WATER POLLUTION CONTROL RESEARCH SERIES
14010 EHN 04/71
      DETECTION OF ABANDONED
     UNDERGROUND COAL MINES
      BY GEOPHYSICAL METHODS
u.s. ENVIRONMENTAL. PROTECTION AGENCY

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          WATEK POLLUTION CONTROL RESEARCH SEIZES
The Water Pollution Control Research Series describes the
results and progress in the control and abatement of pollution
in our Nation's waters.  They provide a central source of.
information on the research, development and demonstration
activities in the Environmental Protection Agency,  through
inhouse research arid grants and contracts with Federal,  State,
and local agencies, research institutions, and industrial
organizations.

Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Chief, Publications Branch
(Water), Research Information Division, R&M, Environmental
Protection Agency, Washington, B.C. 20460.

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           DETECTION  OF ABANDONED  UNDERGROUND  COAL
                 MINES  BY GEOPHYSICAL METHODS
                              by
                 HRB-Singer, Incorporated
               Environmental Sciences Branch
                        Science Park
             State  College, Pennsylvania 16801
                            for  the

              ENVIRONMENTAL PROTECTION AGENCY

                           and the

    PENNSYLVANIA  DEPARTMENT OF ENVIRONMENTAL  RESOURCES
                    Project 14010  EHN

                       April 1971
For salo by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.00

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                  EPA Review Notice
This report has been reviewed by the Environmental Protection
Agency and approved for publication.  Approval does not
signify that the contents necessarily reflect the views and
policies of the Environmental Protection Agency nor does
mention of trade names or commercial products constitute
endorsement or recommendation for use.

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                             ABSTRACT
Acid drainage produced by abandoned coal mines continues to cause
serious water pollution problems.  Without knowing the exact location
of the concealed openings and the extent of the mine, the application
of known, at source abatement techniques is virtually impossible.
Drilling is the only known method for accurately determining the
location and extent of the mine voids, but this is extremely expensive.
This project attacks the problem through field studies of the following
geophysical methods:  electrical resistivity, self-potential, infrared
radiometry, total field and differential magnetometry, seismic refrac-
tion and reflection, very low frequency electromagnetic and induced
polarization over well documented, drift, coal mines.  Airborne
infrared radiometry proved to be an excellent tool for detecting and
mapping acid mine/fresh water sources, acid mine/fresh water drainage,
and fracture traces under selected conditions.  Resistivity and
magnetics anomalies coincide with some (not all) drift mine entries.
Induced polarization data shows some apparent correlations with mine
workings.  Other methods tested did not yield correlatable information.
Conventional geophysical approaches to this problem do not appear
adequate for the task.  Unconventional approaches including high fre-
quency seismic, shear wave seismic, and induced polarization methods
may provide answers pending their further development.

This report was submitted in fulfillment of Project 14010EHN under
the partial sponsorship of the Water Quality Office, Environmental
Protection Agency.
                                 iii

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                              CONTENTS
Section




  I          Conclusions




  II         Recommendations




  III        Introduction




  IV         Selection of Techniques




  V          Site Selection




  VI         Field Measurements




  VII        Data Analysis and Technique Evaluation




  VIII       Field Validation




  IX         Problems and Corrective Action




  X          Acknowledgments




  XI         Bibliography




  XII        Appendix - Discussion of Methods
Page




  1




  3




  5




  9




 13




 31




 39




 75




 77




 79




 81




 89

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                              FIGURES
                                                                    ?aee
 1      Mills #4 Coal Mine - Location Map                            17

 2      Map of the Mills #4 Mine                                     19

 3      Bitumen #1 and #2 Coal Mines - Location Map                  21

 4      Map of the Bitumen #1 Coal Mine                              22

 5      Map of the Bitumen #2 Coal Mine                              23

 6      New Watson, Old Watson, Big Spring #1, Knowles and           26
        Hoover Coal Mines - Location Map

 7      Map of Part of the Old and New Watson Mines                  27

 8      Map of the Big Spring #1 Coal Mine                           28

 9      Map of Part of the Knowles Mine                              29

10      Location of the Electrical Resistivity Depth Profile         40
        Stations, Layer Boundaries and Apparent Resistivity
        (ohm-feet) of the Layers at the Mills #4 Mine

11      Constant Depth Resistivity Profiles Over the Mills           42
        #4 Mine Entries

12      Resistivity Traverse Data at Selected 'a' Spacings           43
        (feet) Relative to the Mills #4 Mine Workings

13      Bitumen //I Coal Mine, Survey Line #1, Cross Section          44
        with Resistivity, Magnetics, Self Potential Traverse
        Data

14      Bitumen #1 Coal Mine, Survey Line #2, Cross Section          45
        with Resistivity, Magnetics, and Self Potential
        Traverse Data

15      Electrical Resistivity and Magnetic Field Data Across        47
        the New Watson Coal Mine Drift Entries

16      Electrical Resistivity and Magnetic Field Data Across        48
        the Old Watson Coal Mine, Right Drift Entry
                                 vi

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                                                                    Page
17      Electrical Resistivity and Magnetic Field Data Across        49
        the Big Spring #1 Coal Mine, Drift Entry and Fan Entry

18      Computer Plot of the Earth Potential Around Survey           51
        Station #2, Mills #4 Coal Mine

19      Self-Potential Computer Generated Contour Map Over a  i       53
        Portion of the Bitumen #2 Coal Mine

20      Mills #4 Coal Mine, Survey Line #4 (Control Line - No        54
        Mining Activity) Cross Section with Induced Polariza-
        tion Data  (Frequency Domain)

21      Mills #4 Coal Mine, Survey Line #6, Cross Section with       55
        Induced Polarization Data (Frequency Domain)

22      Mills #4 Coal Mine, Survey Line #5, Cross Section with       56
        Induced Polarization Data (Frequency Domain)

23      Knowles Mine, Mine Entry Survey Line, Cross Section with     58
        Induced Polarization Data (Frequency Domain)

24      Magnetic Field Data Across the Mills #4 Coal Mine            59
        Entries

25      Total Magnetic Field Traverse Plots for Survey Lines         60
        1 Through 10, Bitumen #2 Coal Mine

26      Parts of Two Seismograms Recorded Over 'B' Main,             64
        Bitumen #2 Coal Mine

27      Utility of Airborne Infrared Imagery for Detection of        66
        Acid Mine/Fresh Water Sources; pH Values of Water
        Sources Indicated; 14 April 1971

28      Generalized Geologic Structural Trends for the Houtzdale     70
        7 1/2' Quadrangle

29      Linear Geologic Trends for the Bitumen Mines Area            73
                                vii

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                              TABLES
No.                                                                Page


1      Summary of Evaluation of Possible Techniques                 11

2      Mine Sites Inspected and Rated by Selection Criteria         16

3      Generalized Stratigraphic Section for the 'A' Seam           20
       Coals of the Philipsburg-Houtzdale Synclinal Basin

4      Stratigraphic Section for the Bitumen Coal Mines Area        25

5      Tabulation of Information Collected at Mine Sites            32
                               viii

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                            SECTION I

                           CONCLUSIONS
1.   Airborne infrared radiometry was successfully used for detecting
and mapping acid mine/fresh water sources, acid mine/fresh water
drainage, and fracture traces.

2.   Electrical resistivity and magnetics data showed anomalies asso-
ciated with some (not all) of the shallow drift mine entries.   This
success could not be extended to deeper, more practical depths due to
the lack of resolution and sensitivity of the conventional resistivity
configurations.  In the case of magnetics, the one gamma sensitivity
of available magnetometers limits the detection depth to shallow cases.
Background noise is a problem with high sensitivity magnetometry.

3.   Induced polarization (IP) data, although limited, illustrates
apparent correlations with mine workings.

4.   Conventional approaches with self-potential, very low frequency
(VLF) electromagnetic and seismic refraction and reflection did not
yield correlatable information.

5.   No conventional geophysical approaches to this problem appear
adequate for the task.  A given approach may work under very rigid
conditions, but will not work when applied to another case or to
general conditions.  A significant increase in the state-of-the-art
in both technique and instrumentation will have to take place before
abandoned coal mines can be satisfactorily detected and mapped.

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                            SECTION II

                         RECOMMENDATIONS

The project was an experimental study of a number of different geo-
physical tools over selected drift coal mines.  Limited successes were
achieved with certain tools, as noted in the conclusions.  Exploitation
of some of these successes should be considered.

Airborne infrared radiometry succeeded as a reconnaissance tool for
locating water drainage sources and should be pursued in this regard.
Segments of drainage basins that are serious acid mine water problem
areas should be overflown.  The flights should be made at optimum
detection seasons (late fall or early spring).  Collateral data
(topographic maps, aerial photography) should be. used to aid in the
discrimination of the acid water from the fresh water sources.  Field
checking will determine the accuracy of this approach in discerning
and mapping the acid water sources relative to the fresh water sources.

The primary conclusion of this program is that conventional geophysical
approaches to the problem do not appear adequate for the task.  The
following developments of an unconventional nature are recommended
based on experimental and theoretical considerations.

High frequency seismic (to 1000 hertz) equipment theoretically promises
to resolve subsurface features the size of mine workings.  Adaptation
or development of equipment of high enough sensitivity/power to over-
come the high absorption rates expected should be applied in a field
testing program.

In that the induced polarization experimental work performed on this
project appears to be the only reported shallow earth IP work of this
type, basic procedures and techniques were borrowed from mining geo-
physics.  Some success was noted even though these approaches were not
optimum.  On the basis of the moderate success, it is recommended that
field experiments with the IP method at higher power inputs, smaller
electrode spacings and unconventional electrode arrays be employed.

Seismic shear waves will not be propagated by voids.  This property may
be utilized for void detection.  Shear wave energy sources and receivers
are not generally available.  Equipment development for field experiments
may be required but should be pursued.

One of the mine sites has been lost to future scientific study due to
strip mining.  The other sites are not presently in danger, but it would
behoove agencies interested in solving some of the problems of abandoned
deep mines to consider the utilization of these sites and their data
against such an eventuality.

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                           SECTION III

                           INTRODUCTION
The problem to which this project was addressed was the investigation
of techniques for the detection and delineation of subsurface voids.
In particular, the voids sought are concealed, abandoned, underground
coal mines and associated portals, slump zones, vents and water drain-
age ways, both natural and man-made.  Characteristically, backfill and/
or overburden cover the mined areas and all apparent entrances and
vents.  The cover is variable in age, being related in some cases to
subsequent strip mine operations.  Slumping, fracture and collapse of
portions of the cover of the mine are characteristic.  Most of the mine
areas of interest possess generally moderate to locally steep topography.

These mined areas are real and potential sources of acid mine water.
Rainwater and groundwater percolate through the worked-out rooms and
drifts, react with the sulfide minerals present, permeate the cover and
eventually find their way to nearby streams.

In order to eliminate this source of water pollution, one of two at-
source control measures must be taken; these are:   (1) the routes of
water movement into the mine workings must be located and sealed or (2)
the routes of egress of the acid water from the mine workings must be
located and sealed or redirected.  In short, the mine workings have to
be sealed against water movement.  However, in order to seal against
water movement, the mined areas and the routes and avenues of water
movement must be located.

Drilling is currently the Drily "tried and true" technique to locate
these sources of acid mine water.  However, cost effectiveness considera-
tions dictate that drilling is not a practical tool for even a moderate
scale attack on the problem.  On the other hand, geophysical techniques
potentially offer an economical alternative means of detecting and
delineating these mined areas and the avenues of water movement.

Geophysical methods have been applied to similar detection problems in
recent years.  The study of groundwater hydrology, karst terrane
characterized by buried caves, solution channels or sinkholes and the
location of ore bodies by the detection of zones of mineralization are
representative of related problems that have been successfully attacked
by geophysical methods.

This project involved the application of selected geophysical sensors
and techniques to the problem of detecting and locating concealed, aban-
doned, underground coal mines and associated water drainage movement.

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An extensive field testing program was performed over eight selected
mines for which maps were available.  The following geophysical methods
were tested at these sites:  electrical resistivity, self-potential,
airborne radiometry, total field magnetometery,  differential magneto-
metry, seismic refraction and reflection, VLF electromagnetic, and
induced polarization.  (Section XII, Discussion of Methods, introduces
some of the basics of these approaches.)

Even though the project was of a feasibility nature, definite objectives
(albeit ambitious) were proposed.  These seven objectives of the project
are listed on the following page, as well as a qualitative breakdown of
their relative achievements.

Program objectives were to be accomplished by attacking the problem in
five phases, covering a period of eighteen months.   These phases were:

1.   Selection of Techniques and Site Selection

2.   Field Measurements

3.   Data Analysis and Technique Evaluation

4.   Field Validation

5.   Technical Report

The work phases are discussed in detail in the following sections.

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OBJECTIVES
1. DETECTION AND LOCATION OF
CONCEALED, ABANDONED COAL MINES
2. DETECTION AND LOCATION OF
PORTALS, FRACTURES, FAULTS,
JOINTING PATTERNS. SLUMP ZONES,
AND OTHER AVENUES OF WATER
MOVEMENT INTO AND OUT OF THE
MINES
3. DEFINITION OF THE OPTIMUM
METHOD OR MORE LIKELY. THE
OPTIMUM COMBINATION OF METHODS
REQUIRED FOR #1 AND #2
4. DEVELOPMENT OF THE OPTIMUM
FIELD PROCEDURES AND TECHNI-
QUES REQUIRED TO ACCOMPLISH
#1 AND #2
5. DEFINE THE QUANTITY, DIMEN-
SIONS AND COMPACTION OF THE
COVER TO SEAL THE MINE.
6. DEVELOPMENT OF COMPUTER DATA
REDUCTION METHODS TO SATISFY
THE REQUIREMENTS OF CERTAIN
GEOPHYSICAL METHODS APPLIED
TO THIS PROBLEM.
7 RECOMMENDATIONS FOR
THE DEVELOPMENT OF AN UNCON-
VENTIONAL METHOD OR MODIFICA-
TION OF AN EXISTING METHOD
FOR ITS OPTIMIZATION IN THIS
PROBLEM.
FULFILLED





X
X
PARTIALLY
FULFILLED
X
X





UNFULFILLED


X
X
X


REMARKS
SOME SUCCESS HAS BEEN NOTED WITH
THE RESISTIVITY AND MAGNETICS
METHODS IN DETECTING SHALLOW,
BURIED DRIFT MINE ENTRIES.
INDUCED POARIZATION SHOWED APPAR-
ENT PROMISE AT DETECTING MODERATE
DEPTH (60' ) MINE WORKINGS
AIRBORNE INFRARED IMAGERY SUC-
CESSFUL IN DETECTING AND MAPPING
ACID MINE/FRESH WATER SOURCES
AND DRAINAGE. AS WELL AS, FRAC-
TURE TRACES.
MOST OF THE EFFORT WAS DIRECTED
AT ESTABLISHING WORKABLE
TECHNIQUES.
MOST OF THE EFFORT WAS DIRECTED
AT ESTABLISHING WORKABLE
TECHNIQUES.
MOST OF THE EFFORT WAS DIRECTED
AT ESTABLISHING WORKABLE
TECHNIQUES.
THE STAMPEDE PACKAGE AND THE
VARIOUS SUBROUTINES THAT HAVE
BEEN ADDED FULFILL THIS OBJECTIVE.
HIGH FREQUENCY AND SHEAR WAVE
SEISMIC, INDUCED POLARIZATION
UNCONVENTIONAL ELECTRODE ARRAYS
AND HIGH POWER, AIRBORNE INFRARED
RADIOMETRY.
AP11374
-7-

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                            SECTION IV

                      SELECTION OF TECHNIQUES
The primary objective of the research program was the application of
existing geophysical methods and techniques to the detection and de-
lineation of abandoned, underground coal mines and associated water
drainage.  Prior to initiation of field activities, an intensive
literature search was made in order to learn of the latest pertinent
experiments in shallow-earth geophysics.  Visits and personal communi-
cations were extended to government agencies, universities and
industrial firms to gain further information on the state-of-the-art
in instrumentation and field techniques.  From these sources it was
concluded that there has been a prominent lack of investigation from
bedrock depths 'to several hundred feet.  (The one exception to this
statement is in the area of hydrological exploration and studies;
however, these investigations were generally confined to alluvial
materials.)  It was thus apparent that much of the field measurements
and analysis oriented toward the project objectives would be pioneer
in nature.

The application of geophysics to this problem is based on detection of
contrasts in the physical properties between the rock strata surround-
ing the mined areas and the water avenues and the mined areas and
water avenues themselves.  These properties include:  magnetic suscep-
tibility, elastic properties, electrical resistivity, radiometric
parameters, inductive electrical and magnetic properties and spontan-
eous/natural voltage generation.  Measurements are made at the ground
surface or certain ones from an airborne platform.

The local variations from normal/background or expected conditions are
suspect as related to mining features or water avenues and correlations
are sought relative to information on the mine map.

Techniques

Prior to the initiation of field activities the various geophysical
techniques were evaluated for their potential application to this
problem.  In summary, the following criteria were used:

     Portability
     Speed of Data Collection
     Cost
       Capital Investment
       Maintenance
     Ease of Data Analysis

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     Accuracy and Precision
     Information on Quantity and Dimensions of Excavation Required to
     Seal Mine

The evaluation was subjective,  but this was expected since a truly
quantitative evaluation means did not exist.   Consideration was also
given to the information available (although limited) in the litera-
ture on related studies.  Table 1 summarizes the evaluation.

The following techniques were selected for field testing.  A brief
statement of import related to the problem of shallow earth investiga-
tions is included:

Electrical Resistivity

The most widely used geophysical tool for shallow earth investigations.
Many math models and theoretical cases are covered in the literature.

Self-Potential

Literature citings of large self-potentials associated with anthracite
coal spurred the use of this technique.

Airborne Infrared Radiometry

Manifestations of subsurface features due to surface variations in soil
moisture content were sought.  Reconnaissance by detection of water
sources was practical.

Magnetics

High sensitivity equipment used in low background areas theoretically
marginal but worthy of field investigation.

Seismic

Resonance of subsurface cavities reported.  Also, delayed returns,
amplitude "shadows" and amplitude attenuations feasible.

