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4
Mine Mapping and Surveying
A key element of assessment of the potential for breakthrough of coal
slurry materials into underground mine workings is the accurate delineation
of the extent of those workings with respect to the ground surface in the
impoundment's basin area. This chapter deals with several aspects of that
problem. The adequacy of existing mine maps and recommendations for the
storage and preservation of maps make up the first part of the chapter. While
mine maps provide information critical to the characterization of a site, there
are significant limitations to some maps, particularly those for abandoned
mines and mines operating before 1969. In addition, standard practice in
mapping and surveying varies from site to site. When questions concerning
the accuracy of maps remain, additional effort to locate underground
workings is warranted. Chapter 5 reviews geophysical methods that can be
applied to locate underground mines.
SURFACE MAPS
There are two primary sources of surface topographic mapping are the
U.S. Geologic Survey's 7/-minute quadrangle maps and aerial topography.
The U.S. Geological Survey's contour intervals vary according to the
steepness of the terrain. A 40-foot contour interval is common for southern
Appalachia. The generally accepted accuracy in surface elevation using
these maps ranges from 20 to 40 feet. ~ contrast, mine maps are typically
maintained to a tenth or hundredth of a foot.
However, coa! companies commonly use aerial photography to
determine topography for critical construction projects such as refuse
impoundments, preparation plants, and mine portals. The contour intervals
for aerial topographic measurements usually vary in sensitivity relative to
the steepness of the local topography. It is common to have one or two foot
contours for relatively flat terrain and as much as 5 to 10 foot in mountainous
-
71
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72
COAL WASTEIMPOUNDMENTS
areas. Contours are generated from surveyed control points flagged at the
time of the flight. Maps so determined also show man-made features such as
roads, excavations, and buildings.
Where closed-loop underground mine maps are available (see below),
the accuracy in depicting the surface topography controls the accuracy by
which the coal outcrop is located on a hillside. The committee recommends
that adjacent to existing or proposed refuse impoundments, the coal
outcrop locations) be determined using aerial topographic measure-
ments.
UNDERGROUND MINE MAPPING
The use of inaccurate or incomplete mine surveys and maps may result
in construction of an impoundment in an area not known to have been
mined; if unknown mine workings are present, the impoundment could
suffer unexpected structural failure (Franklin et al.', 1997~. In areas where
impoundments are constructed near known or suspected underground mines,
vertical and horizontal barrier distances between the mined area and the
impoundment, as depicted on old maps or surveys, may not be accurate.
Regulations' promulgated as a result of the Federal Coal Mine Health and
Safety Act (30 C.F.R. § 75.1200-2 (b)), require closed-Ioop mine surveys.
However, surveys for many older mines' were not closed. Furthermore,
underground mine surveys may have been based on a foreman's notes or
sketches that lack a reference point or a recognized coordinate system and
therefore cannot be accurately located. These shortcomings are more
common in small mines or room-and-pillar mines where a number of short
panels were driven and extracted. Compounding the problem, some maps
and records of older mines have been lost or destroyed.
The condition and thickness of a barrier, whether composed of coal or
other rock type, between an underground coal mine and a surface
impoundment can be difficult to determine in the steep topography common
in Appalachia. Yet, this information is needed to quantify the potential for
breakthrough. The tools available to determine the extent of mining in an
abandoned mine and the condition and thickness of the outcrop are not
highly advanced. Although extensive drilling can be used; it may miss
smaller mined or disturbed areas. In contrast to invasive drilling,
geophysical techniques can obtain useful information without penetrating
the Earth's surface. The objective of geophysical surveys is to constrain the
physical characteristics of some three-dimensional volume of earth material,
including the presence of voids. Although no geophysical technique
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MINE MAPPING AND SUR KEYING
73
performs optimally under all geological and topographic conditions, multiple
geophysical techniques may be necessary to reduce the probability for error
to an acceptable level (see Chapter 5~.
The primary use of underground mine maps is to determine accurately
the dimensions of pillars and mine openings and to locate the mine with
respect to the surface and any horizontally or vertically adjacent surface or
other underground mines (Shackleford, 2001~. The following information
relevant to site characterization is included on a typical underground mine
map (30 C.F.R. §§ 75.1200, 1200-1~:
· All pillared, worked out, and abandoned areas, pillar locations,
sealed areas, future projections, adjacent mine workings within
1,000 feet, surface or auger mines, mined areas of the coalbed, and
the extent of pooled water;
Dates of mining, coal seam sections, and survey data and markers;
Surface features (e.g., railroad tracks, public roads), coal outcrop,
and 100-foot overburden contour-or other prescribed mining limit;
Mineral lease boundaries, surface property or mine boundary lines,
and identification of coal ownership.
