sensing evidence. GIS technology,together with new "data fusion" software, will ultimately allow thorough analysis,combination, and understanding of these data.

Resistivity Survey

Instrument: Geoscan Research RM-15 with MPX-15 multiplexer; Prospection depth: 0.5m; Sampling interval: 0.5 x m; Area surveyed: 16,000 m2 (1.6 ha); Date of survey:7/2002, Land Cover Type: Mowed Grass.

Resistivity SurveyThe principal northwest-southeast trending street, known as "Washington Street," is readily seen as are a number of other structures, including the "Orpheum Theater" in the north-central portion of the study block. Of large interest is the faint outline of a rectangular structure seen in the south-central portion of the study block that is indicated as a series of unconnected dots represent building footers.

These features are revealed despite the somewhat coarse sampling interval employed (relative to the size of these features), indicating the robust contrast they offered compared to the background data. Surprisingly, these anomalies are also clearly indicated by vegetation marks in the surface.

They can also be discerned in the GPR data but not in the other imagery. As shown in this portion of the total data, the resistance data clearly reveal individual walls and rooms of a large structure in the northwest, historically called the "Hippodrome." Some of these walls were visible as vegetation markings seen on the surface.

While soil resistivity and conductivity are the theoretical inverses of each other, the results of these surveys include important differences stemming from the very different instrumentation employed to obtain each data set and variations in the soil volumes evaluated. The raw conductivity data largely illustrate, at present, highly conductive buried pipes that lie beneath many of the buildings. Some building outlines are indicated, however, including a different visualization of the south-central rectangular structure.

Initial processing of these data employed despiking to remove some of the low- level metallic noise, a high-pass filter for trend removal, and a low-pass filter for further noise suppression. A number of subtle details not apparent in the raw data are enhanced and it becomes possible to visualize features within saturated areas around the many pipes.

Electromagnetic Conductivity Survey

Instrument: Geonics, Ltd. EM-38, quadrature phase; Prospection depth: 1.5 m, with peak sensitivity at 0.4 m; Sampling interval: 0.5 x 1.0 m; Area surveyed: 16,000 m2 (1.6 ha);

Date of survey: 7/2002. Land Cover Type: Mowed Grass.

While soil resistivity and conductivity are the theoretical inverses of each other, the results of these surveys include important differences stemming from the very different instrumentation employed to obtain each data set and variations in the soil volumes evaluated. The raw conductivity data largely illustrate, at present, highly conductive buried pipes that lie beneath many of the buildings. Some building outlines are indicated, however, including a different visualization of the south-central rectangular structure. Initial processing of these data employed despiking to remove some of the low- level metallic noise, a high-pass filter for trend removal, and a low-pass filter for further noise suppression. A number of subtle details not apparent in the raw data are enhanced and it becomes possible to visualize features within saturated areas around the many pipes.

Magnetic Gradiometry Survey

Instrument: Geoscan Research FM-36 fluxgate gradiometer; Prospection depth: up to 1.5m; Sampling interval: 0.25 x 1.0 m; Area surveyed: 16,000 m2 (1.6 ha); Date of survey:7/2002. Land Cover Type: Mowed Grass.

The magnetic gradiometry data markedly illustrate the distributions of iron and steel artifacts, including iron in concrete foundations, individual iron or steel artifacts like nails, nuts and bolts, etc., and buried iron pipes. Some of the iron pipes illustrate a pattern of alternating positive and negative values, indicating strings of magnetic dipoles that probably correspond with pipe joints. A comparison against the conductivity image suggests that some pipes may not be of ferrous metal. Magnetometry is particularly sensitive to fired materials; some of the response near the buildings may therefore point to bricks or possibly burned earth from the 1921 fire. A neighborhood variance balancing filter was employed to reveal greater detail in areas of low magnetic activity and reduce high dynamic ranges elsewhere; the result was also subjected to a low-pass filter.

Magnetic Susceptibility Survey

Instrument: Geonics, Ltd. EM-38, in-phase component; Prospection depth: about 0.5 m;

Sampling interval: 0.5 x 1.0 m; Area surveyed: 16,000 m2 (1.6 ha); Date of survey:

7/2002. Land Cover Type: Mowed Grass.