VLF Electromagnetic

Not ordinarily used for fine detail surveys but recent apparent success
at Penn State University for hydrological studies prompted testing.

Induced Polarization

Provides apparent resistivity and self-potential data too.  A poten-
tially powerful exploration tool that has been used almost exclusively
for deep studies.  Advances in understanding the physical phenomena
may make this tool the best of the electrical methods.
                                10

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TABLE 1 SUMMARY OF EVALUATION OF POSSIBLE TECHNIQUES
BPII997

POSSIBLE TECHNIQUES
GEOPHYSICAL
GEOCHEMICAL
THERMAL
RADIOMETRIC
ELECTRIC
MAGNETIC
GRAVITY
SEISMIC
GROUND
WATER
TRANSPORT
SURFACE
WATER
TRANSPORT
TRACERS
THERMAL*
INFRARED
MICROWAVE
RESISTIVITY
SELF-POTENTIAL
INDUCED POLARIZATION
INDUCTIVE (ELECTROMAGNETIC)
SCHMIDT TYPE
FLUX GATE
PRECESSION
TORSION BALANCE
GRAVIMETER
REFLECTION
REFRACTION
SEISMI-ACOUSTIC*
GROUND WATER ANALYSIS
PLANT ANALYSIS
SOIL ANALYSIS
SURFACE WATER ANALYSIS
STREAM SEDIMENT ANALYSIS
CHEMICAL
DYES
RADIOACTIVE ISOTOPES
SUSPENSIONS
BACTERIA
USEFULNESS TO PROGRAM
CORRECTION FACTORS BASED ON TOO MANY UNKNOWNS TO BE OF
PRACTICAL VALUE.
IN CONJUNCTION WITH AERIAL PH.OTOGRAPHY TO ESTABLISH
REGIONAL PICTURE: E.G., DRAINAGE AND FOR FRACTURE
TRACE ANALYSIS
APPLIED USAGE TO SIMILAR PROBLEMS QUESTIONED IN RECENT
TECHNICAL LITERATURE.
THEORETICALLY VERY PROMISING.
MAY BE OF VALUE TO PROBLEM. FIELD TESTING WILL DETERMINE.
THEORETICALLY PROMISING.
RECENT SUCCESS IN MINING EXPLORATION INDICATE MERIT IN
FIELD TESTING.
OLDER TECHNIQUE -- TOO SLOW.
TOO SLOW FOR RECONNAISSANCE. USEFUL FOR BASE STATION.
RAPID, SIMPLE HIGH SENSITIVITY WORTHY OF FIELD TEST.
TOO SLOW FOR RECONNAISSANCE, LOW SENSITIVITY
EXPECTED ANOMALIES TOO SMALL: LARGE CORRECTIONS
NOT AS PROMISING AS REFRACTION BUT WORTHY OF FIELD
EXPERIMENTATION.
THEORETICALLY PROMISING
POTENTIALLY A SIMPLE TECHNIQUE: NOT ENOUGH KNOWN ABOUT
APPLICATIONS.
DETERMINATIONS TO BE MADE WHEN PRACTICAL.
NOT PRACTICAL DUE TO WIDESPREAD SOIL DISRUPTION BY
STRIPPING OPERATIONS.
NOT PRACTICAL DUE TO WIDESPREAD SOIL DISRUPTION BY OPERATIONS.
LOCATION OF POINTS OF INFLUX AND EGRESS OF MINE WATER
ANALYSIS TO FOLLOW STANDARD GEOCHEMICAL RECONNAISSANCE
WHERE PRACTICAL.
LOCATION OF SEEPAGE SOURCES THRU GROUND COVER
LOCATION OF SEEPAGE SOURCES THRU GROUND COVER
NOT FEASIBLE
LOCATION OF SEEPAGE SOURCES THRU GROUNO COVER
NOT FEASIBLE
EVALUATION
FIELD
TEST

X

X
X
X
X


X


X
X




X






STAND
BY


X








X



X



X
X
X

X

DISCARD
X






X
X

X



X

X
X




X

X
*NEW TECHNIQUE
'TO BE FIELD TESTED IF PRIMARY TECHNIQUES ARE NOT SUCCESSFUL.

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Geochemical methods were proposed for use on this problem.   Study of
the sites selected and the applicability of the geochemical approach
led to the conclusion that this effort would be better spent on the
geophysical approaches.   Section XII, beginning on page 81, includes
a discussion of these findings as well as additional discussion of
the geophysical techniques used.

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                            SECTION V

                          SITE SELECTION
This section discusses the eight bituminous coal mine sites that were
selected and used.  One of the sites, the Bitumen #2 coal mine,  has
been lost to future scientific study due to strip mining.  The other
sites are not presently in danger, but it would behoove agencies
interested in solving some of the problems of abandoned deep mines to
consider the utilization of these sites and their data against such
an eventuality.

Prior to any field investigation of geophysical techniques or methods
for detection or location of coal mines, consideration had to be given
to the desired characteristics of the mines to be tested.  It was
established that each mine should differ in geology, topography  and
hydrology as much as practical.  This coverage would insure field test-
ing over a wide range of mine environments.  The rationale for this
approach was based on the fact that each locality could conceivably
require a different sensor technique or combination thereof for  opti-
mum mine detection.

Prior to establishing all the criteria for specific mine sites,  a trip
was made to an operating coal mine, the Rushton Mine, near Philipsburg,
Pennsylvania.  This mine consists of extensive workings in which both
conventional and continuous mining equipment are used.  By studying
the underground workings, a better understanding of the criteria needed
to select a mine was established.  An appreciation for the geometry
and the physical character of the coal mines was also gained which
proved invaluable during the data analysis phase.

Criteria for Mine Selection

The Pennsylvania Department of Environmental Resources provided  numer-
ous mine maps, personal knowledge and observations against which we
were able to weigh our selection criteria.  These criteria included:

Depth of Overburden

Shallow mines were most desirable.  Less than 100 feet of overburden
was preferred.  Thin overburden maximizes the probability of detection
by geophysical means.

Coal Seam Thickness

The thicker the better, again for purposes of maximizing the probability
of detection by geophysical means.
                                13

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Number of Coal Seams Mined

Preference was given to shallow, single seams for simplicity in data
analysis.  It was recognized that multiple mined seams closely spaced
would generally provide a greater physical parameter contrast for most
geophysical measurements but the reduction in ambiguity by studying
single seam mines was thought to be more desirable.

Hydrology

Mines discharging large quantities of acid mine water were sought as a
first choice in that these types of mines are the primary polluters.
Also considered were mines which intermittently discharge acid mine
water, as well as mines which discharge no acid mine water.

Topographic Relief

In order to simplify the analysis of the geophysical data and to mini-
mize topographic corrections of the data, sites of gentle relief were
sought.

Vegetative Cover

In order that the airborne radiometry techniques might be used most
effectively and that field crews have the benefit of true line-of-
sight, the mines should be overlain by open fields.

Access to Site

In that variable quantities of equipment for field measurements re-
quired transporting to the sites, access roads passable to truck traffic
were necessary.

Access to Mine

If the mine had an opening large enough for entry and exit by an ex-
ploration party, it was highly rated.  The purpose of this requirement
was to allow exploration of the mine workings for verification of their
nature, i.e., open, dry/wet to completely collapsed, dry/wet.  This
knowledge was most valuable to the data analysis work.

Absence of Cultural Features

Houses, barns, powerlines, water lines, sewers, roads, cuts and fills,
etc., would influence one or more geophysical methods.  In order to
minimize these sometimes unpredictable "noise" sources, mines were
selected on the basis of the absence of these features.
                                14

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Distance from State College

In order to maximize time spent on field measurements and to minimize
travel  time, mines that are closer to State College were preferred.

Availability of Complete'Maps of Mine Workings

Fundamental to the placement of the traverse lines and the data analysis
is the  knowledge of the location of the mine workings and their nature.

Each of these criteria was subjectively scaled from 0 to 10 points, with
the optimum condition given the value of 10 and sub-optimum conditions
given appropriately lower values.  Table 2 illustrates the numerical
basis and results bf this semi-quantative ranking system.  The mines
listed  in Table 2 are those that were considered worthy of field check-
ing and weighing against our selection criteria after discussion and
study had reduced a much longer list of mines and their maps as provided
by the  Pennsylvania Department of Environmental Resources.

Sites Selected

Table 2 shows in gray tone the eight sites that were selected for study.
Originally only three sites were to be selected and worked.  These were:

     Mills #4
     Bitumen #1
     Bitumen #2

Late in the 1970 field season, after an informal review of project
achievements, it was concluded that it would be desirable to perform
field measurements along traverses over a number of different mine
entries.  This conclusion was based on the apparent success of the
resistivity techniques in detecting drift mine entries through shallow
overburden.  In order to exploit this success, the following additional
sites were selected:

     New Watson (two entries)
     Old Watson (two entries)
     Big Spring (main entry)
     Knowles (main entry)
     Hoover (main entry)

The following sections discuss some of the characteristics of these mines.

Mills #4 Coal Mine

Figure 1 is the site location map for the Mills #4 coal mine.  This mine is
located approximately two miles south of Edendale in Rush Township, Centre
County, Pennsylvania.  Field activities were initiated at this site.

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MINE NAHt
1 BIG SPRING '1
7 RUSHTDN
(OPERATING)
3 CAHT1RIDHT
4 BUCKET LINE
5 CUNARO
. ELLIOT
B KNDBLES «3
1 HABPSTER
8 BEAVER =4
3 STARCH
10 OLD IATSGN
11 ENGLISH CENTER
12 BATSCHLET
., ELLIOT
IJ HILLSIDE
H FLAT RUN ff?
15 SKOOTK HILL »2
16 GRANVIUE «
(OPERATING)
17 ELLIOT. IMLBOR
01 (OPERATING)
18 ELLIOT GIHTER
fll (OPERATING)
19 MILLS *4
20 SPRUCE RUN *2
21 UUREL RUN
22 HOOVER
(SAND* HIOSE)
23 HERB KOHGAN -
(2-OPEHATORS)
!4 FLIT RUN "1
25 GREEN VALLEY
2G BITUMEN *1
27 BITUMEN ^2
IB H£« BATSON


LOCATION
THNSP CDUHTV
HUSH-CENTRE
RUSH-CENTRE
DSCATUR-
CUARF1EID
OECATUR-
CLEAHFIELO
HDRRIS-
CIEARFIELD
HUSH-CENTRE
RUSH-CENTS E
RUSH-CEHTRE
HUSH-CENTRE
RUSH-CENTRE
IESJPOHT-
CUNTON
BESTPDRt-
CL INTON
HUSH-CEHEBE
GHAHAlt-
CLEARflELD
HUSH -CENTRE
RUSH-CEHTRE
JORDAN-
ct EARN eio
GULICH-
CLEARFiELD
HUSH-CENTRE
IE5T SEATIKG-
CL1HTDN
BURNS IDE-
CENTRE
RUSH-CENTflE
RUSH-CENTRE
ERAHAS-
CLEARFIELD
GRAHAM
CLEARFfHLD
IESTPOHT-
CLINTON
HESTPORT
CLINTON
RUSH-CENTRE

NUKER C
VALUE
EXPLANATION

DEPTH OF
OVERBURDEN
[ too id PIS
•
5
10
Id
10
iD
10
Ifl
10
0
10
ID
10
10
8
to
ID
to
0
ID
•
10
10
10
id
10
IG


-' POINT Fan
ErtCH 10
OVER 100
OVERBURDEN

SEAK
THICKNESS
\ 4 10 PIS'
B
B
B
ID
B
ID
10
B
10
ID
10
10
IQ
ID
,10
10
9
3
ID
10
7
8
B
9
B
ID
10
10

-1 POINT FOR
EACH 9 - LESS
THAN 4'
TABLE 2 MINE SITES INSPECTED AND RATED BY SELECTION CRITERIA
NUMBER
OF
SEAMS
MIKED
D
0
ID
ID
1C
,0
- IB.
"~IO
10
ID
10
ID
10
ID
ID
ID
10
It
10
ID
ID
0
10
10
10
10
10
10

prs FOR
ULTIPLE
EAtl ID PTS
OR SINGLE
EAM
HTDROLOGr
(ABUNDANT ACID
MINE IATEH 10 PTS)
j
8
B
B
•
a
4
6
5
3
B
B
G
1
T
8
8
B
5
5
5
B
1
E

B
3
G

ABUNDANCE OF
AJD MINE VATEH
10 PTS
NO flATEft 0 PTS
TOPOGRAPHIC
RELIEF
( 20 IDOD IflPTS)
!
a
i
B
7
5
B
G
7
E
»
B
7
«
7
6
B
B
B
•
"
7
6
B
B

ID
E

1 POINT, FOR EdCH
20 GREATER THAN
70 1000 1 E
20' 1QQTJ' 10 PTS,
40 1000' 9 PTS
ETC
VEGETATION
COVER
7
3
B
T
a
2
5
3
G
'
'
B
B
7
1
9
?
7
B
E
G
6
5
8
5
IG
8
8

DENSE ROODS
0 PTS
!} OPEN 5 PTS
OPEN 10 PTS
ACCESS
TO
SITE
g
!0
10
10
ID
a
a
0
6
ID
7
7
5
E
ID
9
B
8
I
5
10
6
6
8
'
9
3
10

GRADED ON
ACCESiABILITT
BY VEHICLE
ACCESS
TO
SINE
0
ID
0
0
0
0
1
0
0
5
0
0'
, 0
a
Q
ID
tl
0
0
0
'
0
0
0
0
0
7
D

11 TO 10 PTS
GEPENOING ON
ACCESS TO MINE
IORKIWCS
ABSENCE
OF
CULTURAL
FEATURES
10
' a
a
. " a
5
10
ID
10
ID
5
B
B
10
9
B
B
6.
ID
10
9
1
B
10
4
4
'
10
4

HOUSES-PQIERLINES
GRADED BY HO* fEA-
TURES HAY HINDER
FIELD STUDY
DISTANCE
FROM STATE
COLLEGE
10
ID
9
'
9
ID
10
ID
ID
10
6 -,
e
"
B
ID
ID
G
B
10
G
8
IQ
10
ID


6
10

3DHI IOPTS
40V 1 9P]S
SDMI 8PTS
GOHI JPTS

COMPLETE
HAPS
B
1C
7
7
e
B
B
B
B
7
B
B
B
, B
g
B
B
8
IG
!0
10
D
a
°
a
8
ID
10

DETAILED RECEN
HAPS IOPTS
NO MAPS 0 PTS

TDTAL
10 PTS
KAK)
84
77
83
as
19
B
84
79
92
84
83
83
B2
82
ao
98
80
36
BG
79
62
73
BO
61
7B"
8B
93
B4

B5PIS
AN3
60V E
PTIHUK
XCEPT
F R OPEH
A ING
INES

MINES
CONSIDERED
AS POTENTIAL
SITE
YES
NO
(OPERATING)
NO
HO
STRIPPED OVER)
NO
YES
NO
NO
NO
YES
NO
NO
NO
' NO
ND
NO
(OPERATING)
ND
(OPEH4TIHS1
NO
(OPERATING)
YES
HO
ND
YES
NO
HO
NO
YES
YES
YES

CP91G5

-------
                                       SCALE 1 MOOO
                                                                                BP10346
                   KXXJ     L)
                    t i :  i i i
FIG.  1    MILLS #4 COAL MINE  -  LOCATION  MAP,  HOUTZDALE,  PENNSYLVANIA,  7 1/2 QUADRANGLE
                                         -17-

-------
Figure 2 is a copy of the map of the mine workings and related features.
This map is a most valuable aid in our analysis of the data collected.
A great deal of faith is placed in its completeness and accuracy.  This
is so because data collected at distances removed from checkable features,
i.e., mine entries, has to be accurately located in space relative to the
mine workings beneath it and the geometry of the mine workings has to be
known in order for the analysis to be meaningful.

Both mine entries have been sealed with earth and rock.  The right entry
is dry while acid drainage flows through the left entry intermittently.
The site is wooded, although not densely.  This site has the additional
advantage of being remotely located relative to any cultural development
(no power lines nearby; no houses closer than 1 1/2 miles) and is
reasonably close to State College, Pa.  The mine layout, presence of
geologic faults and intermittant acid mine water discharge also contri-
buted to the factors dictating the extensive study of this site.

Table 3 summarizes the geologic section for the site.  This section was
developed from field "investigations and a literature study.

Bitumen #1 and #2

The second and third sites selected and worked were Bitumen #1 and #2.
Figure 3 is the site location map for these sites.  Both mines met the
selection criteria well.

Bitumen #1 is the larger of the mines (see Figure 4).  Only the eastern
portion of Bitumen #1 was studied.  The entries from this part of the
mine were driven from an old stripping highwall.  The cover over this
portion of the mine is a grassy field.  A very shallow overburden, i.e.,
15 to 30 feet, is present and consists primarily of shale.  A continuous
flow of acid water drains from the buried entries.