A coal section, which describes the mined thickness of the sequence of
coal, rock, and partings, is listed on the mine map. Coal sections are
typically recorded when a survey sped is set (see definition in glossary). The
coal section permits calculation of mined coal tonnage, percentage of coal
recovery, and percentage of reject (in-seam and out-of-seam rock). An
example of a portion of a typical underground mine map is shown in Figure
4.1.
Underground and surface mine maps are collected and stored both on
the state level and by MSHA and OSM. Operators of underground mines are
required to submit maps to MSHA at least annually for the approval of
ventilation plans. These maps are maintained at the various MSHA district
offices or archived at a central location until the mine closes. Following
mine closure, a copy of the final map is forwarded to the OSM National
Mine Map Repository in Pittsburgh, Pennsylvania (see below). Therefore,
MSHA is a source of maps for active mines only.
There is considerable activity at the state level concerning mine maps.
For example, the Commonwealth of Virginia has embarked upon an
ambitious program to accumulate mine maps and place them in a digital
database (Sidebar 4.1~. Related activities underway in West Virginia and
Kentucky are discussed in Sidebars 4.2 and 4.3. Comparison of the mapping
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74
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MINE MAPPING AND SUR KEYING
75
SIDEBAR 4.1 Mine Maps and Storage, Commonwealth of Virginia
Virginia's mine map repository is coordinated through the Virginia
Department of Mines, Minerals, and Energy and relies upon the Division of
Mineral Resources and the Division of Mined Land Reclamation. It contains
4,226 digitized and geo-referenced mine maps, representing 70 to 80 percent of
the mined-out areas in the state. The remaining mines are not yet included
because the maps lack sufficient information for accurate location, because
mining occurred before Virginia required map records, or because Virginia has
not yet acquired the maps from coal companies.
The project began with 10,000 folded blueline mine maps and 30,000
microform or microfilm records. These maps ranged from the product of trained
surveyors, referenced to state plane coordinates or local coordinates, to hand-
drawn sketches lacking scale, a coordinate system, and reference points.
Eliminating duplicates and earlier versions of the same mine was the
department's initial task. Where possible, the Virginia Department of Mines,
Minerals, and Energy locates mines using a global positioning system. In an
effort to characterize errors in mine location, the department conducts random
checks using the global positioning system and coal company survey records.
The error for these maps is a function of the surveying accuracy, which in turn is
related to the age of the mine. The closure error of mines using modem
surveying techniques is 1:5,000 to 1:15,000. While older mines may not have
been surveyed or if surveyed, a closed loop may not have been used to quantify
error. Accuracy is predicated upon the methods used to locate the mine. The
Virginia Department of Mines, Minerals, and Energy estimates the following
degrees of accuracy:
· +500 feet for features (stream, creek, road, etc.) that locate mines;
· +80 feet for locations tied to U.S. Geological Survey topographic quad
rangle sheets and +150 feet for those tied to geologic quadrangle sheets;
· +10 feet for mines located by survey; and
· +250 feet (at best) for abandoned mineland portal locations.
In addition, a library was created to include digital U.S. Geological Survey
7/minute quadrangle maps, incorporating other data including gas wells,
pipelines, and abandoned mine-lands projects. A set of quadrangle maps is
available at nominal cost for all coal-producing counties in southwestern Virginia.
A significant attribute of the Virginia program is that the digital data are
accessible through industry-standard computer-aided design and geographic
information systems programs. Once the mapping program is completed and all
available mines have been entered in a geographic information systems
database, the search for missing mines will continue with a comparison with the
OSM database.
SOURCE: 1. Duncan, Virginia Department of Mines, Minerals, and Energy (VDMME),
personal communication 2001; and VDMME Division of Mineral Resources Maps
and Publications (http://www.mme.state.va.us/DMR/DOCS/MapPub/map_pub.html).
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76
COAL WASTEIMPOUNDMENTS
SIDEBAR 4.2 Mine Maps and Storage, State of West Virginia
West Virginia is in the process of creating a geographic information
system inventory of coal resources that incorporates both geologic informa-
tion and underground mine locations, at the standard 1:24,000 scale used for
U.S. Geological Survey topographic and geologic quadrangle maps. Coal
resource data include outcrop locations, structural contours of coal seams,
total (coal plus partings) seam thickness, and percentage of in-seam partings.
Stratigraphy and coal seam correlation are accomplished using core logs,
geophysical (e-logs), measured coal outcrop sections, in-mine coal sections
and bottom~f-seam elevations, coal bed discontinuities, and coal analyses
(heating value per pound [Btu/lb)] and percentage of sulfur, and ash).