Magnetic Susceptibility SurveyThese data provide many new insights about the buried structures at Army City, possibly zones of brick debris, intensive burning, refuse dispersal, topsoil mounding or extraction. The raw magnetic susceptibility map does not illustrate the extreme anomalies caused by many of the numerous metal pipes that are seen in the other data sets. Initial processing of these data employed despiking, a high-pass filter to eliminate large zones of high measurement, and a low-pass filter for further noise suppression. A number of subtle details not apparent in the raw data are enhanced and it becomes possible to visualize the many features that exist within the saturated areas of high magnetic susceptibility.

 

 

 

Ground Penetrating Radar Survey

Instrument: Geophysical Survey Systems, Inc., SIR-2000 with 400 MHz transducer and survey wheel; Prospection depth: about 1.5 m; Sampling interval: 0.5 x 0.05 m; Area surveyed: 16,000 m2 (1.6 ha); Date of survey: 7/2002. Land Cover Type: Mowed Grass. GPR was a big question at this site for it lies in conductive clay/silt soils in the Kansas River bottomlands that have frequently been subjected to flooding.

 Ground Penetrating Radar Survey This illustration is a preliminary look at the GPR data, based on a composite of time slices resulting from the eight individual sub-blocks necessary to survey the entire area. All the slices are taken from the 5-15 nS range (TWTT; to perhaps .75 m depth). The slices are derived from the raw, unprocessed profiles, although background removal was performed. Seams are readily apparent between the eight blocks of data, as are stripes and other defects resulting from extreme temperatures and other circumstances (these defects will ultimately be corrected). Interestingly, a light rainstorm may actually have clarified results along the central area by exaggerating contrasts between building materials (e.g., concrete) and the surrounding soils.

 

 

 

Whatever the case, this initial look suggests great promise in these data. In particular, many details in the building and non- building areas are indicated that do not appear to occur in the initial data sets from the other instruments. Further data processing using a variety of common GPR transforms, gain balancing, and more detailed time-slicing will surely reveal many important insights, and at multiple depths.

An initial Army City report has been provided at

 

http://www.cast.uark.edu/~kkvamme/geop/army_city.htm.

http://www.cast.uark.edu/nadag/projects_database/Kvamme28/kvamme28.htm

 

Army City (14RY3193), Fort Riley, Kansas Geophysical Survey 1996-1997

Army City is a historic site in Riley County, Kansas, owned by the U.S. Army. The AD1917 military base is 92,400 square meters located on low rolling hills. Data from 1996-1997 surveys of this site, summarized below, were acquired for the current study. Army City was a World War I era commercial complex established to provide entertainment and other services to troops at Camp Funston (now part of Fort Riley, KS).The town was created in 1917 and presently rests under a hay field with almost no indications on the surface of its presence.

In 1996 and 1997, resistivity, magnetometry, and limited ground penetrating rada rsurveys were conducted along with limited archaeological excavation to demonstrate the eligibility of the site for listing on the National Register of Historic Places. A total of 3,600 square meters was examined with resistivity and 5,600 square meters were inspected with magnetometry. The geophysical instruments used were both made byGeoscan (RM-15 and FM36, respectively). The geophysical data was used to guide limited testing efforts for maximum information retrieval. The geophysical surveys enhanced other data sources in the nomination of this site to the NRHP.

Magnetic Gradiometry Survey

Instrument: Geoscan Research FM-36; Sampling Interval: 1 x 1 m; Prospecting Depth: 1-1.5 m; Area Surveyed: 5,600 sq m; Date of Survey: 1996 and 1997; Land Cover Type: Prairie.

Electrical Resistivity/Resistance Survey

Electrical Resistivity/Resistance Survey

Instrument: Geoscan Research RM-15; Sampling Interval: 0.5 m x 1 m; Prospecting

Depth: 0.5 m, 1 m; Area Surveyed: 3,600 sq m; Date of Survey: 1996 and 1997; Land Cover Type: Prairie.