The Bitumen #2 mine is smaller in extent (reference Figure 5, mine map).
Most of the surveying activity at this site took place along the grid
of lines illustrated in Figure 5.  The overburden is thicker here,
varying from 25 to 60 feet.  The cover is light woods making good sight
distance possible.  The three entries are closely spaced and were driven
from an old stripping highwall as was the case at Bitumen //I.  A crawl-
way exists into the mine from the "C" entry which is partially open.
This access offered an opportunity to explore the mine workings.  The
exploration was undertaken in order to determine their character, an
important ingredient to any full interpretation of the geophysical data.
It was observed that the drifts are generally open.  The roof rock has
held up well with a few exceptions.  The workings are primarily dry.
The mine is characterized by a low-saddle area in which pooling of acid
water takes place.  A deep ditch cut through the underclay in the "B"
main allows this water to seep into the underlying strata.  As the result,
                                18

-------
    SCALE
I     I     I
0'   100' 200'



                                                                                                /
                                                I^i^»
                                                wW^

                                                                                                            f
                                                                                                          I

        FIG.  2   MAP OF THE MILLS  NO.  4 MINE OPERATED BY WALLIN AND CHRISTROFF,RUSH  TOWNSHIP,  CENTRE  COUNTY,  PA.
                 (November 21, 1951, Bernard  Lucas  --  Engineer)
BPI0397

-------
TABLE 3 GENERALIZED STRATI GRAPHI C SECTION FOR THE "A" SEAM COALS OF THE PHILIPSBURG-
HOUTZDALE SYNCLINAL BASIN
SECTION
UPPER ALLEGHENY
GROUP
LOWER ALLEGHENY GROUP
Q_
0
en
CD
UJ
V)
1—
0
0-
PENNSYL
"*" MISSISS
( bounda
d i spu t
CD Z
zo
Z t—
II
t— 0
— U-
z
o
0
u_
z
o
CE
O
1
1
MERCER FORMATION
1
1
VANIAN
1 PPIAN
ry in
8)
THICKNESS
(FEET)
0
>40
— 15
4^-5
1 — '6
>30
3-5
~20
3-5
3-5
15-50
0-25
1 3
5-25
	 75-100 	
LITHOLOGY
NOT PRESENT OVER MINE AREA
MEDIUM TO MASSIVE SANDSTONE ( CROSSBEDD ING)
FISSILE GRAY SILTY SHALE (HAMDEN SHALE)
LOWER KITTANNING COAL (B)
UNDERCLAY
SUBGRAYWACKE SANDSTONE (LOWER KITTANNING SS)
FISSILE BLACK SILTY SHALE CONTAINING CARBONIZED PLANT FILMS
CLARION SS.BUFF AND GRAY-WHITE SUBGRAYWACKE

| CLARION 1 ,2,3 (A) |
UNDERCLAY, SOFT BLUE, IMPURE
HOMEWOOD SANDSTONE
MERCER SHALE
MERCER COAL (DIRTY)
UNDERCLAY
	 CO_NO_QUE_NE_SSj_NG_ S_AND_STONE (?) GRAY CHANNEL FILLING
POCONO SANDSTONE WHITE
AP10091
20

-------
                                           SCALE 1 24000
                                                                                               BP11Q13
                                  1000     ?000    MM    4000    5000    6000    TOOO FEF1
                                     CONTOUR  INTERVAL 20 FEET
                                        DATUM is MEAN SEA LEVEL
FIG. 3    BITUMEN #1 AND  #2  COAL MINES  -  LOCATION  MAP,  KEATING AND RENOVO WEST,  PENNSYLVANIA
          7 1/2'  QUADRANGLE
                                              -21-

-------
                                                        '///>' 'I/I -:"nF       ,
                                                        •h ,','^f^Lr^    '
                                                          «^^5)V^

FIG. 4  MAP OF THE BITUMEN #1 COAL MINE OPERATED BY HARRY S. BATSCHELET,  CLINTON COUNTY,  PENNSYLVANIA
       (FEBRUARY 1,  1951, F. A.  BOBANICK - ENGINEER)

-------
                        ^r
Pfl STftTE FORtST t W«TER5
                   "
                                                        0'              100'            200'            300'

        FIG. 5  MAP OF THE BITUMEN #2 COAL MINE OPERATED BY HARRY S. BATSCHELET, CLINTON COUNTY, PENNSYLVANIA [SEPTEMBER 15, 1954, F.A. BOBANICK • ENGINEER)

-------
this mine does not have an acid water drainage problem.   As excellent
a site as Bitumen #2 was, it was lost to a strip mining  operation.
Stripping began over a portion of the mine area in late  March 1971.
This risk is present for all of the sites studied.

A complete statigraphic section is given in Table 4 for  the Bitumen
mines and the overlying strata.  This section was derived from field
investigations and a study of the available literature.

Watsons, Big Spring, Knowles and Hoover Coal Mines

Only the entries were studied at these mines.  Traverses were usually
laid-out at right angles to the drift entries.  A number of different
techniques were tested to determine their detection effectiveness.  The
mine locations are illustrated in Figure 6.

     New Watson and Old Watson Mines

     Figure 7 is a copy of the mine map for these two mines.   As may
     be noted, the mines are very close to each other.  Beneath the
     traverses the overburden is no more than 20 feet maximum,
     generally less, for each of the entries

     The right entry of the New Watson is earthen sealed and dry.  The
     left entry is covered by sandstone rubble and intermittently dis-
     charges acid mine water.  The right entry of the Old Watson mine
     is open to the mine workings.  No drainage comes out of  this entry
     as the coal seam dips into the hillside at this particular point.
     The middle entry at the Old Watson was also studied.  This entry
     is near a road haulageway.  As the result of this location, it
     was tightly filled with soil and rock for some distance back along
     the drift.

     Big Spring Coal Mine

     The Big Spring coal mine is shown in Figure 8.  The main entry is
     sealed by a massive rock fall.  This seal prevents  visual observa-
     tion of the drift.  No acid water drainage or evidence of drainage
     is observable at the main entry although the mine "breathes" through
     this barrier.  Apparently, the seam dips away from  this entry.  The
     strata directly above the seam consists of thick bedded sandstone.
     The traverse line was located on the hillside 25 feet over the roof
     of the drift entry.  The fan entry underlies part of the traverse
     line.

     Knowles Coal Mine

     Figure 9 illustrates a copy of the mine map.  Note  that the entry
     is very close to the entry of the Harpster mine.  The Harpster mine
                                 24

-------

SYSTEM
/— ^





^
['
c/o




Z
=»
>-
z
UJ




TABLE
GROUP
^-/•^-^-^.






GROUP














4 STRATIGRAPHIC
FORMATION
	 -^-~^^-^.





Kl TTANNI NG
FORMAT 1 ON














SECTION
THICKNESS
(FEET)
*^~~~—
"' 30



8
" 4
to 7





12




"- 2


51
5%
•' 3
FOR THE BITUMEN COAL
SYMBOL
• - '. '- . -
'.''.•'
• — •- ; •=• — -— . 	 • 	 ^^:
f-.- • j— ' • V. '•"••'• '•.•':'.''--::'
^^m
UNDERCLAY
MINES AREA
AP11007
BRIEF DESCRIPTION
. EROSION
^-^~"\^—^/^^
SURFACE
SUBGRAYWACKE CAPPING HILL
'' R 1 M OF HIGHWALL EXPOSURE
\

SOIL, SILTY SHALE & S.S. BLOCKS
:SILTY SHALE





GRAY FISSILE SHALE



^, 	
GRAY/BROWN SILTY SHALE
*^**^^^

BLACK SILTSTONE AND SHALE
LOWER KITTANNING COAL (B)
EXPOSED IN TRENCH IN MINE
FLOOR
25

-------
FIG.  6   LOCATION MAP  FOR  THE  NEW  KATSON,  OLD  KATSON.  BIG  SPRING  #1.  KNOM.ES  AND  HOOVER COAL
         MINES -- PHILIPSBURG  AND  SANDY  RIDGE,  PENNSYLVANIA.  7-1/2' QUADRANGLES
                                                                                                     BPII362
                                            -26-

-------
FIG  7   MAP OF PART OF  THE OLD  AND NE»  KIATSON  MINES.  OPERATED  BY  CLEM KATSON,  PHILIPSBURG,  PA  (NOVEMBER 4,  1951,
         G.E. DUNKLE-ENGINEER)
                                                                                                                 BPII826
                                                     -27-

-------
-28-

-------
      SCALE
  100'
200'
300'
FIG. 9  MAP OF PART OF THE KNOWLES MINE, OPERATED BY THE ELLIOT COAL MINING CO., RUSH TOWNSHIP, CENTRE COUNTY, PA.
       [OCTOBER 31, 1968, BERNARD LUCAS ASSOC. - ENGINEER)

-------
could make another test site.  The overburden beneath the traverse
line is 15 feet thick and consists of shale.   The entry is open
although a considerable quantity of shale has fallen from the roof.
No drainage comes from this entry as the entry cuts down through
the overburden to the seam.

Hoover Mine

The Hoover coal mine main entry is sealed by  earth and rock.   The
seal is not water tight, however, in that mine drainage is discharged
in the spring.  Although a mine map was thought to be available when
work began on this mine, a subsequent check with the Pennsylvania
Department of Environmental Resources determined that this map was
accidentally destroyed by fire several years  ago.
                           30

-------
                            SECTION VI

                        FIELD MEASUREMENTS
Table 5 indicates the information collected at the various mine sites.
Reference will not be made to this tabulation in the following sections.
The following sections discuss the various measurement methods briefly
and in general for all sites.

Surveying

Transit and rod surveying was the first activity performed at the sites.
A base control station was defined and located near one of the mine
entries.  A control line and additional control stations were laid-in
so that accurate locational control of the various geophysical travetses
could be maintained relative to the mine workings and other features as
defined by the mine map.  A transit, model 2-CF-30 (Warren-Knight Co.,
Philadelphia, Pennsylvania), and stadia, Philadelphia Type E (Keuffel
and Esser Co., Morristown, New Jersey) were used for this work.

Plane Table

Plane-Table topographic mapping of the surface over the mines was the
second activity at each of the sites.  The elevation and location data
obtained from this technique was taken in a more comprehensive manner
for certain of the sites than is required in ordinary practice.  This
was done so that the data could be fed into HRB-Singer's IBM 360-40
computer and operated on by our STAMPEDE program.  This operation pro-
vided us with a computer generated, topographic contour map which
could be positively checked against our field generated, topographic
contour map.  This capability will be discussed in greater detail in
the discussion of computer analysis under SECTION VII.

The topographic contour map permits the estimation of the thickness of
the overburden above the coal seam.  Naturally- some knowledge of the
dip of the coal is necessary to accomplish this with accur-acy.  Most
of the coal seams are flat lying or have a very shallow dip.

Except for the Mills #4 mine, only the portion of the mine of inte'rest
was mapped.  At the Mills #4, the entire mine was mapped.

The alidade used was made by the Gurley Engineering Instruments Co. of
Troy, New York.

Altimeter
To establish the elevation of the base control station at the mines, a
Terra Survey Altimeter, Model SA-1  (American Paulin System, Los Angeles,
California) was used.  This instrument is accurate to 2 feet and is of
                                31

-------
TABLE 5 TABULATION OF INFORMATION COLLECTED AT MINE SITES


DC
IS
TRANSIT * BOD SURVEYING
PLANE-TABLE SURVEYING
CONSTANT DEPTH
^C TRAVERSE
^ DEPTH PROFILES
SELF-POTENTIAL
AIRBORNE INFRARED
RADIOMETRY
TOTAL FIELD MAGNETICS
MAGNETIC GRADIDUETRY
SEISMIC REFRACTION
SEISMIC REFLECTION
VLF ELECTROMAGNETIC
INDUCED POLARIZATION
COAL MINE SITES AND COVERAGE OBTAINED
MINES ANO ENTRIES STUDIED
MILLS #4
BASE STATION 8
SEVEN PRIMARY
STATIONS
SCALE 1 50'
5' CONTOUR
INTERVAL
16.200'"
5. 800' *
25,675'*
1000' 2.000' S
3000' ABOVE
TERRAIN
10.080'*
400'*


4.990'*
4,975'*
BITUMEN #1

SCALE T'lOO'
5' CONTOUR
INTERVAL
1.980'*

1.980'*
200', 500' £
1000' ABOVE
TERRAIN
,.980'*



1,980'*

BITUMEN »2
TEN TRAVERSE(GRID)
LINES
SCALE l"=100'
51 CONTOUR
INTERVAL

3,000'*
3,000'*
200'. 500' £
1000' ABOVE
TERRAIN
3,000'*

1.405'*
1.405'*


ENTRIES STUDIED
NEW WATSON

SCALE 1 '=100'
5' CONTOUR
INTERVAL
,.110'*

370'*
1000' ABOVE
TERRAIN
370'*
IBS'*


370'«
300'*
OLD WATSON

SCALE 1 =100'
5' CONTOUR
INTERVAL
1,260'*

420'*
1000' ABOVE
TERRAIN
420'*
150'*


300'*
240'*
BIG SPRING

SCALE l"=25'
5' CONTOUR
INTERVAL
..650'*
450'*
340'*
1000' ABOVE
TERRAIN
340'*





KNOWLES
TRAVERSE ALIGNMENT
CHECKED AGAINST
DRIFT ENTRY ALIGN-
MENT
SCALE l"=100'
5' CONTOOR
INTERVAL
2.935'*
300'*
600'*
1000' ABOVE
TERRAIN
600'*
215*


600'*
300'*
HOOVER

SCALE l"=50'
5' CONTOUR
INTERVAL
2.895'*

430'*
1000' ABOVE
TERRAIN
430'*





REMARKS
ASE STATION ELEVATIONS
BTAINED WITH ANEROID
AROMETRIC ALTIMETER
ELATIVE TO LOCAL BENCH
ARKS
ERTINENT PHYSICAL
EATURES SKETCHED ON
LANE TABLE MAPS
ENNER ELECTRODE
ONFIGURATION USED
ONTINUOUSLY.LEE
LECTRODE CONFIGURATION
SED OCCASIONALLY
IURNAL AND LONGER
ERM FLUCTUATIONS
MONITORED FOR CORREC-
ION PURPOSES.
nSB (3-5 MICRONS).
g Cd:Te (8-14 MICRONS).
8 Ge:Hg (8-14 MICRONS),
ETECTORS USED AT VAR-
OUS TIMES.
DIURNAL FLUCTATIONS
MONITORED EITHER
HOURLY OR CONTINUOUSLY
GRADIOUETER "BUCKS
OUT" NOISE DUE TO
FLUCTUATIONS
ONLY USED WHERE NATURE
OF WORKINGS KNOWN DUE
TO EXPLORATION.
DEEP REFLECTION
HORIZONS ONLY.
IN-PHASE AND QUADRATURE
COMPONENT MEASURED.
STATION NAA. CUTLER,
MAINE. 17.8 kHz, 100 kN.
PRIMARY FIELD SOURCE
DIPOLE-DIPOLE ELECTRODE
CONFIGURATION USED
EXCLUSIVELY.
•SUM OF ALL TRAVERSES BP12282

-------
the aneroid barometric type.  Two or three  (varied with site) complete
altimeter observations were made in as many days in order to establish
an average reading for the base stations.  Each observation was performed
in the following manner while enroute to the mine site:  (1) the altimeter
was set up and read at a U. S. Geological Survey bench mark (nearest
locatable) and at an intermediate check-point, when possible, (2) the
altimeter was then moved to the base station at the mine and the reading
recorded, (3) the reverse order of these steps was followed while depart-
ing the area in the evening.  Following two or three complete cycles of
altimeter data collection, averages were computed for the base station
at the mines.

Electrical Resistivity

The electrical resistivity method was the first measurement technique
to be put to use.  An earth resistivity meter, model ER-2 (Geophysical
Specialties, Minneapolis, Minnesota) was used in these studies.   Depth
profiling was performed over selected portions of the mines and over
selected areas in which there were no mines.  These profiles allowed
the characterization of the electrical properties of the rock strata.
The Wenner (standard) electrode configuration was used as was the Lee
partitioning method.  The Wenner configuration supplied data that was
reduced to standard units, plotted and compared with theoretical curves
(Money and Wetzel, 1956).

The Lee partitioning method provided some information on the electrical
continuity of the rock strata across the entire electrode spread.  This
information did not prove to be helpful in the interpretation of the
data obtained from the Wenner configuration, and was discarded after
work at the Mills #4 mine.

Constant electrode spacing or constant depth traverses were also run.
The Wenner electrode configuration was exclusively used for these
traverses.  The objective of this search procedure was to locate the
mined sections and other features (faults, fracture traces, etc.) that
provide water avenues into the mines.

Self-Potential

Self-potential surveys were run concurrent with the plane-table survey-
ing at the Mills #4 site.  All other sites were surveyed by single-
line traverse or by grid coverage.  At the Mills mine the reference
electrode was maintained beneath the centrally located plane-table
while the other electrode was moved in a radial manner about the refer-
ence point.   The initial equipment used was an earth self-potential
potentiometer (McPhar Geophysics, Toronto, Canada) which uses an
acoustic null circuit.   The electrodes are non-polarizing,  porous
ceramic pots containing a super-saturated copper sulfate solution which
surrounds a copper electrode.  The McPhar device developed null problems
                                 33

-------
and was committed to an early retirement.  A millivolt-potentiometer,
model 8686 (Leeds and Northrup, North Wales, Pennsylvania) was
successfully used for the remainder of the self-potential measure-
ments.  Control stations were monitored for diurnal and longer term
variations.

The objective of these measurements was to measure the natural/spon-
taneous voltages developed in the vicinity of the mines and to
establish if differences appear that may be related to  chemical/
electrical activity of the mined areas.

Radiometry

Airborne infrared overflights were made at the sites under different
operating conditions.  The following parameters were varied:  date,
time of day, altitude, detector and system (RECONOFAX IV, X, XIIIA
and AR-2 radiometer made by HRB-Singer, Inc., State College, Pennsyl-
vania) .

The objective of varying these parameters was the determination of
the optimum conditions for detection of the mine workings or mine
related features.

Surface measurements of temperature and soil moisture were made at
some of the overflown sites.  Supporting weather data was obtained from
The Pennsylvania State University weather station for the overflights.

Magnetics

The object of the magnetic measurements was to detect variations in
the earth's magnetic field that could be related to the mine workings.

Magnetometer experiments were initiated in July 1970.  An HRB-Singer
in-house developed, portable, nuclear precession, total field magnet-
ometer was the data collection unit.  The instrument has a sensitivity
of +1 gamma and possesses a direct digital readout in gammas.  Cycle
rate on the readout is 2 seconds.  The sensor is omnidirectional and,
hence, requires no  orientational setup.

A second nuclear precession magnetometer with a continuous record
capability was occasionally used for control station recording.  This
magnetometer, although built by HRB-Singer, was provided by the Naval
Ordnance Systems Command, Code ORD-0534, Washington, D. C.

A third unit, a magnetic gradiometer, was also field tested and eval-
uated.  This unit functions as a differential magnetometer.  Two field
sensors respond to the earth's field, the signals are electronically
subtracted and a difference readout is obtained.  The two sensors are
capable of being placed any distance apart but for project purposes
they were spaced five or ten feet.  The sensitivity is rated at +0.2
                                 34

-------
gamma.  The cycle rate varies from 3.0 seconds on the coarse scale to
0.3 seconds on the fine scale.  This instrument was provided by Mr.
Nevin Davis of State College, Pennsylvania.