The digital mine mapping system is in the initial stage of development.
Mapping has been completed for Fayette County and the northern panhandle
counties. The present focus of the project is the southern West Virginia
coalfield, where the majority of current mining activity occurs. Underground,
surface, and auger mines are being mapped. The West Virginia Geological
and Economic Survey is concurrently mapping the location of impoundments
that overlie old mine workings. Map records dating to the end of the 19th
century are maintained on microfiche at two state agencies. Records for more
than 100,000 mines are available for public inspection and copying.
SOURCE: N. Fedorko, West Virginia Geological Survey, personal communi-
cation, 2001.
approaches in Virginia, West Virginia, and Kentucky indicates significant
differences in scope of data collection, storage, and access.
National Archive for Mine Maps
OSM maintains a National Mine Map Repository in Pittsburgh,
Pennsylvania (http://mmr.osmre.gov). Some maps in the repository were
originally maintained in the U.S. Bureau of Mines files and were transferred
to OSM. OSM accepts maps for inclusion in the repository from various
sources, including the states, and makes the archived maps available upon
request. OSM has no regulation requiring the submission of maps but does
have informal arrangements with MSHA to provide copies of the final map
for abandoned mines. In addition, some copies of mine maps are prepared to
illustrate mine ventilation systems, and these maps may not contain all the
mine map information required by 30 C.F.R. §§ 75.1200 and 75.1200-1. The
repository may receive such copies in lieu of the final map.
=
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MINE MAPPING AND SUR VEGA
77
SIDEBAR 4.3 Mine Maps and Storage, Commonwealth of Kentucky
Kentucky maintains paper copies of maps for approximately 150,000
mines at the Kentucky Department of Mines and Minerals. Mine locations and
perimeters are recorded on U.S. Geological Survey topographic quadrangles.
Hard copies of the mines maps are stored at the Department of Mines and
Minerals and are available for public viewing. However, Kentucky coal
companies do not contribute any mine maps to the OSM National Mine Map
Repository (http://mmr.osmre.gov). Recently, Kentucky's auditor of public
accounts recommended that the Department of Surface Mining, Reclamation,
and Enforcement, the Division of Abandoned Mine Lands, and the Division of
Mines and Minerals locate, scan, and digitize underground mine maps for
Kentucky (Hatchett, 2001~.
Distribution of mine location information is limited by the Department of
Mines and Minerals. In accordance with state law, KRS 352.480, the mine
license-holder (typically the operating company), mineral owner, mineral
leaseholder, or mine operator must give written consent before a mine map
can be copied. Adjacent or nearby property owners may secure a copy of
mine maps by filing an affidavit alleging encroachment on property outside
the ownership or leasehold. The maps are copied by a private firm and may
take several days. The mine maps are not stored in digital format but are
generally available for mines dating from 1948 to the present.
SOURCE: Kentucky Mine Map Information Center (www.state.ky.us/agencies/
cppr/dmn/mmic.htrn).
The collection of maps in the OSM repository is either voluntary from
the states and other sources, or results from an informal arrangement with
MSHA. As a result, OSM and state records differ in many instances. The
committee concludes that the transfer of mine maps from MSHA to OSM
should, be better coordinated. The committee recommends that MSHA
work with OSM and state agencies to develop a coordinated and
assertive approach to collecting and archiving mine maps.
Records of the individual states should be compared with those of OSM
to ensure that both have the identical mine map database. As mine maps
from active operations are submitted to MSHA and state agencies, copies
should be forwarded to OSM, so the archival data can be updated. MSHA, in
coordination with OSM and the state agencies, should undertake a thorough
and comprehensive effort to acquire maps of abandoned mines, concurrently
with the updating of maps of active mines. This process should include
canvassing mining communities, land- and mineral-holding companies, and
former mine employees (engineers, geologists, landmen, surveyors,
superintendents, and foremen), historical societies and courthouses to
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78
COAL WASTEIMPOUNDMENTS
acquire or copy mine maps from coal companies. The Federal Abandoned
Mine Lands Fund could be a source of funding for this activity.
Storage Risks
Damage to archived mine maps can result from improper storage,
natural aging of the materials used, water, fire, or other circumstances
(Sidebar 4.4~. MSHA requires that underground mine maps be kept in an
area on the surface to minimize the danger of loss by fire or other hazards
(30 C.F.R. § 75.1200~. The committee concludes that electronic data storage
can reduce the risk of permanent loss or damage of mine map data and
improve the ability to maintain multiple backup files both on- and off-site.
The committee recommends that upon receipt of a paper copy of a mine
map, the state or federal agency should have it scanned into electronic
data files. The original paper maps should be stored in fire- and flood-proof
vaults, while electronic copies of mine maps should be stored on site with
regular backup to an off-site facility.
Mine Surveying
Accurate mine maps will be critical to future site assessment for coal
waste impoundments, as well as for other land-use decisions. An important
component of an accurate map is the closure of the mine survey. Closure is a
measure of the acceptable error within a closed-loop survey. Closure
standards for surface surveys vary widely by state (Table 4.1) and type of
real property (e.g., urban, suburban, or rural). MSHA regulations (30 C.F.R.
§ 75.1200-2) require operators of all underground mines to conduct a closed-
loop survey, but do not specify the standard of closure and the distance
between the last closed loop and the active face.
The committee concludes that the establishment of uniform mine
surveying and mapping standards is essential to ensure that underground
coal mines are accurately located" with respect to other mines and surface
structures, including refuse impoundments. Therefore, the committee
recommends that MSHA set standards for minimum closure error for
all underground closed-loop surveys and that a closed-loop survey be
maintained within a standard distance (to be determined by MSHA).
Mine elevations are also an important component of a mine survey. The
mine elevations are posted on the map adjacent to each sped. The sped is the
underground equivalent of an iron pin or steel rod that marks property comers
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MINE MAPPING AND SUR KEYING
79
SIDEBAR 4.4 Kentucky Fire Destroys Mine Maps
A fire on November 12, 1948, destroyed at least 30,000 mine maps at
the Kentucky State Department of Mines and l\/linerals. This facility was
housed in a University of Kentucky building, which also contained the Botany
Department and the Kentucky Geological Survey. The Mines and Minerals
Department lost, in addition to the maps, its reports, including safety records,
inspection reports and recommendations. Many of these maps charted
abandoned mines dating from 1884 to 1948. State geologic maps escaped
the fire because they were kept at the home of the state geologist. The cost
of damage was assessed at $200,000, but many of the lost records were
irreplaceable.
Mine maps are now stored at Kentucky's Mine Map Information Center.
This center has operated the Mine Map Repository for the Kentucky
Department of Dirges and I\ Morels for the past 28 years. The center currently
houses 100,000 coal mine maps and 140,000 mine records. Although a few
of the maps destroyed in the 1948 fire have been replaced, the majority of the
maps in the repository date only from 1948.
SOURCE: Courier-Journal (Louisville), 1948; Lexington Herald Leader, 1948.
in a surface survey. The horizontal (x,y) location of each sped is referenced
to the mine coordinate system. The z component is defined by the bottom-
of-seam elevation, a critical component of mine surveying. Current
surveying practice is to establish bottom-of-seam elevations by a level
survey (30 C.F.R. § 75.1200-l~k)~. However, older mines sometimes used
the top of the seam to refer to mine elevations. Hence, caution should be
used in evaluating elevations on older maps.
The primary use of elevation data is to track the flow path and potential
total pressure Ready of water that may accumulate in the mine. The data can
also be used for vertical location of the active mine in the framework of
overlying and underlying seams, which may be actively mined or may
contain abandoned mines, and for identification of undulations in the mine
floor that frequently correlate with poor roof or floor conditions.
The thickness of the outcrop barrier is critical to the evaluation of blow-
out, blow-in, or breakthrough potential (see Chapters 3 and 6~. Because the
last cut is typically left unbolted, the measurement must be made remotely
from the protective cover of supported mine roof. Remote measurement can
be routinely accomplished with laser or sonar equipment that indicates
distance by the reflection of light and sound waves, respectively. The mine
engineer or land surveyor should be responsible for the accuracy in
documenting the extent of the final cut. Under no circumstances should the
-
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80
TABLE 4.1 Required State Surveying Closure Standards
COAL WASTEIMP6UNDMEN~
State Mine Surveys
Property Surveys
AL
IL
IN
KY None/federal
MD
OH ** 1 :5,000
PA
TN None
VA Same as rural
WV
1 :10,000 for urban/commercial/high risk
1 :7,500 for suburban
1 :5,000 for rural
ALTA* standards.
None specified.
1:10,000 for urban/commercial/high risk
1 :5,000 for rural
1:15,000 for urban/commercial/high risk
1 :10,000 for suburban
1 :7,500 for rural
1 :5,000 for mountains and marshland
1 :5,000 for urban/commercial/high risk
None specified.
1:10,000 for urban/commercial high risk
1 :7,500 for suburban
1 :5,000 for rural
1 :20,000
1 :1 0,000
None specified.