In order to correct for diurnal drift of the earth's magnetic field,
two techniques were used at different times.  The first method requires
that the survey instrument be removed to a control station and the
magnetic field and time recorded approximately once every hour.  From
a plot of this record, the field drift can be obtained and the survey
data corrected accordingly.  The second method employs the continuous
recording magnetometer which is set up at the control station.  The
record is studied for drift and the appropriate corrections are made.
The gradiometer has the advantage of not requiring drift correction
since it merely measures the magnetic field difference.

Initially the control station was located in an area removed from any
mine workings.  It was determined shortly thereafter that removal was
not necessary since the presence of the mine beneath the control sta-
tion did not cause any time varient field effects.

Seismic

These experiments were directed at (1) determining whether resonance
could be induced in coal mines and whether it could be used for detect-
ing them a-nd (2)- determining the presence/location of coal mines by
(a) 'delayed returns,. .(b) "shadow" zones, or (c) amplitude attenuations.

All seismic experimentation was done at the Bitumen #2 coal mine site.

First a few words of introduction with regard to shallow earth seismic
field procedures.  The arrangement of the detectors may be varied in a
multitude of ways.  An effective arrangement for a relatively rapid
reconnaissance of a potentially mined-out area is the conventional or
straight-line spread in which the detectors are arranged in a single
straight line from the point of the energy source.  In this case, the
distance from the point of the energy source and the first detector
should be approximately equal .to the assumed or measured depth of
overburden.  The detector spacing should be some smaller distance,
i.e., ten feet, depending on the definition sought.  This detector
spread was primarily used in our studies.

A second arrangement of detectors that is suited for detailed recon-
naissance of a given mine site or more specifically, the delineation
of a subsurface feature (drift, room, fault, etc.) is the fan-spread.
In this arrangement the detectors are spread in a semicircular fashion
around the point of the energy source.  The point of the energy source
being equidistant to each of the detectors.  This arrangement was also
used.
                                  35

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Four different seismic lines were laid-in over the Bitumen #2 coal
mine.  The first line was laid-in so that it was parallel to and
directly above the "B" entry.  The second line started at the high
wall point directly over the "B" entry and went 80 feet along a
heading of N 23°W.  This line would then be over a well-worked
section of the mine.  The other two lines were established along
grid lines #8 and #1, respectively.  Line #8 transects a portion
of the easterly trending drift.  Line #1 should provide a control
check against which the other records could be compared.  No mining
activity is shown on the mine map to have taken place under line #1.

A total of 28 records were obtained along these survey lines.  Seven-
teen records were obtained from the array over the "B" entry including
two modified fan shots.  This line was heavily investigated since we
were attempting to observe the cavity resonance phenomena reported by
Watkins, Godson, and Watson  (1967).  Four records were obtained along
the line bearing N 23°W.  Four records were obtained along line #8.
Three records were obtained along line #1.

A 12-trace, portable, refraction seismigraph, model 506 (Century
Geophysical Corporation, Tulsa, Oklahoma), was used as the data col-
lection instrument.

VLF Electromagnetic

VLF  (very low frequency) electromagnetic surveys were initiated in
May 1971.  This instrument, model EM16, is manufactured by Geonics,
Ltd., Toronto, Canada and was made available by lease through the
Geophysical Instrument and Supply Company, Denver, Colorado.  Briefly,
this instrument utilizes uniform radio frequency fields generated by
a network of U. S. Navy stations that operate in the very low fre-
quency band.  Subsurface discontinuities in electrical properties
cause inductive field effects which are measured by the receiver
instrument at the surface.

The objective for this study was to determine whether these secondary
fields are generated or attenuated by mined areas and, if so, whether
they are of sufficient magnitude to be measurable.

Traverse lines were run exclusively.  Station intervals were either
five or ten feet.

Induced Polarization

Induced Polarization (IP) surveys were conducted over selected traverse
lines used initially for the resistivity surveys.  The equipment used
for the IP surveys included a Mark 4 IP Sender and a GEOEX Mark 4C
Multiple Frequency IP Receiver (Heinrichs Geoexploration Company,
Tucson, Arizona).  A portable Briggs and Stratton gasoline engine,
coupled to a 120 VAC, 400 cycle generator, supplied the power to the
IP Sender.  The output current was sent into ground via two 24 inch

                                 36

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steel electrodes that were driven into 18 inch deep pits which
were previously filled with a brine solution that had soaked into
the ground.  Two non-polarizing electrodes containing a super-
saturated copper sulfate solution were used to receive the signals.
A dipole-dipole electrode configuration was used exclusively.

It was hoped that IP effects would be related to mined areas, un-
mined areas or features related to mining.

Soil Moisture

In order to determine if soil moisture variations can be related
to shallow mine features, five soil moisture traverses were run at
right angles to the main entry at the Knowles coal mine during the
period of airborne infrared overflights of 14 April 1971.  The
traverses were spaced approximately 50 feet apart along the main
entry.  Station interval along each traverse line was 5 feet.  The
instrument used was a nuclear moisture density meter manufactured
by Soil Test, Inc.,  Evanston,  Illinois.

Investigation of the Workings of the Bitumen it2 Coal Mine

On 17 November, a detailed exploration of the workings of the Bitumen
#2 coal mine was undertaken.  The objective of this study was to
observe the state of the mine workings (collapsed, open, etc.), the
drainage of the mine (Where does the water come from?  Where does it
go?) and the geology of the roof rock beneath the coal seam.

Dave Milward, Pennsylvania Department of Environmental Resources,
led the exploration group.  His experience and knowledge of coal mines
insured a safe undertaking.

With regard to the state of the mine workings, the mine was observed
to be almost completely open and clear.  Only two rock falls were
observed.

The general condition of the mine was good.  The workings are open
and the timbering is reasonably good even though the mine has been
abandoned for approximately twenty years.  Water pools fill low
points in the mine.  The source of the water is rainfall.  Rain water
infiltrates the soil and then seeps through the minor joints and
fractures in the rock overburden to drip into the mine.

Thin, pencil-like stalactites composed of hydrous iron oxide minerals
are found along the intercept of the minor joints and fractures with
the roof of the mine.  The rain water dissolves minerals as it perco-
lates through the overburden.  These minerals are recrystallized at
these "drip points" forming the stalactites.  An interesting aspect
related to the composition of these stalactites is that it brings up
                                37

-------
the question of the contribution of the iron leached from the over-
burden to the total iron contribution in acid mine drainage.  These
stalactites are numerous and lengthy indicating that a considerable
amount of iron minerals have been leached from the overburden since
this mine was opened.  Obviously the composition of the overburden,
quantity and character of the sulfide mineralization in the coal,
fracturing in the overburden, nature of the mine workings and other
factors will affect this contribution.

The Bitumen #2 coal mine has a natural low area due to an undulation
in the topography of the coal seam.  This low area is apparently large
enough to pool all of the mine water accumulated from rain water
infiltration.  (The mine is not deep enough to intersect the ground
water table.)  A large ditch running through the low area along the
"B" main cuts through the thick (approximately three feet) underclay.
This ditch provides access for the water to the permeable rock
strata beneath the compact underclay.   This provision for getting
rid of the water and the good fortune of having a natural pool area
insures against this mine having an acid mine water drainage problem.

Geologic Field Work

Geologic field reconnaissance was performed at all of the field sites.
Detailed stratigraphic sections were developed for the areas.   This
work was undertaken in that a fundamental knowledge of the local geo-
logy is basic to any geophysical interpretation.
                                38

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                           SECTION VII

              DATA ANALYSIS AND TECHNIQUE EVALUATION
Electrical Resistivity

Mills #4 Mine

Figure 10 illustrates the location of the resistivity depth profile
lines and their respective results.  The field data was plotted to
a standardized log-log format and compared with1 Money and Wetzel
curves.  This comparison analysis yielded a correlation with the
theoretical 4-layer case. ' The apparent resistivities in ohm-feet
and the depth of each layer are illustrated in the sections adja-
cent to each profile line.  The estimated top of the coal seam is
noted by'the black arrow.  The coal' seam location is estimated
from the plane-table topographic map and the projected dip of the
coal seam.

The ratio between the electrode spacing used in the Wehner spread
and the apparent depth of penetration is dependent on the resis-
tivities of the local rock strata.  A generalized ratio  can be
developed about this site from the data presented in Figure 10.
                    .       1.2   :   (electrode spacing)
This generalized ratio is:  —:	-,	—,  ., *	—~—~.—~\ •
     5                       1     (apparent depth penetration)
This ratio was of interest when the constant depth traverses were
run.  Once the topographic data revealed the depth to the mine work-
ings (coal seam) the ratio factor could be applied to establish the
electrode spacing required to probe to that depth.

The depth profile lines that are  in the southern portion of Figure
10 are exclusively over areas in which there are no mine workings or
faults.  The results from these profiles provide the basis for com-
paring and studying the depth profiles over portions of the mine
workings and the known faults.  It is apparent that there were no
well-defined boundaries or breaks in the resistivity 4-layer section
that could be correlated with the mine workings.

Constant depth/constant electrode spacing traverses were run along
selected lines over the mine area and the control area.  These lines
included all the lines covered by the depth profiling and some addi-
tional ones.

The topographic maps were used to determine the depth of the mine work-
ings along a given line.  This depth was multiplied by the scale factor
(as determined from the depth profiling) to obtain the electrode
spacing required for that particular line.  Usually, several different
electrode spacings were run along a given line for comparison
                                39

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LEGEND
O SURVEY POINTS
O DEPTH PROFILE STATIONS
*- COAL (TOPt ESI DEPTH
4__ POINTS TOIARD SECTION
ASSUMED STRATIGRAPHIC SECTION
BO-1
50-
40-
FE£7 3
-1 -

^>^
K
SANOSTONE iSSi
SHALE iSh)
S1NOSTONE (SS)
i_COItL (Al
UMDEKCLAY
0 50 10, 20
LATERAL SCALE |FT|
VERTICJU
SCALE |FT]

• 20
10
J-M
                  \--~-
FIG. 10  LOCATION OF THE ELECTRICAL RESISTIVITY DEPTH PROFILE STATIONS, LAYER BOUNDRIES
       AND APPARENT RESISTIVITY [OHM FEET] OF THE LAYERS AT THE MILLS  #4 MINE
                                     -40-

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purposes and to bracket the mine workings,'lest there be strata above
or below the mine  (underclay, for example) whose electrical character-
istics had been altered by the mining process and, hence, would pro-
vide the all important "indicator" horizon.

Figure 11 shows a number of data plots for constant depth traverses
over the two mine entries.  These traverses show some of our most
successful data.  Notice the sharp decreases in resistivity over
both entries at the 30 and 35 foot spacing traverses.  The right
entry (sealed, no water flow) also shows sharp decreases for the 20
and 25 foot spacing traverses.  The entry with the water flow (left
entry), interestingly, shows less of a decrease in resistivity than
the entry that is apparently dry.

In Figure 12 three different constant depth traverse lines are plotted
relative to the portion of the mine that they overlie.  Various elec-
trode spacings were run along each of these lines.  Data from several
of these different spacings are plotted adjacent to their respective
traverse lines.

There is no consistant correlation between the mine workings and the
resistivity traverse data.  One notable exception is the westernmost
traverse line as it crosses the westernmost fault.  All of the elec-
trode spacings used along this line revealed a decrease in resistivity
near the mine map plot of the fault.  This decrease would be expected
for a water movement avenue containing a conductive medium (water).

Bitumen #1 Coal Mine

Constant depth traverses were run along each of the survey lines over
Bitumen //I.  Each of these traverses are underlain by shallow over-
burden (i.e., 20 to 30 feet).  Figures 13 and 14 illustrate apparent
resistivity relative to the mine features as indicated by the mine
map.  No correlation between the resistivity data and the mine work-
ings is apparent.  The lack of correlation between the slump zones
and the mine workings indicates a number of problems that may include
the following factors, wholly or in part:  the mine map may not be
exact, that there is a lack of correlation between the plane-table
survey and the mine map due to tie-in error and/or the plane-table
maps are inaccurate.  The lack of apparent correlation between the
traverse data and the mine is discouraging.

Bitumen #2 Coal Mine

Depth profiles were run along all of the grid lines.  Lines 11 and 12
are close to paralleling the topographic contours of the site, hence,
their results were expected to differ somewhat from that of grid lines
#1 through #10 due to the influence of the additional strata beneath
the up-slope side of the electrode configuration for the latter grid
                               41

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    95 -i
    85  -
    75  -
    65  -
    55
                                      LEFT ENTRY
                                    WET:  20 TO 125
                                        GAL/MIN
EAST    0


      FIG. 11
       50
 I
100
     150              200
RELATIVE DISTANCE  (FEET)
                                                                                                           ELECTRODE
                                                                                                           SPACING
CONSTANT DEPTH RESISTIVITY  PROFILES OVER  THE MILLS
OF OVERBURDEN ;   31  FEET
250
                                      4  MINE ENTRIES,  DEPTH
300    WEST
                                                                                                                BP10095

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                  SO     100           -200
                    SCALE IN FEET
8000
5000
4000
              ..
                                                                                                               TRAVERSE LIHF
                                                                                                                                                                     300040005000 6010
            FIG. 12   RESISTIVITY TRAVERSE DATA AT SELECTED 'a' SPACINGS |feet| RELATIVE TO THE  MILLS #4  MINE WORKINGS [apparent  resistivity units  =  ohm feet]

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                                                                                                                            MILLIVOLTS
                                                                                                TOTAL MAGNETIC FIELD
                                                             I—  57370

                                                                 57360

                                                             -  57350  GAMMA

                                                                 57340

                                                             —  57330

                                                             —  573BO
                                                                                            APPARENT RESISTIVITY
                                                                                            (20' ELECTRODE
                                                                                            SPACING)
                      SLUMP SLUMP  SLUMP
                                                             SLUMP
                                                                                      SLUMP
                                                                                                       SLUMP
                                                                     tsss issf  sss
970'
        900
                    800
                               700
                                           600
500
              400
                       300
                                      200
100'
                                                       SCALE. HORIZ. 1   - 100'
                                                             VERT. NONE

                                                             MINED AREA
                                                             [— 4000

                                                                 3500

                                                              — 3000

                                                              — 2500

                                                              — 2000

                                                              — 1500
                                                                                                                              OHM-FEET
                                                                                                                       OVERBURDEN -  20

                                                                                                                       MINE LEVEL
                                                             0  (NORTH)
               Fid 13   BITUMEN #1  COAL  MINE SURVEY  LINE #1;  CROSS  SECTIONWITH  RESITIVITY, MAGNETICS AND  SELF-
                        POTENTIAL  TRAVERSE  DATA
                                                                                                                                AP11259

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                                                                                                        - +60
                                                                                                        ~ +50
                                                                                                        - +40
                                                                                                           +30
                                                                                                        !- -"-20
                                                                                                           + 10
                                                                                                             0
                                                                                                        1	10
                                                                                                                   MILLIVOLTS
                                                                                   TOTAL  MAGNETIC FIELD
                                                                                                           57370
                                                                                                        — 57360
                                                                                                        - 57350  GAMMA
                                                                                                        — 57340
                                                                                                           57330
                                                                                  APPARENT RESISTIVITY
                                                                                  (30' ELECTRODE
                                                                                  SPACING)
900
              800
                       700
                                     600
                                              500
                                                          400
                                                                     300
                                                                              200
                                                                                               100
                                               SCALE: HORIZ.  l" =  100'
                                                     VERT.  NONE
                                                     MINED  AREA
                                                                                                           3500
                                                                                                        - 3000
                                                                                                           2500
                                                                                                        - 2000   OHM-FEET
                                                                                                        0'  (NORTH)
FIG. 14    BITUMEN #1,  COAL MINE SURVEY  LINE #2,  CROSS  SECTION!
           TRAVERSE DATA
                                                                      ITH RESISTIVITY,  MAGNETIC  AND SELF-POTENTIAL
                                                                                                                          AP11258

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lines.  The data from lines #11 and #12 indicate that the "topographic
effect" need not be considered an influence on the grid lines #1 through
#10.

Grid lines #1 through #10 progress from an area free of mining influence
(line #1) to an area almost totally undermined (line #10).  It was
expected that a progressive variation in the character of the curves
would be observed.  This variation was not observed.

New Watson, Old Watson, and Big Spring #1 Coal Mines

The electrical resistivity data collected over the drift mine entries
was plotted and analyzed.  Figures 15, 16 and 17 illustrate some of
the typical data plots obtained.  Figure 15 illustrates the resistivity
and magnetics data obtained over the New Watson entries.  The resis-
tivity data does not indicate the presence of the entries.  The right
entry shows generally higher resistivity values than the left; however,
the background trend is toward higher resistivity values in this loca-
tion.  Higher resistivity values would be expected for an open, dry
non-conductive drift.  This does not appear to be the case here as the
entrance has a tight earthen seal.  However, it should be noted that
the traverse line, although at almost right angles to the heading of
the entries, is approximately twenty-five feet back from the entry
points.

The data illustrated in Figure 16 is more encouraging.  Notice the
decrease in resistivity for each electrode spacing associated with the
location of the drift entry.  The overburden thickness is only about
fifteen feet here.  The peak of the resistivity minima is slightly
to the left of the indicated location of the entry.  This occurs
because the drift bears to the left as it goes into the hillside.  The
decrease in resistivity is expected for an entry which has a conducting
media present, such as acid mine water.  However, this entry is open
and, although the bottom of the mine is wet, there is no accumulation
of water.

Figure 17 illustrates the resistivity plots over the Big Spring #1
coal mine main entry.  The overburden is about twenty feet over the
main entry nd thirty-five feet over the fan 'entry.  The overburden
consists primarily of massive sandstone.  The 20, 25, and 30 foot
electrode spacing traverses show a fair sized anomaly, whereas, the
35 and 40 foot electrode spacing traverses show small anomalies, all
coincident with the main entry.  Again, for the latter traverses, it
would be difficult to pick out the anomalies if we did not know where
to look.   No anomalies were observed to be coincident vrith the fan
entry.
                               46

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               57230
               57220
               57210
               57200
               57190
               57180
               57170
                16000
                14000
                12000
                10000
                 8000.
                 6000
                 4000
                 2000
                16000
                14000
                12000
                10000
                8000
                6000
                4000
                2000
        OO I—
        	 LU
        CO U_l
    16000 --
    14000 --
    12000 --
    10000 --
     8000 --
     6000 --
     4000 --
     2000 --
                                15'  ELECTRODE SPACING
                          H	1	
                                 20'  ELECTRODE SPACING
                                                 25' ELECTRODE  SPACING
                                                 	1	
                                 LEFT ENTRY
                                     RIGHT ENTRY
  OVERBURDEN
-''MINE LEVEL
FIG.  15
                          I                I
          0               66              120               185
                          TRAVERSE  LINE (FEET)
ELECTRICAL RESISTIVITY  AND MAGNETIC FIELD  DATA ACROSS THE NEW WATSON
COAL MINE DRIFT  ENTRIES  -- OVERBURDEN THICKNESS -  15 FEET       AP11429
                                             47

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                   16000


                   14000

                   12000

                   10000

                    8000



                   16000

                   14000

                   12000

                   10000

                    8000
                   16000  --

                   14000  --

                   12000  --

                   10000  --

                    8000  --
                         0
15'  ELECTRODE  SPACING
20'  ELECTRODE SPACING
25'  ELECTRODE SPACING
                                        RIGHT  ENTRY
                             OVERBURDEN
                             MINE LEVEL
75
150
                                    TRAVERSE  LINE (FEET)
FIG.  16    ELECTRICAL  RESISTIVITY  AND MAGNETIC FIELD DATA ACROSS  THE  OLD WATSON
           COAL MINE RIGHT DRIFT ENTRY --  OVERBURDEN THICKNESS    15  FEET    AP11430
                                          48

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     12000
     11000
     10000
      9000
      BOOO
      7000
      6000
      5000
      4000
     12000--
     11000--
     10000--
      9000--
      8000--
      7000--
      6000--
      5000--
      4000--
                                                                      12000.
                                                                      11000
                                                                      10000
                                                                       9000
                                                                       8000
                                                                       7000
                                                                       6000
                                                                       5000.
                                                                       4000
         12000
         11000
         10000
          9000
          8000
          7000
          6000
          5000
          4000
         12000--
         I1000--
         10000 --
          9000--
          BOOO--
          7000--
          6000--
          5000--
          4000 - -
OVERBURDEN   -»•
MINE LEVEL   -
                             150            225
                           TRAVERSE LINE (FEET)
                                     30'  ELECTRODE SPACING
                                  H	1	
   35'  ELECTRODE SPACING
H	1	
   40'  ELECTRODE SPACING   -
  	1	
                                                                                          MAIN ENTRY
                                                                                                         FAN ENTRY
                                 150           225
                                 TRAVERSE LINE (FEET)
                        340
FIG. 17    ELECTRICAL RESISTIVITY AND  MAGNETIC  FIELD DATA  ACROSS  THE BIG SPRING #1 COAL  MINE DRIFT ENTRY
           AND FAN  ENTRY --  OVERBURDEN  THICKNESS    20 FEET  AT MAIN ENTRY AND 35  FEET AT  FAN ENTRY
                                                                                                                                    BP11312

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Although the magnitudes of the anomalies associated with the main
entry are not great, they do represent a successful deomonstration
under simple conditions.

The following conclusions can be stated about mine entry detection:

     Electrical resistivity apparently permits detection and location
     of the mine, entries in cases of shallow overburden.

     Highly mineralized water apparently does not have to be flowing
     through the entries for it to be detected by this technique.

     A fairly wide range of electrode spacings may be possible in
     the search for mine entries.  (See the results for the Mills
     #4 mine.)

Self-Potential

Mills #4 Coal Mine

The self-potential technique was extensively used on the Mills #4
coal mine area with total coverage obtained on a coarse grid.  Tight
coverage (10-foot electrode spacings) were obtained along all of the
electrical resistivity traverse lines.

The self-potential data collected over the Mills #4 site did not show
any correlation with the mine workings or the associated faults.

Computer generated contour maps of the earth potential over the mine
were produced.  Figure 18 is one such plot.  This particular map
shows a slight correlation with the mine workings.  The low potential
values appear associated with no mine workings (the eastern and
southern sectors are notable exceptions).  Regrettably, this sample
proved to be the only one which showed even this much of a correla-
tion.  No other computer generated contour maps nor any of the
potential plots from the traverse lines showed any definite correla-
tion with either the mine workings or the local faults.

Bitumen //I Coal Mine

The self-potential traverses across the shallow Bitumen #1 mine did
meet some success over the slump zones.  Figures 13 and 14 illustrate
self-potential minima over or adjacent to the slump zones that were
traversed.   The field crew observed the correlation in situ.  The
location of the slumps relative to the geophysical data is exact.  The
locations were established simultaneous to the surveys.
                               50

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CONTOUR INTERVAL   2 MILLIVOLTS
              100'         200

         SCHE IN FEET
          .
        FIG.  18   COMPUTER PLOT OF THE EARTH POTENTIAL  AROUND  SURVEY STATION  #2,  MILLS #4 COAL MINE,
                 (positive values only)
                                             	CP10395

                                                  -51-

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Bitumen #2 Coal Mine

Self-potential data collected along grid lines 1 through 10 over
Bitumen #2 was operated-on by the STAMPEDE program and plotted various
ways.  Different contour intervals were used and certain apparently
incompatible data points were discarded in producing certain of these
contour plots.  Figure 19 illustrates one of these plots relative
to the underlying mined area.  No obvious correlation between this
map and the mine workings is apparent.  This lack of correlation
persisted for the other plots.

The self-potential data is characterized by high amplitude (approxi-
mately 10-25 millivolts) noise.  This is true for all of the sites
studied, including Mills #4 and Bitumen #1 and #2.  The amplitude of
the anomaly expected from a coal mine drift is thought to be on the
order of 5 to 10 millivolts.  Hence, the noise in our data is of a
dominant nature.  As the result of this problem, no correlations
have been observed in any of the data.

New Watson, Old Watson, Knowles, and Big Spring #1
                       I
The self-potential plots revealed no observable correlations.

The 1971 data, as was the case in 1970, was characterized by high
noise levels.  This method, although unsuccessful in 1970, was held
over for testing during the spring 1971 wet hydrologic cycle.  High
soil moisture and ground water conditions were hoped to improve the
performance of this technique.  However, no apparent difference in
the data was observed.  This technique is considered to be not appli-
cable to the objectives of this program.

Induced Polarization

Mills #4 Coal Mine

Induced polarization traverses were run along three of the traverse
lines used previously for other survey techniques.  Traverse line #4
(Figure 20) is the furthest from the mine entries and was used to
serve as a control survey since there are no mine workings under it.
Line #6 (Figure 21) is a long line over the mine workings and Line #5
(Figure 22) runs over the two mine entries.

The survey along line #4, the control line, (100' electrode spacing)
illustrates a pronounced effect at the zero station considered to
have been caused by a topographic effect (the hillside drops off
steeply at this point).  A deeper seated anomaly, centered below
+3000 feet on the traverse, occurs at about n = 4 and deeper (Note:
n = dipole spacing, these values cannot be directly related to speci-
fic depths); hence, the perturbing effect should be deeper than the
                               52

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PA.  STATE FOREST t VWERS   ""
          N82       "
                                                                   ?   'A     {CONTOUR INTERVAL = 10 MILLIVOLTS)
                                                               0'               100'              200'             300'

            FIG. 19   SELF-POTENTIAL COMPUTER GENERATED CONTOUR MAP OVER A PORTION OF THE BITUMEN #2 COAL MINE, DATA CORRECTED TO BASE POINT (ZERO) ON LINE #1

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             -200'
                L_
 -100'     0
 -I	l_
100'    200'    300'     400
 I  	1	«       i
                               500
600'
                                                               700
800'     900     1000'
 I        1      --'
         n = 1  i


             2  -


             3


             4  -


             5  -


             6  -
                                  3.6
                                       3.3
                                           3.0
Ul
                                    PERCENT  FREQUENCY EFFECT 3.0  TO 0.3 CPS (CONTOUR  INTERNAL 0.3)
                                                                                                                         SURFACE
             -200

                I
            'A'  SEAM
             OUTCROP
           ON HILLSIDE
-100
                        FIG. 20   MILLS #4  COAL MINE, SURVEY  LINE I4(CONTROL  LINE-NO MINING ACTIVITY),CROSS SECTION
                                  WITH INDUCED  POLARIZATION DATA  (FREQUENCY  DOMAIN)

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                            PERCENT FREQUENCY  EFFECT 3.0 TO 0.3 CPS  (CONTOUR  INTERVAL 0.3)

OVf
^^^^^^^^^^^^^^^^^^^^^^^^^^^IVl A^HA^^^I /\l i ~~^:^^^— ^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^1 M I i
i i
00 1600 1500
1400
1 1 1 I II 1 1 III 1
1300 1200 1100 10DO- 900'- - 800 700 600 500 400 300
1
1 1 1 1
200 100 0 -100'
      FAULT
     A
   SEAM
  OUTCROP
ON HILLSIDE
                                                                        FAULT
                                                                                      FAULT
                                                    MINED AREA
                                                                                                                   SURFACE
                                                                                                                 OVERBURDEN
                                                                                                                    65

                                                                                                                 MINE LEVEL
FIG-  21   MILLS #4 COAL  MINE,  SURVEY LINE #6,  CROSS SECTION WITH  INDUCED POLARIZATION  DATA (FREQUENCY  DOMAIN)
                                                                                                                   •AP11796

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                  70       105'    140'    175
                 —1	1	1	l_
                                                     210'
                                                      '
245'
 '
                                                                 280     315      350'     385'     420
                       1.2 1.4 1.6
    n =  1  -|
or
o


3      2-
Ll_

z

°      3-
I—
«r
cc

2      4-
LU
C/0



S
Q_


°      6 -
                                                           2.0
                                                            2.2
                                                               2.4
                                                                   2.6
                                                                      2.8
                                                                         3.0
                                                                  2.2
                                                          2.6
                           PERCENT  FREQUENCY EFFECT 3.0 TO 0.3 CPS (CONTOUR  INTERNAL 0.2)
                                                                                                             SURFACE
                                                                                                      OVERBURDEN
                                                                                                          30'
  0      35        70       105     140     175'      210'     245      280      315      350'    385'     420
                                                  LEFT
                                                  ENTRY
                                                                     RIGHT
                                                                     ENTRY
FIG.  22    MILLS #4  COAL MINE, SURVEY  LINE #5,  CROSS SECTION  WITH INDUCED POLARIZATION DATA  (FREQUENCY DOMAIN)

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the coal seam.  The profile along  line  #6  indicates an anomaly at
about +600 feet on the  traverse  line  that  is related to  the large
mined section.  The anomalous percent frequency effect data between
+900 and 1200 feet is thought due  to  the same topographic effect
mentioned above.

The IP profile along line  #5  (Figure  22) over the mine entrances is
most encouraging  (35* electrode  spacing).  Although the  survey appears
to have not been  extended  far enough  to cover the right  entry ade-
quately, a distinct anomaly appears over the left entry.

Knowles Mine

The IP survey at  the Knowles mine  illustrates (Figure 23) an anomaly
that is correlatable with  the mine tunnel.  The anomaly  is subtle at
small n's, but pronounced  at large n's.  The pronounced  anomaly at
large n's is expected to be derived from features beneath the mine.
This survey was taken with 30' electrode spacings.

Magnetics

Mills #4 Coal Mine

Magnetometer traverses  were run  along all  of the traverse lines pre-
viously occupied  by resistivity  and self-potential surveys.  Generally,
the plots of the  corrected earth's magnetic field did not show any
consistent correlation  with the  ifline workings or the rock faults.
Specific traverses did  shov? correlations,  however,  Figure 24 illustrates
the negative anomalies  whieh aifg goinei^e'iit with the drift entries.

Bitumen #1 Coal Mine

Magnetics data was corrected and plotted along each of the survey lines
(see Figures 13 and 14).   No correlation between any of  the mine
features and the  data was  observed..

Bitumen #2 Coal Mine

The magnetics data was  plotted and studied for each of the survey lines
at Bitumen #2.  Figure  25  shows  in small scale the results of the
traverses relative to the  mine workings.   Again, no consistent correla-
tion is observed.  Computer generated contour plots of the same data
did not yield any additional correlation.

New Watson, Old Watson, and Big  Spring  #1  Mines

Magnetic field measurements were made along all of the traverse lines
over the coal mine entries.  The magnetic  plot in Figure 15 illustrates
the variation of  the earth's magnetic field along the two entries at
                               57

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01
00
                                             PERCENT  FREQUENCY EFFECT  3.0  TO 0.3 CPS (CONTOUR  INTERNAL 0.2)
                                                                                                                         SURFACE
                          300'     270'    240     210'     180      150'     120'    90"      GO'      30      0'
                                                                        DRIFT MINE  ENTRY
               FIG. 23    KNOWLES MINE, MINE  ENTRY SURVEY  LINE,  CROSS SECTION  WITH INDUCED POLARIZATION DATA  (FREQUENCY DOMAIN)

                                                                                                                                   AP11797

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   57,180
   57, 170
   57,160
   57,150
    57,140
=-  57,130
    57,120
    57,110
                                                                                LEFT  ENTRY
                                                                                                  RIGHT ENTRY
    57,100 I    I   I   I    I   I   I
          0
          EAST
                          50
                                          100
                                                            150
                                                                                                            300
                                                                                                                            350
                    200               250
                          TRAVERSE LINE  (FEET)
FIG. 24    MAGNETIC  FIELD DATA ACROSS  THE MILLS  #4 COAL MINE ENTRIES
                                                                                                                                             400
                                                                                                                                                              450
SSESf

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  ^/  /;///.
^m&&
  ^^^rrfxx a (
pa ST^TE FORSST t *«TE»S
    ' SO'I*""
                   0     100     200    300


          FIG. 25 TOTAL MAGHETIC FIELD TRAVERSE PLOTS FOR SURVEY LINES 1 THROUGH 10. BITUMEN »2 COAL MINE

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the New Watson mine.  A very large, negative anomaly is coincident
with the left entry.  This result is most gratifying, but the con-
sistency of these correlations is lacking.  (Subsequent field
activities at this site noted a powerline close to this portion of
the traverse line.  The large anomaly may be related to this source.)
Notice that the data over the right entry do not show an anomaly.
The right entry has a tight, earthem seal.  If the seal extends
down the drift so that it's beneath the traverse line, then the
significance of this data may be greatly enhanced.

The plot of the magnetic field data along the traverse line at the
Old Watson mine entry is illustrated at the top of Figure 16.  There
is a sharp negative anomaly associated with the mine entry.  It
should be noted that there is a vertical scale exaggeration here
relative to that of Figure 15.  Although the anomaly appears sharp,
it does not possess the amplitude of the anomaly in Figure 15, nor
does it stand out from the noise as well.

Figure 17 illustrates the magnetics field data along the traverse
line over the Big Spring //I coal mine entry and fan.  There is no
correlation between the magnetic field data with the mine entry at
Big Spring #1.

The negative anomalies observed are of the direction expected.  That
is, the-magnetic susceptibility of the drift (air), assuming that
it's open would be approximately 1 x 10 5 cgs units, whereas, the
magnetic susceptibility-of the -shale and sandstone would be about
5 x 10~6 to 5 x 10 5 cgs units.  Since the susceptibility of the
drift  (air) would be 'less, the magnetic flux lines would diverge
from the drift (air) and crowd into the surrounding rock.  The net
result would be a lower magnetic field intensity over any drifts or
subsurface voids.

The ability to detect these voids is something else and is dependent
on equipment sensitivity, background noise and other factors.  Back-
ground noise appears to be a limiting factor in this application.

VLF Electromagnetic

Mills #4 Mine

The strongest radio signal for the VLF surveys at the Mills #4 mine
was received from station NAA, Cutler, Maine on a frequency of 17.8
kHz and a radiated power of 1000 kw.  Although the signal was strong
for these surveys and could be nulled almost completely, the data
obtained and plotted did not show any significant correlation with
the entries or subsurface workings.  The in-phase and the out-of-
phase signal values remained fairly constant for each survey and did
not change slope significantly or cross.
                               61

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Bitumen #1

The plotted data for the two VLF survey lines at the Bitumen #1
mine improved somewhat over the Mills #4 data.  However, there
appeared to be no consistant correlation with the subsurface work-
ings.

New Watson, Old Watson, and Knowles Mines

The data obtained on the two VLF surveys at the Watson mines were
very similar to those obtained at the Mills #4 mine.  The in-phase
and out-of-phase curves remained relatively constant.

The VLF survey at the Knowles mine improved somewhat again in that
the in-phase and out-of-phase lines were not constant and some slope
changes occured.  This slight variation from the norm was not suffi-
cient to indicate the location of the mine entry.

Seismic Refraction at the Bitumen #2 Mine

Seismic refraction investigations were confined to the Bitumen #2
coal mine.  Detection of the mine workings was the objective.  Three
seismic phenomena were used to gain this objective.  These phenomena
included:  anomalous delays in arrival times, anomalous attenuations
of the seismic waves and cavity resonance.  In that Godson and
Watkins (1968) had considerable success in observing cavity reso-
nance due to the radial oscillations of the underground voids trig-
gered by seismic waves, the greater part of our effort was directed
at attempting to observe this phenomena as a prelude to using it for
detection pruposes.  It should be noted that Godson and Watkin's
experimental work is based on Biot's (1952) theoretical relationship
between the dimensions of a cylindrical bore in an infinite solid
and the resonant frequency.  The agreement between the experimental
and theoretical being within a factor of three.  Biot's relation
being:


     D=
         1.55f

where

     D = diameter of the bore
    Vs = shear wave velocity
     f = resonant frequency
We were at a loss to identify resonance on the early records.   (Reso-
nance is identifiable as a time-independent wave train persisting for
as short as one second or as long as four seconds.)  An experiment
was designed to show whether resonance could be generated in the
                               62

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mine workings or not.  The experiment consisted of placing a dynamite
charge in one of the mains of the coal mine, detonating it and
observing the seismic activity with a string of surface geophones
overlying the main.

A copy of one of the records obtained from this experiment is shown
in Figure 26.  Readily apparent from this record is evidence of
some resonance (unshaded area) extending for about one and a half
seconds after the usual wave arrivals have concluded.  The resonance
is not strong nor is it persistent when one considers that the energy
source was internal to the mine.  The energy was provided by one-half
pound of 40 percent strength dynamite which was placed on the mine
bottom.  No stemming was used, thereby, providing air coupling of
the energy to the two walls and the roof of the main.

By way of explanation for the lack of adequate resonance, the follow-
ing is offered.  Biot's relationship is true for a homogeneous media.
The work that Godson and Watson reported was concerned with tunnels
or cavities in (1) lava flows and (2) limestone, both of which were
homogeneous.  In our case, we were working with a cavity which is
composed of three different materials.  The bottom of the cavity is
underclay, the sides are coal, and the roof is siltstone.  These
three materials possess different elastic properties, hence, it may
be impractical to assume that radial oscillations from such a com-
posite would follow Biot's relationship, if indeed they exist at all.

Another approach to the problem of resonance inducement and detec-
tion would be. to define the frequency, amplitude and type of wave
required to induce resonance.  Once these factors are reasonably
well defined, an optimum detection system could be built.

The frequency required to induce resonance would, of course, be the
frequency of the resonance.  The frequency of resonance will have
to be more closely known than that provided by Biot's relationship.
Experimental determinations where possible would more closely define
the frequency and provide a catalogue of possibilities which could
be used for cases in which experimental determination is -impractical
prior to the actual field measurements.

The amplitudes of resonance inducing waves may not be important yet
attenuation losses due to the weathered zone, as well as the rock
strata overburden plus the sensitivity of the receiver system, will
dictate the amplitude threshold required.

The wave type required to induce resonance is unknown at this time.
Godson and Watkins noted that better resonance was obtained from
dynamite charges exploded at shallow-depth (approximately three feet)
                                63

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     SYSTEM   CENTURY GEOPHYSICAL CORP
             •ODEL 506
     SEISES.   10  FOOT SPICING
      GAIN   101
       FILTER!  NONE
      AUTOIATIC
   SAIN CONTROL.  NO
        CHARGE:  ';*  40t STRENGTH DYNAMITE
DEPTH TO CHARGE  25' (FLOOR OF  'B' MAIN)
    SYSTEI   CENTURT GEOPHYSICAL CORP .
             •ODEL 506
    SEISES:   10  FOOT SPACING
             30  FEET SHOT HOLE TO FIRST GEOPNONE
      GAIN:   UK
       FILTERS:  HOME
     AUTOIATIC
   GAIN CONTROL:  NO
        CHARGE:  »»  401 STRENGTH O
DEPTH TO CHARGE  3
                                                                                                                         ::  ^^  ^.':>.•.  •  J'1 <  '%V*  v• J^?,  • ^wtf-vv**  iff;;C^p
                                                                                                                           '•••"'"'• :'   "       *   ••  -*   '-•-'--'            - : :
HOTES:

TOP RECORD ILLUSTRATES POSSIBLE CAVITY RESONANCE
(UNSHADED PORTION)
BOTTIW  RECORD ILLUSTRATES A STRAIGHT LINE  SHOT
FROI THE SUE LOCATION FOR COIPARISON
CHANNELS 5 AND 1  ARE "DEAD"
THING  INTERVAL =  O.I SECONDS  BETIEEN IAJOR
                 DIVISIONS.
                                                           FIG. 26  PARTS OF TWO SEISMOGRAMS RECORDED OVER V MAIN,  BITUMEN #2 COM. MINE

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as opposed to larger charges exploded at deeper depths (or approxi-
mately 50 feet).  They suspect that since the shallower shots
generate larger Rayleigh waves (on the order of several order of
magnitude larger than normal compressional or shear waves), that
the Rayleigh waves may be the triggering mechanism for the resonance.
Although beyond the scope of this project, this possibility needs
to be proven and the implications for field procedure studied.

Radiometry at the Mills //4 Coal Mine

Airborne infrared scanner imagery obtained on 10 and 11 June 1970
and 14 April 1971 were studied for the following features:

     Local active water drainage
     Fracture traces and fracture trace intersections
     Faults
     Jointing and jointing patterns
     Slump zones

Vegetation cover prevented complete analysis for these features on
the June imagery.  However, in some cases, full vegetation assisted
in the analysis since there is a correlation between vegetation
health and vigor and some of the above features.  Figure 27 illus-
trates the result of an analysis of the April 1971 imagery in terms
of detection of local active water drainage.  The light tones repre-
sent exiting water from seeps and springs, pools of water and stream
courses.  Comparison of this imagery with that taken on 10 and 11
June 1970 readily indicates that the optimum time for infrared
imaging is at a time of year when the drainage is at or near a
maximum, when water temperature exceeds ground temperature, and
when there is no screening due to leaf cover.  This optimum time
is early spring.

It should be noted that while this technique allows great accuracy
in locating drainage sources, it cannot be used to distinguish
between acid and fresh water seeps except by association with visible
mine features.  A ground survey was made with a portable pH meter at
most of the seepage sources and in Trout Run.  This survey revealed
pH levels between 2.5 and 6.9.  All of the seeps and streams checked
drain into Trout Run, a tributary of Moshannon Creek.  There has
been considerable strip mining in the area and most of the drainage
is related to this activity.  The Mills #4 coal mine contribution
is almost negligible by comparison.

Soil Moisture Determinations at the Knowles Mine

The soil moisture profiles did not illustrate any correlatable varia-
tion with the location of the mine entry.  Although surface soil
moisture was being measured, it was hoped that due to the shallow
                                65

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                TOPOGRAPHIC  MAP
                                                             IR IMAGERY
APPROXIMATE FLIGHT TRACK
                           HOUTZOALE  QUADRANGLE
         FIG.  27   UTILITY OF AIRBORNE  INFRARED  IMAGERY  FOR DETECTION
                   OF ACID MINE  FRESH WATER SOURCES;  pH VALUES
                   OF WATER SOURCES  INDICATED;  14 APRIL 1971
                                                                            API 1825
                                       66

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depth to the mine entry  (approximately 20 feet) that a moisture
profile variation would be visible as a manifestation of the mine.
There is some precedent for this assumption in that soil moisture
varys significantly in soils overlying carbonate bedrock topography
(the deeper soils have the higher moisture content).  In the mine
case, however, the shale and sandstone strata comprising the over-
burden have quite different water permeability than the soils over
limestone; therefore, the phenomena is nonexistent.

Computer Data Reduction Methods

A computer program developed by the IBM Canada Laboratory in 1968
called Surface Techniques, Annotation and Mapping Programs for
Exploration, Development and Engineering (STAMPEDE) was selected
to aid in reducing the field data.  This program is adaptable to
application areas which require the quantitative description of
surfaces.  Programs are included for making numerical and analyti-
cal approximations to a set of three coordinate values defining a
surface, for manipulating one or more of these surfaces, and for
preparing a display of surface geometry in the form of printed or
annotated contour maps.  In addition, this program is capable of
determining volume, net volume, and area within the entire area
of interest or within a specific contour.

Once the program was received, it was made compatible with the
IBM 360-40 computer at HRB-Singer, Inc.  The program was verified
by comparing a computer plotted topographic map with that drawn
in the field from the same plane-table data.  After debugging,
the program was used to contour the field data as required.

The next few paragraphs discuss an in-house research effort directed
at the calibration, digitizing and computer processing of geophysi-
cal data.

We initially felt that existing equipments had the sensitivity and
accuracy required for the geophysical tasks to which they are
applied, i.e., detecting and locating abandoned coal mines.  We
felt that the principle limiting factor in accomplishing this task
was the ability to discriminate between the signal and the noise.
We felt that the application of signal enhancement and other analy-
tical techniques could overcome this limiting factor.

The first step that we took in this effort was to develop the ability
to quickly and efficiently convert the analog data, as recorded in
the field, to digital form for the purpose of computer software pro-
cessing.  Fortunately, the hardware required for this effort existed.
It required some interface engineering and the cooperation of several
groups within the company, including our Signal Processing and
Analysis Facility.
                               67

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A number of signal processing and enhancement possibilities are
incorporated into this overall capability.  The STAMPEDE program
package provides a basis for the addition of other analytical tools.
Some of the programs that are included or are planned are:  ampli-
tude analysis, amplitude moment analysis, Fourier analysis, auto-
correlation, residual determination, downward continuation and
model fitting.  Limited time and resources precluded the full bene-
fit of this in-house effort on this program.

Subsequent field experimentation with the various techniques led
us to re-evaluate the sensitivity and accuracy requirements of the
instruments for this task.  Our conclusion being that the current
state-of-the-art of conventional geophysical techniques are not
adequate to the task.  Although computer assisted analysis was
benificial and will continue to compliment this type of geophysi-
cal work, the basic problem of mine detection will have to be solved
first.  When this is achieved, the true utility of computer-aided
analysis can be demonstrated.

Geology

Philipsburg-Houtzdale Synclinal Basin
          !
The study of the general geology and the specific lithology of this
area included both field and literature investigations.  Table 3
(see page 19) illustrates the generalized stratigraphic section
for the mines in this region.  The following sections discuss the
regional geologic features, the Mills #4 mine area, fracture trace
analysis of the region, and other "A" seam coal mines.

The regional strike follows the axial trace of the Philipsburg-
Houtzdale syncline which runs diagonally (NE-SW) through the west
central, north central, and northeast sectors of the Houtzdale
quadrangle.  The strike varies from N59°E in the southwest to N40°E
in the northeast.

The regional dip varies from horizontal strata at the synclinal
axis to 4°-5°NW at the Mills #4 mine.  This gentle rise to the SE
carries the Lower Kittaning Coal (B seam) from an elevation of
approximately 1600 feet at Penn Five (Figure 1) to 1860 feet at the
Mills #4 mine.  The B seam is the main coal unit to be locally strip
mined although stripping operations were later carried out in
younger units (C,  D, and E seams).  The section overlying the B seam
is well exposed along stripping highwalls 1/2 mile NW and 1/2 mile
SW of the Mills #4 entries.  At these highwalls, 14 to 16 feet of
gray thin bedded fissile shale is observed to directly overlay the
coal.   The shale is followed by a thick sequence ( 25') of medium
bedded to massive cross-bedded sandstone.  A similar sequence was
                               68

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studied along a highwall 1/2 mile SW of Penn Five.  Near Perm Five,
an old mine entry into the B seam reveals the shale/coal contact.
The steep hillside immediately south of this old mine has been strip
mined.  The hillside exposes the complete post-Lower Kittanning,
Alleghency section and is capped by Conemaugh strata above 1800 feet
(elevation).

Mills #4 Coal Mine Area

The Clarion Coal  (A seam) was mined at Mills #4 and a sandstone
roof is present at the entry.  The A seam has also been strip mined
along the hillside northwest of the Mills #4 mine and a strati-
graphic section exposed in the highwall has provided exposure of
the post-Clarion and pre-Lower Kittanning section.

The eastern entry to the Mills #4 mine is at an elevation of approxi-
mately 1661 feet and sustains an intermittent flow of water.  The A
seam rises (SE) under the hillside containing the mine and outcrops
(covered) on the back slope overlooking the Osceola Reservoir at an
elevation of approximately 1800 feet.  The dip of the coal in the
mine approximates 4°31'NW.  Within the area of geophysical survey-
ing, the section is all pre-Lower Kittanning.  Surveys run east of
the base survey line carry onto Pottsville strata and, therefore,
onto strata below the mine level.  The overburden above the mine is
shallow.  The cover reaches a maximum of approximately 55 feet
between survey stations 1 and 3.

Fracture Trace Analysis

Jointing is prominant in the Allegheny rocks.  Measured joint direc-
tions in the sandstone sequence above the A seam correspond closely
to the joint directions reported by Nickelsen and Hough (1967) for
the Houtzdale Quadrangle (Figure 28).  They demonstrated that sys-
tematic joints (designated A) strike approximately perpendicular to
fold axes.  The fundamental joint system forms the basic unit of
jointing in the region.  It consists of systematic and nonsystema-
tic joint sets intersecting at approximately 90°.

Systematic jointing is of significance in an aerial study of fractures
since systematic joints cut completely through structural lithic units
and may cross the boundaries of successive rock units with some change
in orientation, surface character, and frequency.  Where mineraliza-
tion along systematic joint planes is lacking, leakage of meteoric
water into and out of mines occur.

Faulting is present in the Mills #4 area and is confined in strike
direction to the arc extending from N20°W to N85°W  (Figure 28).  The
fault known to border the mine on the SW has an observed strike that
corresponds to the systematic joint direction of N37°W.
                               69

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                                           NORTH
           (A)
                                                                (F)
                                                                                    (A')
                                                                                        EAST
                                                                               (A)
                                           SOUTH

                                         LEGEND
                               A   SYSTEMATIC JOINT  SET
                               A''-  NON-SYSTEMATIC JOINT  SET
                               F   FRACTURE TRACE
FIG.  28   GENERALIZED GEOLOGIC  STRUCTURAL TRENDS  FOR  THE HOUTZDALE  1\'  QUADRANGLE
                                                                                        AP10094
                                              70

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Fractures not corresponding to regional joint or fault directions
are grouped under the general term of fracture traces.  Fracture
traces are defined by Lattman (1958) as natural linear features
detectable on aerial photographs which are less than one mile long
and which are surface expressions of joints and small faults.
Fracture traces are considered to represent vertical fractures or
zones of vertical fractures because they are straight, regardless
of topography.

The dip of the strata is believed by Trainer and Ellison (1967) to
control the abundance of fracture traces because both vertical
joints and fracture traces appear to be more numerous in gently
dipping strata than those which dip more steeply.

Stero examination of 1969 photography (GS VBYX-12 U.S. Geological
Survey) of the Mills #4 coal mine are,a reveal fractures present in
the mine overburden.  A systematic joint set (A) runs across the
center of the mine approximately parallel to the'surveyed control
line.  Several fracture trace; intersections are noted over the mine.
The fracture traces may be grouped into two sets approximating
strike directions of N35°E and N85°W.

Other "A" Seam Coal Mines

This section includes the geology of the New Watson, Old Watson,
Big Spring #1, Knowles and Hoover coal mine areas.  All of these
mines are in the lowest mineable; coal unit of 'the Allegheny Group.
Koppe (1967) and Edmunds (1968) review the stratigraphy in the
Houtzdale Quadrangle and report on recent changes in stratigraphic
terminology of the Allegheny Group.  Within the Houtzdale quad-
rangle, the mineable coal belongs to the Clarion, Lower Kittan-
ning, Lower and Upper Freeport formations..  East of the Philipsburg-
Houtzdale synclinal axis (east of Moshannon Creek) the upper beds
of the Allegheny Group are absent and the majority of the "deep"
mines are in the lowermost or Clarion Coal.  The Clarion is a
single unit in this eastern area and is the equivalent of the
Brookville, A, A', and three-foot^ terminologies.  The Clarion
splits into 3 units — the Clarion 1, 2 and 3 coals northwest of
this area.  The single unit (A coal) varies from four to six feet
thick, is dirty, and generally carries a top bony bench.  Roof
rock is variable throughout the area.  A sandstone roof is present
at the Big Spring and Watson mines, whereas, a shaly-siltstone
roof rock is present at the Knowles and Hoover coal mines.

Clearfield Synclinal Basin - The Bitumen Coal Mines

The Bitumen coal mines are located in the west central portion of
the Renovo West, Pennsylvania 7 1/2' quadrangle.  The mines lie
within.1/2 mile (SE) of the synclinal axis of the northeastward
                                71

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extension of the Clearfield Synclinal Basin.  The regional strike of
this synclinal axis is N53°E as reported in Nickelsen and Hough
(1967).  Because of the virtually horizontal attitude of the strata
at the mine site, dip and strike measurements were unobtainable in
the field..  Systematic joint measurements in the field (N33°W) are
consistent with those reported by the authors cited above (N34°W).

The Bitumen mines are in the Lower Kittanning coal ("B" seams) of
the Allegheny series.  The Lower Kittanning coal at the Bitumen
mines lies wholly within an area of transitional environment of
deposition between marine and continental sedimentation for the
roof beds (Williams and Keith, 1963).

A stratigraphic section compiled from field measurements was pre-
sented in Table 4 (see page 24).  The B seam is 5.5 feet thick at
this location and has a black siltstone roof that evidently has
held up well at Bitumen #2.  This mine is clear in most drifts and
relatively dry.  The mine map apparently is accurate.  Entrance to
the mine is effected through a crawlway at portal 'C'.

The shallow overburden at portions of Bitumen #1 has collapsed into
the mine.  Slump zones are apparent on the surface and were mapped
during the plane-table survey.  No access to the mine was possible
as the entries are well covered (although not water sealed).  A
lithologic facies change apparently took place between the mines
as the roof rock at the eastern portion of Bitumen #1 consists of
fissile shale rather than sandstone.  This change in roof rock and
its weaker supporting strength is responsible for the large number
of collapse zones over Bitumen #1.

Fracture Trace Analysis - Bitumen Coal Mines

Airborne infrared imagery and aerial photographs were studied for
fracture traces and joint sets.  The aerial photos used were U. S.
Geological Survey, 9 inch, GS-VTH, dated 2 March 1944.  The general
area of the Bitumen #1 and #2 coal mines was emphasized in this
study.

Sterographic analysis of the aerial photographs and study of the
infrared imagery revealed three different strike directions of
existing fractures (see Figure 29).   The three directions corres-
pond to the systematic joint sets (A, A' and I) mapped by Nickel-
sen and Hough (1967).   The (A) direction corresponds to systematic
jointing in the shale and sandstone while the (I) direction refers
to systematic jointing in the coal.   Direction (A') approximates
the non-systematic joint direction expected in the shale and sand-
stones.
                               72

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                                             NORTH
     WEST
                   (A)
                                                                    (A')
                                             SOUTH
                    LEGEND

(A)   SYSTEMATIC  SHALE JOINT   MEASURED IN  FIELD

(I)   SYSTEMATIC  COAL JOINT   (NICKELSEN &  HOUGH  1967)

(A')  PROBABLE  NONSYSTEMATIC JOINT
                   FIG. 29   LINEAR  GEOLOGIC TRENDS  FOR THE BITUMEN  MINES AREA
                                                                                     AP1101B
                                               73

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Rather intense study was required to detect the subtle expression
of the fracture traces in the Bitumen mines area.  This was not
surprising since the absence of unique fracture trace directions
is to be expected in horizontal strata where fracture traces repre-
sent zones of joint and small fault concentration that are parallel
to the major joint sets.

Bitumen #1 is actually transected by two fracture traces in the (A)
direction, two fracture traces in .the (A') direction and is bounded
along the northwest portion of the mine workings by a fracture
trace in the (I) direction.  The relatively large number of fracture
traces associated with this mine may account, at least in part, for
the acid water drainage emanating from the mine. .The.gently sloping
terrain over the mine contributes in this regard, as rain run-off is
generally inhibited.  Rain water infiltrates to the mine workings
much more readily through the fracture trace zones, as they are
zones of high permeability.  Topographic lows are associated with
the fracture traces (usually the case) which when combined with the
gentle slope contributes significantly to the infiltration rate of
rain water into the mine.

Bitumen #2 is transected by one short fracture trace in the (A)
direction.  This mine is of relatively small extent and the over-
lying topography is relatively steeply sloping; hence, rain water is
well drained and does not infiltrate in the quantity necessary to
contribute to an acid water problem.
                                74

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                           SECTION VIII

                         FIELD VALIDATION
This phase was deleted in favor of applying the so designated effort
to Phase II, Field Measurements, and Phase III, Data Analysis and
Technique Evaluation.  Phase IV had been included in the project in
order to gain experience and costing data pertinent to the applied
usage of the successful techniques.  In that no technique or group
of techniques tested have been successful to the point at which
validation tests would be meaningful, it was in the best interest
of the project to continue with the field effort over well known
mine sites.
                                75

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                             SECTION  IX

                  PROBLEMS AND  CORRECTIVE ACTION


A number  of problem  areas were  encountered during the course of this
project.  The  following  sections summarize these problems and the
corrective actions taken to  overcome  the problems.

Accuracy  of the Mine Maps

The first problem, that  of the  accuracy of the mine maps, was of prime
concern.  All  of  the analyses performed are dependent on this factor.
Plotting  errors,  north arrow mislocated or incorrectly read from com-
pass, incomplete  maps and differential shrinkage of the map paper
could all contribute to  locational error and, hence, error in the
analyses.  Specifically, locational errors of points on the surface
of the ground  relative to the mine features as indicated on the mine
map will  be minimal  near a visually checkable feature, i.e., mine
entry.  Conversely,  the  error will be greater as the distance from
such features  increases.  In order to overcome this problem, emphasis
was given to the  collection  of  data near the main entries.

Data Collection During the Dry  and Wet Hydrological Cycles

Data collection during the "wet" hydrological cycle was never fully
achieved.  The 1970  field season was relatively dry and the expected
wet conditions in the spring and early summer of 1971 never material-
ized.  Theoretically, the electrical techniques should work better
during the wet cycle.  It is to the detriment of the project that
conditions were not  favorable for field experiment during this time.

Lack of Physical  Property Information

Although we have  a good  knowledge of the geology of the rock strata
in the vicinity of the various mines, exacting knowledge of the elec-
trical, magnetic  and other physical properties of the strata is not
available.  Information  of this type is desirable for an in-depth
analysis  of the geophysical  data.  It should be noted that although
this information  is  desirable,  it was not practical within the course
of this contract  to  pursue physical property determinations in that
at least  as great an effort  would be required as was allowed for this
entire project.

Nature and Conditions of Mine Workings

A great deal of speculation  on  the nature of the worked out mine
areas is necessary.  These areas may range from totally open, dry
workings  to completely collapsed water saturated rubble.  Additional
direct information on the workings is necessary in order to answer
                               77

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these questions that are so important to the data analysis.  Two
ways of obtaining answers to this problem exist.  The first approach
is to drill.  The drillers log may be studied for information on the
nature of the workings and also their locations relative to that
shown on the mine maps.  It was not possible to provide drilling
information during this project.  The second and more descriptive
approach is to explore the underground workings, provided access can
be had to the mine.  This was possible at the Bitumen #2 coal mine.

Loss of the Bitumen #2 Coal Mine Site

It came to our attention during the October-December 1970 quarter
that we may be faced with the loss of two of our coal mine sites prior
to the completion of our data collection activities.  Strip mining
was planned for the Bitumen #1 and #2 coal mine areas.  Efforts to
defer the stripping until our field activities were completed were
unsuccessful.   An airborne overflight of the Bitumen coal mines in
March 1971 revealed stripping well underway.  Bitumen #2 was com-
pletely stripped except for the fan and the "C" entry.  At Bitumen #1
approximately 210 feet of each original survey line was obliterated
due to a road cut.
                               78

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                               SECTION X

                            ACKNOWLEDGEMENTS
Thanks are extended to Mr. David Milward and Mr. Perry Gaddis for
their invaluable assistance in  the selection of abandoned coal mines
as field sites and in providing mine maps.  Both men were with the
Pennsylvania Department of Environmental Resources (Mr. Milward is
now retired).  Special thanks are extended to Dr. David Maneval and
Mr. John Buscavage of this same department for their help in the
execution of this project.

The Philipsburg Coal and Land Company is thanked for permission to
operate over the Mills #4 mine.  The Kettle Creek Mining Corporation
is thanked for permission to operate over the Bitumen mines.  Special
thanks is given Mr. William Lindberg for his assistance with the
Bitumen mines.  The Pennsylvania Department of Forest and Waters is
thanked for permission to operate in State Forest Lands over the
Bitumen #2 mine.

The Pennsylvania State University, Department of Geology and Geophysics,
is thanked for the loan of geophysical equipment.  Special thanks are
due Dr. Robert Alexander and Dr. Peter Lavin for their assistance in
this regard.

The Naval Ordnance Systems Command, Washington, D. C. is thanked for
permission to use a continuous  recording magnetometer developed under
naval contract at HRB-Singer, Inc.
The objective of this project was to demonstrate the feasibility of
geophysical methods in  the detection of underground mines, and mine
openings.  Such research projects, intended to assist in  the prevention
of pollution of water by industry, are required by Section 6b of the
Water Pollution Control Act, as amended.  This project of EPA was con-
ducted under the direction of the Pollution Control Analysis Section,
Ernst P- Hall, Chief, Ronald D. Hill, Chief, Mine Drainage Pollution
Control Activities, Donald J. O'Bryan, Project Manager, and Henry R.
Thacker, Project Officer.
                              79

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                           SECTION XI

                          BIBLIOGRAPHY
Ansari, A.M.A, Resistivity Investigations for the Location of Ground
     Water in the Barrens Area of Central Pennsylvania, M.S. Thesis,
     The Pennsylvania State University  (1959)

Antsyferov, M.S., Seismic-Acoustic Methods in Mining, Published from
     Russian by Consultants Bureau, New York, New York (1966)

Ault, W.V., "Isotopic Fractionation of Sulphur in Geochemical Processes,"
     Researches in Geochemistry, P.H. Abelson, ed., John Wiley & Sons,
     Inc., New York  (1959)

Barnes, H.L., "Surface and Subsurface Geochemical Prospecting for
     Metallic Mineral Deposits, Mineral Industries, 33, No.. 8 (1964)

Barnes, I. and Clarke, F. W., "Geochemistry of Ground Water in Mine
     Drainage Problems," U.S.G.S. prof, paper 473-A (1964)

Biot, M.S., "Propagation of Elastic Waves in a Cylindrical Bore Con-
     taining a Fluid," J. Appl. Phys., 23. 997-1005 (1952)

Blattacharya, P.K., and Patra, H.P., Direct Current Geoelectric
     Sounding.  Principles and Interpretation, D. Reidel Pub. Co.,
     Dordrocht, Holland, I48p. (1968)

Birman, J.H., "Geothermal Exploration for Ground Water," Geological
     Society of America  Bulletin. 80, No. 4, p. 617-630  (1969)

Briston, C., "A New Graphical Resistivity Technique for Detecting
     Air-Filled Cavities," Studies in Speleology, 1, Part 4, p. 204-
     227  (1966)

Buhle, M.B., "Earth Resistivity in Ground-Water Studies in Illinois,"
     AIME Trans., 34, No. 2, p. 395-399 (1953)

Cartwright, K. , "Temperature Prospecting for Shallow Glacial and
     Alluvial Acquifers in Illinois," Illinois State Geological
     Survey Circular 433  (1968)

Cartwright, K. , "Thermal Prospecting for Ground Water," Water Resources
     Research. 4. No. 2, p. 395-401  (1968)
                                81

-------
Caruccio, F. T., An Evaluation of Factors Influencing Acid Mine Drain-
     age Production from Various Strata of the Allegheny Group and
     the Ground Water Interactions in Selected Areas of Western
     Pennsylvania, Ph.D. Thesis, The Pennsylvania State University
     (1967)

Corbett, R. G., & Douglas, J.G., "Composition of Water Discharged
     from Bituminous Coal Mines in Northern West Virginia," Eco.
     Geol., 62, p. 848-851 (1967)

Davis, S. N., and DeWiest, J.M., Hydrogeology, John Wiley & Sons, New
     York, 463 p. (1966)

Degens, E.T., Williams, E.G., and Keith, M.L., "Environmental Studies
     of Carboniferous Sediments.  Part II:  Application of Geochemical
     Criteria," Bull. A.A.P.G., 42, No.  5, p. 981-997 (1958)

d'Invillers, E.V., "The Geology of Centre County," Second Pennsylvania
     Geological Survey, Report of Progress T4 (1884)

Dorbin, M.B., Introduction to Geophysical Prospecting, McGraw-Hill,
     Inc., New York (1960)

Dutcher, R.R., Jones, E.B., Lovell, H.L., Parizek, R., and Stefanko,
     R., "Mine Drainage, Part II:  The Hydrogeologic Setting,"
     Mineral Industries, 36,  No. 4 (1967)

Dutta, N.P., et.  al., "Detection of Solution Channels in Limestone by
     Electrical Resistivity Method," Geophysical Prospecting, 18,
     p. 405-414 (1970)

Earth Resistivity Manual, Soil Test, Inc., Evanston, Illinois, 52p.
     (1968)

Edmunds, W.E., Geology and Mineral Resources of the Northern Half of
     the Houtzdale 15-Min. Quad., Pa. Topog. & Geol. Survey; Fourth
     Series,.Atlas A 8 Sab (1968)

Ginzberg, I.I., Principles of Geochemical Prospecting, Pergamon Press,
     New York, New York, 311p. (1960)

Godson, R.H., and Watkins, J.S., "Seismic Resonance Investigation of
     a Near-Surface Cavity in Anchor Reservoir, Wyoming," Bull. Assoc.
     of Eng. Geol.,  IV, No. 1, p. 27-36  (1968)

Goldschmidt, V.M., Geochemistry, Clarendon Press, London  (1958)
                                82

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Gray, C. and Shepps, V.C., Geologic Map of Pennsylvania, Pa. Geol.
     Survey, 1:250,000  (1960)

Habberjam, G.M. , "The Location of Spherical Cavities Using a Tri-
     potential Resistivity Technique," Geophysics. 34, No. 5, p. 780-
     784 (1969)

Halliburton Company, New Mine Sealing Techniques for Water Pollution
     Abatement, FWPCA Publication No. 14010 DM0 163 p.  (1970)

Halliburton Company, Investigative Mine Survey of a Small Watershed,
     FWPCA Publication  No. 14010 DM0 90p.  (1970)

Harbaugh, J.W. and Carter, G.B., Computer Simulation in Geology,
     Wiley-Interscience, 575p. (1970)

Hawkes, H.E., "Geochemical Prospecting," Researches in Geochemistry,
     P.H. Abelson, ed., John Wiley & Sons, Inc., New York (1959)

Hawkes, H.E. and Webb,  J.S., Geochemistry in Mineral Exploration,
     Harper and Row, New York, New York, 4l5p. (1962)

Heiland, C.A., Geophysical Exploration, Hafner Publishing Company,
     New York (1963)

Heath, R.C. and Trainer, F.W., Introduction to Ground-Water Hydrology,
     John Wiley & Sons, Inc., New York, 284p. (1968)

Holland, C.T., Third Symposium on Coal Mine Drainage Research;
     Preprints, Bituminous Coal'' ^search, Inc., Monroeville, Pennsyl-
     vania, 406p. (1970)

Jakosky, J.J., Exploratio Geophysics, Second Edition, Trija Publish-
     ing Co., 1195p. (1960)

Jakosky, J.J., "Continuous Electric Profiling," Geophysics, 3,
     p. 130-153 (1938)

Johnson, A. I., "Selected Bibliography on Laboratory and Field Methods
     in Ground-Water Hydrology," U.S.G.S. Water Supply Paper 1779-A,
     21p. (1964)

Keller, G.V. and Frischknecht, F. C., Electrical Methods in Geophysical
     Prospecting, Pergamon Press, New York, 527p. (1967)
                                83

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Kelly,  S.F., "Geophysical Exploration for Water by Electrical
     Resistivity," Journal of New England Water Works Association,
     76_, No. 2 (1962)

Kennedy, J.M., "A Microwave Radiometric Study of Buried Karst Topo
     graphy," Geol. Soc. of Am. Bull., 79, p. 735-742 (1968)

Kennedy, J.M. and Edgerton, A.T., "Microwave Radiometric Sensing-  '
     of soil Moisture Content," Extract of Publication No. 78,
     General Assembly of BERN, Int. Assoc. of Scientific Hydrology,
     p. 418-429 (1967)

Koppe, E.F., Petrography of Coal in the Houtzdale Quadrangle, Clear-
     field County, Pennsylvania, Pa. Top. & Geol. Survey, Fourth
     Series, Bulletin M55  (1967)

Lahee, F.H., Field Geology, McGraw-Hill Book Company-, Inc., Fifth
     Ed.s 883p. (1952)

Lange, A.L., "Cave Detection by Magnetic Surveys," Cave Notes, 7,
     No. 6, p. 41-56  (1965)

Lattman, L.H., "Technique of Mapping Geologic Fracture Traces and
     Lineaments on Aerial Photography," Photogrammetric Engineering,
     2A_, No. 4, p. 568-576 (1958)

Lattman, L. H. and Nickelsen, R.P., "Photogeologic Fracture-Trace
     Mapping in Appalachian Plateau," Am. Assoc. Petroleum Geologist
     Bull., 42, p. 2238-2245  (1958)

Leighton, A., Clay and Shale Resources in Pennsylvania, Pennsylvania
     Top. & Geol. Survey Bulletin, M23 (1941)

Lidel, P.O., et. al., Comparison of Observed Resistivity Measurements
     to Construction Projects, South Dakota Department of Highways
     (1968)

McCracken, W.H., A Study of the Lower Pennsylvanian and Mississippian
     Systems in Rush Township, Centre County, Pennsylvania, M.S.
     Thesis, The Pennsylvania State University  (1947)

Mason, B., Principles of Geochemistry, John Wiley & Sons, Inc., New
     York (1960)

Merriam, D.F., Computer Applications in the Earth Sciences, Plenum
     Press, New York, 281p. (1969)
                                 84

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Mintzer, O.W., et. al.,  "Manual of Terrain  Investigation Techniques
     for Highway  Engineers," Transportation Engineering Center Report
     196-2, Ohio  State University, Columbus (1965)

Mintzer, O.W., and Struble, R. A., "Combined  Techniques for Terrain
     Investigation," Highway Research Record, No. 156, p. 33-61  (1967)

Money, H.M. and Wetzel,  W.W., Potential About a Point Electrode and
     Apparent Resistivity  Curves  for 2, 3 and 4 Layer Earth. Univer-
     sity of Minnesota Press, Minneapolis,  Minnesota  (1956)

Morley, L.W., "Mining  and  Ground-Water Geophysics/1967," Proceedings
     of the Canadian Centennial Conference  on Mining  and Ground-
     Water Geophysics  Held at Niagara Falls,  Canada,  in October 1967,
     Dept. of Energy, Mines, and  Resources, Ottawa, Canada, Economic
     Geology Report No.  26, 772p.  (1970)

Morrison, G.H., Trace  Analysis:   Physical Methods, Intel-science Pub-
     lishers, John Wiley & Sons,  Inc., New  York 582p. (1965)

Morrisson, F., et. al.,  "Magnetometer Evidence of a Structure Within
     the La Venta Pyramid," Sci.,  167, p. 1438-1490 (1970)

Nickelsen, R.P. and Hough, V.N.D., "Jointing  in the Appalachian
     Plateau of Pennsylvania," G.S.A. Bull.,  78, No.  5, p. 609-630
      (1967)

Nickelsen, R.P. and Williams, E.G., Structure and Stratigraphy of
     Pennsylvania Sediments of the Plateau  Area Near;_ Pnilip_sburg
     and Clearfield, Pennsylvania, Guidebook, 21st Annual Field
     Conf. Pa. Geologists, Alp. (1955)

Oberste-Lehn, "Remote  Sensors for Detecting Underground Cavities,"
     Rand Corp. ARPA Contract SD-79, DDC No,  AD 372 709  (1966)
     Confidential

The Ohio State University  Research Foundation, Acid Mine Drainage
     Formation and Abatement.FWPCA Publication No. 14010 FPR,
     82p.  (1971)

The Ohio State University  Research Foundation, Pilot  Study of Acid
     Mine Drainage, FWPCA  Publication No. 14010 EXA,  84p..  (1971).

Owen, T.E. and Suhler, S.A., Development of a Ruggedized Experi-
     mental Seismic Tunnel Detector, Interim  Technical Report Con-
     tract No. DAAK02-68-C-0033,  Southwest  Research  Institute,
     San Antonio, Texas, 121p.  (1968)
                                 85

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Paai, G., "Ore Prospecting Based on VLF-Radio Signals," Geoexplora-,
     tion, 3, p. 139-147  (1965)

Pakiser, L.C., Mahey, D.R., and Warrick, R.E., "Mapping Shallow Hori-
     zons with Reflection  Seismograph," A.A.P.G. Bulletin, 38, No. 11,
     p. 2382-2394  (1954)

Palmer, L.S., "Location of Subterranean Cavities by Geoelectrical
     Methods," Mining Magazine, 91, No. 3, p. 137-141 (1954)

Palmer, L.B.S "Examples of Geoelectric Surveys," The Institute of
     Electrical Engineering, Paper No-2791M, p.  231-243 (1958)

Reese, J.F. and Sisler, J.D., Bituminous Coal Fields of Pennsylvania,
     Introductory Volume, Part 3, Coal Resources, Pennsylvania Geol.
     Survey, Fourth Series, Bulletin M6, Part 3  (1928)

Rozelle, R'.B., Studies on the Kinetics of Iron (II) Oxidation in
     Mine Drainage, Wilkes College Research and  Graduate Center,
     Final Report to FWCPA (1968)

Scott, J.H. and Carroll, R.D., Surface and Underground Geophysical
     Studies at Straight Creek Tunnel Site, Colorado, U.S. Bureau of
     Reclamation Publications (1968)

Singer, P.C. and Stumm, W., "Acidic Mine Drainage:   The Rate Deter-
     mining Step," Sci., 167, p. 1121-1123 (1970)

Sisler, J.D., Coal Beds in Centre County, Pennsylvania,  Pennsylvania
     Topographic and Geologic Survey, Second Series, Bulletin No. 50
     (1922)

Smith, F.G., Physical Geochemistry, Addison-Wesley Publishing Company
     Inc., London (1963)

Stingelln, R.W.,  "Operational Airborne Thermal Imaging Surveys,"
     Geophysics,  XXXIV, No. 5, p. 769-771 (1969)

Sypher, P., A Discrimination Study of Seismic Tunnel Echoes, Final
     Report 7546,  Intrusion Detection and Sensor Laboratory, Research
     Division, U.S. Army Mobility Equip. Res. &  Devel. Command, Fort
     Belvoir, Virginia, 108p.  (1968)

Thatcher,  L.L.,  "Evaluation of Hydrologic Tracers," U.S.G.S. Prof.
     Paper 424-D,  p.  D-396 (1961)
                                86

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Trainer', F.W. and Ellison, R.L.,  "Fracture Traves in the Shenandoah
     Valley, Virginia," Photogrammetric Engineering. 33, No. 2,
     p. 190-199  (1967)

Van Lopik, J.R., "A Remote Sensing  Survey of Areas in Central
     Coastal Louisiana, Part  I,"  Texas Instruments, Inc., Science
     Services Division, Project NR-387-039 (1966)

Van Nostrand, R.G. and Cook,  K.L.,  "Interpretation of Resistivity
     Data," U.S.G.S., Prof. Paper 499, 310p. (1966)

Vanyan, L.L., "Formation of an Electromagnetic Field and Its Use: for
     Solving Problems in Structural Geology," Joint Publications
     Research Service, Washington, D. C., 138 p. DDC Document JPRS
     44 637  U968)

Ward, F.M., Lakin, H.W. ? Canney,  F.L., et. al., "Analytical Methods
     Used in Gebchemical Exploration," U.S.G.S. Bulletin, 1152,
     p. 1-100 (1963)

Ward, S.H. and Rodgers, G.R., Mining Geophysics, I & II, Soc. Explor.
     Geophysicists (1967)

Watkins, J.S., Godson, R.H.,  and  Watson, !K., "Seismic Detection of
     Near-Surface Cavities,"  U.S. Geological Survey Professional
     Paper 599-A, p. 1-12  (1967)

Wedepohl, K.H.,  et. al., Handbook of Geochemistry, Springer-Verlag,
     New York, Vol. 1 & 2  (1969)

Weitz, J.L., The Mercer Fire  Clay in Clinton and Centre Counties,
     Pennsylvania, Ph.D. Thesis,  The Pennsylvania State University
     (1954)

Williams, E.G.,  Stratigraphy  of the Allegheny Series in the Clearfield
     Basin (2 volumes), Ph.D. Thesis, The Pennsylvania State University
     (1957)

Williams, E.G.,  "Aspects of the Paleogeography of the Coal Measures
     of Western  Pennsylvania," Mineral Industries, 28, No. 9 (1959)

Williams, E.G.,  "Marine and Fresh Water Fossiliferous Beds in the
     Pottsville  and Allegheny Groups of Western Pennsylvania,"
     Journal of  Paleo., 34, p. 908-922 (1960)

Williams, E.G.,  and Keith, M.L.,  "relationship Between Sulphur in
     Coal and the Occurrence  of Marine Roof Beds," Eco. Geol., 58,
     p. 720-729  (1963)
                                 87

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                            SECTION XII

                 APPENDIX  - DISCUSSION  OF METHODS


A brief discussion  of  the  geophysical methods that were field-tested
follows.   It should be noted that the mathematical basis for these
methods are well covered in the  classical texts by Jakosky  (1960)
and Heiland  (1963)  and the theoretical  Volume (II) of Mining Geo-
physics by the  Society of  Exploration Geophysicists  (1967) and are
not treated in  this report.

Resistivity is  probably one of the most powerful geophysical tools
for this problem.   It  is widely  used for shallow earth investigations.

Conventionally, electric currents of external origin are needed to
locate targets  having  anomalous  electrical properties.  When these
currents are applied to a  material, the amount of current that flows
is related to the resistivity of the material, and the distribution
of the current  is determined by  the relative resistivity of the
inhomogeneities of  the medium.

The basic  procedure is to  measure the potential gradient on the surface
associated with a known direct current  or low-frequency alternating
current which flows in the earth.  Irregularities in the conductivity
below the  surface affect the relation between the current and the
potential  drop  at the  surface.

While the  range of resistivities in rocks and rock material may extend
from 10~3  to 106 ohm-meters, most common rocks have no consistent
difference in resistivity.   Except for  certain rock materials such
as the metallic sulfide minerals, the resistivity of a rock depends
primarily  upon  the  electrolyte concentration of the liquid filling the
interstices of  the rock formation itself.  A mined-out area can be
expected to have a resistivity somewhat different from that of the
surrounding country rock.   It will be either higher or lower depending
upon whether or not the void has collapsed and upon the quantity of
acid mine  water present.

The following brief summary  is representative of pertinent work by
researchers that helped to  shed  light on the use of resistivity to
this project.

Dutta, et. al.  (1970), reported  detection of solution channels in lime-
stone.  They noted that the  anomalies were higher resistivities.  A
fault was  also detected at  depths of 141 and 76 feet and confirmed by
drilling.  It is significant to  note that the presence of other than a
thin shale section over portions of the limestone (due to local fault-
ing) precluded the detection of  cavities in the limestone.  Hence, the
three-layer case (soil, shale, limestone) became too complex for
                                 89

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detection purposes.  The Schlumberger electrode configuration and
the one current electrode far' configuration were used exclusively.

Self-potential methods are based on the measurement of potential
differences due to currents generated by electrochemical actions
such as salt-concentration gradients; filtering action of certain
materials, particularly clays; flow of fluids through porous rocks;
and chemical reactions between minerals and pore-filling fluids.
The degree to which such potentials are produced or modified by
mining operations is unknown.

Airborne Radiometry.  Airborne infrared imaging has been success-
fully applied to the detection and mapping of faults, fracture
traces and geologic formation boundaries, among other features.
These features possess contrasting infrared radiation character-
istics relative to their background.   The contrast is due to higher
soil moisture associated with faults  and fracture traces and to
emissivity and thermal inertia contrasts between geologic rock
types, respectively.

Detection and mapping of surface water drainage associated with
mines is easily accomplished as was reported.  However, the optimum
conditions for this task require that the overflights be made in
early spring.  This time frame assures:  (1) peak water flow,  (2)
no tree cover, and (3) maximum temperature contrast between water
and terrain.

The detection of infrared radiation variations at the surface that
are manifestations of underlying mine workings is a much more com-
plex task.  Making the task complex are•factors such as:  (1) in-
tensity of the radiant energy from the sun,  (2) absorption of the
solar energy by the terrestial cover,  (3) emissivity of the
terrestual cover, (4) subsurface thermal conductivity, and (5)
conductivity of the thermal energy to air.  Theoretically, the
"signal" from/due to mine workings would be buried in the noise
contributed to the above factors.

Magnetic Method.  For the purpose of  detecting mine voids, it is
necessary that the concentration of magnetic minerals in the rock
strata surrounding the void be high enough to produce a measurable
change in the total magnetic field as measured at the surface.  That
is, the magnetic susceptibility of the surrounding materials must be
high enough to produce a contrast in the geomagnetic field that is:
within the sensitivity of the magnetometer.   (The magnetic suscep-
tibility is the ratio of the intensity of magnetization of the
material to the magnetic field intensity which established the
magnetization.)  Sedimentary rocks may have a susceptibility as low
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as 1 x 10 6 cgs units and some coastal sands may be as high as 1 x 10™
cgs units.  The magnetic susceptibility of soil materials may vary
greatly.

Iron litter within the void as well as water pipes, power lines, etc.,
in close proximity to, the area of measurement, in many cases will pro-
duce anomalies much greater than the void.  However, the magnetic
effect of the iron will produce positive anomalies while the voids
will appear negative.

The fact that the void is an extended feature will aid in the dis-
crimination of non-mine anomalies.  Some of the local effects can
be greatly reduced oy using a, gradiometer.

Seismic.  Conventional seismic methods utilize pulses generated in
the earth by explosive or mechanical means, and the detection of the
seismic waves by an array of detectors distributed on the surface or
in drill holes.  From the character and the relative arrival times of
the detected pulses, one can generally obtain information on the
depths, slopes, and thickness of strata.  From seismic velocity
measurements, the type of rock in a given strata can sometimes be
identified.  Although these techniques are straightforward and
effective in areas of simple stratification with small dips, in areas
where the strata are severly folded, or extensively faulted, or where
fill occupies much of the region, the seismic waves are scattered in
such a complex way that the structure often cannot be resolved.

Several seismic methods have been considered for the detection of
underground cavities or voids.  If the area has good reflecting
horizons below the void, reflection "shooting" above the cavity may
show the strata below the cavity,  with a time and/or energy level
anomaly or "shadow zone" directly above the cavity.  The distance
to which a shadow zone will extend from an obstacle before being
eliminated by diffraction around the obstacle is the critical factor.

Refraction seismic methods over relatively short distances may be
useful for detecting low velocity zones near the surface.  If either
the explosive or the geophone is located close to the void and the
other at the surface on the other side of the void, it is possible
that the effect of the void should be detectable.

Because of the sharp discontinuity in the graphic result when using
seismic refraction, this method is generally preferred over resis-
tivity for finding depth to bedrock.  For purposes of void detection,
the resulting velocity plot would consist of three velocity lines
(assuming the tunnel is in a homogeneous medium); an initial segment
representing the velocity of the surrounding material, a middle
segment with a different slope, and the third line segment having the
same slope as the initial segment.  In at least one instance where
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underground cavities were being located, this three-segmented line
was produced.  The object of the search was an underground tomb in
Italy and a refraction seismograph with a one-meter spread between
geophones was used.  The line of geophones was directly on top of
and on either side of the underground tomb.  The resulting seismic
profile had very sharp discontinuities, allowing the cavity to be
readily detected.  In some instances, the refraction seismograph
failed to detect underground cavities.  For example. Humble Oil
Company's refraction seismology team failed to detect Mannoth Cave
in Kentucky; several investigators failed to locate small lime-
stone caves.  Therefore, it appears that although the seismic re-
fraction method will, in some cases, detect underground tunnel-like
structures, it may not have a very high detection reliability.

Very Low Frequency (VLF) Electromagnetic.  Electromagnetic methods
utilize the measurement of secondary electromagnetic fields gene-
rated by induction in subsurface conductors.  For the VLF electro-
magnetic case, the primary energy sources are electromagnetic
fields generated by U. S. Navy VLF-transmitting stations.  That is,
the transmitted waves induce currents in subsurface conductors as
the waves pass through them.  The currents are formed in accord-
ance with the laws of electromagnetic induction.  The currents are
then sources of new waves which radiate from the conductors and
are detected at the surface.   Inhomogeneities in the electro-
magnetic field observed at the surface indicate variations in
conductivity of subsurface features.

Again, the mine itself may exhibit either limit of conductivity,
that is, highly conductive (rubble filled cavity full of highly
mineralized water) or insulative (noncollapsed void with no water).
Most likely, the mine will exhibit electrical characteristics inter-
mediate to these limits.  As is the case with resistivity, induced
polarization and self-potential, to be successful in this applica-
tion, the induction method relies upon a discontinuity in electrica.
characteristics between the mine and its surroundings and/or pre-
sence of an "indicator" such as a clay sublayer whose character-
istics are markedly different due to the presence of the mine/
absence of the coal.

Induced polarization techniques utilize a strong primary current
which polarizes the subsurface strata and produces a potential
field which persists after the current circuit is interrupted.  The
intensity of this potential field and its decay time are the para-
meters usually measured.  Field and laboratory experiments show
that buried metallic conductors such as sulfide ore bodies will
produce substantial induced polarization effects measurable on the
surface if the conductors are not too deeply buried.  Other experi-
ments have shown that ionic exchange in clays and similar phenomena
in water-saturated sediments will also produce sizable induced
polarization effects.
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The induced polarization methods can produce unique responses from
buried metallic conductors and water-saturated rocks.  They do not
inherently have any better depth penetration or resolution than
resistivity or electromagnetic methods.  The method may be most
valuable in detecting clays and other highly conductive layers
associated with the coal seam, rather than by direct detection of
underground cavities.  The best equipment used in the application
of the method is at least one order of magnitude more sensitive
than the equipment used in resistivity surveys.  This increased
sensitivity is useful because the techniques used minimize the re-
sponse of extraneous features.

Geochemical Methods.  In that geochemical methods were initially
proposed, it became apparent that they would not be used to any
large extent.  The following section discusses why.

The application of geochemical exploration techniques to the problem
was predicated on the basis of the detection and measurement of a
chemical "indicator" or "tracer".  The indicator has to be relatable
to the mining activity or the mining activity has to have caused the
indicator to change or cease to be detectable relative to normal   ,
concentrations (background).  The indicator generally is one that is
related to the mining activity and is mobile, detectable in low con-
centrations and non-reactive.  The obvious indicators are pH and
total iron.  In fact, these two indicators proved to be the best for
the task, in that (1) they are the physical components that make
mine drainage a pollutant, (2) the establishment of threshold norms
would be the same as that for pollution detection and (3) simple,
well-defined equipment and procedures have been established for
their analysis.

Once the site selection phase had been completed, it became apparent
that most of the mines visited were either non- or intermittent acid
water generators.  The mines that did produce acid water continuously
were easily traceable right to their entries by pH measurements.
Hence, the utility of the geochemical approach as an area or regional
reconnaissance tool was reiterated.

The applicability of this tool for detecting covered, hard-to-visually-
locate mines was questionable.  Study of the literature  [Ault (1959),
Barnes (1964), Baines, et. al. (1964), Caruccio (1967), Corbett &
Douglas (1967), Hawkes (1969), Holland (1970), Mason (1960), Morrison
(1965), Rozell (1968), Scott & Carroll (1970), Smith (1963), Thatcher
(1961), Ward', et. al. (1963), Wedepohl (1969)] yielded no clues toward
a soil indicator that would allow the mapping of a superimposed halo
which was relatable to mining activities or just entries  (if, indeed,
the entries were ever buried to the extent that this approach would be
required).   Similarily, stream sediment analysis and ground water
analysis, both of which appeared to be reasonable areas of inyestiga-
tion, proved to be unimportant for further consideration when the
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actual mine sites were studied.  This was due to the ease and utility
of simple pH measurements which provided the same basic information;
and the tracer analysis of water input sources lost its importance
when it was established, by observation of the mines, that primary
water sources are rain and snow melt due to percolation through the
overburden.  Hence, the geochemical approach was fundamentally
abandoned (except for pH studies related to airborne IR detection
of water sources) in favor of a greater emphasis on the geophysical
approach.
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1
<4 cress ion Number

5
2

Subject Field & Group
05
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
organization 	 	 •
                   HRB-Singer,  Inc., State College, Pennsylvania
                   Environmental Sciences Branch
     Title
                  DETECTION OF ABANDONED UNDERGROUND COAL MINES BY GEOPHYSICAL METHODS
  10
     Authors)
       Fisher,  Jr.,  Wilson
                                     16
                                        Project Designation

                                             EPA, WQO Project No.   14010EHN
                                     2] Note
 22
 23
     Descriptors (Starred First)
     *Mine Drainage,  *Coal Mines, ^Geophysics, Resistivity, Remote Sensing,
     Magnetic  Studies,  Seismology
 25
     Identifiers (Starred First)
     Self Potential,  Airborne Infrared Radiometry, Very Low Frequency Electromagnetic,
     Induced  Polarization
 27
     A bs tract
           Acid  drainage produced by abandoned coal mines continues  to  cause  serious  water
pollution problems.   Without knowing the exact location of  the  concealed  openings  and the
extent of the mine,  the application of known, at source abatement  techniques  is  virtually
impossible.  Drilling is the only known method for accurately determining the location
and extent of the mine voids, but this is extremely expensive.   This project  attacks  the
problem through  field studies of the following geophysical  methods:   electrical  resistivity,
self-potential,  infrared radiometry, total field and differential  magnetometry,  seismic
refraction and reflection, very low frequency electromagnetic and  induced polarization
over well documented, drift, coal mines.  Airborne infrared radiometry  proved to be an
excellent tool for detecting and mapping acid mine/fresh water  sources, acid  mine/fresh
water drainage,  and  fracture traces under selected conditions.   Resistivity and  magnetics
anomalies coincide with some (not all) drift mine entries.  Induced  polarization data shows
some apparent correlations with mine workings.  Other methods tested did  not  yield correla-
table information.  Conventional geophysical approaches to  this problem do not appear
adequate for the task.  Unconventional approaches including high frequency seismic, shear
wave  seismic, and induced polarization methods may provide  answers pending their further
development.
Abstractor
        Wilson Fisher.  Jr.
                              Institution
                                         HRB-Singer.  Inc.
 WR:I02 (REV. JULY 19691
 WRSI C
                                               SEND TO:  WATER RESOURCES SCIENTIFIC INFORMATION CENTER
                                                      U.S. DEPARTMENT OF THE INTERIOR
                                                      WASHINGTON, D. C. 20240
                                                            UU.S. GOVERNMENT PRINTING OFFICE: 197Z 484-484/153 1-3

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