* ALTA: American Land Title Association (1:15,000 urban, commercial/high
risk; 1:10,000 suburban; 1:7,50~rural; 1:5,00~mountains and marshland)
** Data for Ohio: Mark Jones, Ohio State Board of Registration for Professional
Engineers and Surveyors, personal communication, 2001.
SOURCE: C. Gillian and M. Wooldndge, Alliance Consulting, personal communi-
cation, 2001
mine foreman authorize the active section to be abandoned or pillars to be
recovered until Me final depth of each heading has been recorded. The
committee recommends that the mine foremen and surveyors be required
to record the depth of the last cut taken to a level of accuracy to be
determined by MSHA. It is imperative that any areas not completely
surveyed be noted as such.
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MINE MAPPING AND SUR KEYING
81
Coordinate Systems
At least two and preferably three reference points are established on the
surface, usually near the portal or shaft (30 C.F.R. § 75.1200-l~h)) before an
underground mine is opened. These surface points are tied to a coordinate
system (latitude and longitude, state plane, or local) (Sidebar 4.5), so as to
enable mine workings to be accurately located in the framework of
surrounding surface features. The surface points are a permanent reference
that can be used if the portal or shaft location has become obscured by
collapse or post-mining reclamation. Subsequent mine surveying and
mapping is based upon a fixed point within the mine, a point-of-beginning,
that is referenced to the surface points.
The majority of active underground mines use the state plane coordinate
system. The surface points are fixed surface monuments, tied to both the
state plane system and at least one point referenced to latitude and longitude.
Using state plane coordinates is advantageous because utilities (electric
power lines, gas transmission lines), roads (federal, state, and county), and
other planimetric features are typically referenced to the state plane system;
and because U.S. Geological Survey topographic maps list both North
American Datum 27 latitude and longitude and state plane coordinates, so
mines can be located easily on commonly available maps.
The committee concludes that the variety of mapping and coordinate
systems in use at present increases the potential for misinterpretation or
inaccuracy in underground mire locations. Therefore, the committee
recommends that state plane coordinates or latitude and longitude and
bottom-of-seam elevations as the map base reference. However, when
using latitude and longitude, the mine operator should clearly designate
whether the mapping is based upon North American Datum 27 or North
American Datum 83. Elevations of seam bottom, used to establish the
vertical position of the mine, must be referenced to mean sea level.
Unfortunately, no uniform standard sets an appropriate coordinate
system or the type and placement of surface reference points. The choice of
a mine coordinate system can vary with the age of the mine, the operating
company, the geographic location, or the mineral lessor. As expected, the
largest variation in practice occurs in older mines (pre-1969) and small
mines. Historically, local coordinate systems have been prevalent where a
single entity owned the mineral rights to large, contiguous tracts. Where this
practice continues, it is limited to specific properties controlled by mineral-
holding companies. In these instances, a coordinate transformation between
the local and state plane coordinates is given. Similarly, for small hilltop
mines operating in remote areas, there was little economic justification for
-
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82
COAL WASTEIMPOUNDMENTS
SIDEBAR 4.5 Coordinate Systems
The most commonly used coordinate system today is latitude and
longitude, which are defined by reference planes based on the Prime
Meridian and the Equator (Snyder, 1987~. Latitude is measured in degrees
north or south of the Equator, and longitude is measured in degrees east or
west of the Prime Meridian.
In the United States, the state plane system was developed to provide
local reference systems that were tied to a national datum. This system
divides the United States into more than 100 distinct grid zones and provides
an easily used, flat grid that maintains a difference between geodetic and grid
distance of 1:10,000 or better. The first state plane system was developed in
the 1930s and was based on the North American Datum 1927 (NAD27) (in
feet). This system has been largely superseded by the North American
Datum 1983 (NAD83) (in meters), although maps in NAD27 coordinates are
still in use.
Mine surveyors can also use a local system based on an on-site
monument. A grid is established based on direction and distance measured
from the monument. These coordinate systems, because they do not take
into account the curvature of the Earth, lose accuracy as the grid is extended
away from the base station. In addition, these systems may be difficult to
transform with other coordinate systems, especially if the on-site monument
is displaced or unmarked.
SOURCE: Dana, 1999.
the time and expense associated with a closed-loop survey to tie the mine to
a U.S. Geological Survey monument.
Where large mineral-holding companies control mineral rights,
considerable time and effort has often focused on establishing transfo~ma-
tion equations between local and state plane coordinates. The equation
involves a fixed rotation angle and lateral offset to convert from the local
system to state plane coordinates. However, in some instances a single,
unique coordinate transformation is not applicable to an entire property.
Thus, conversion of a particular mine map from local to state plane
coordinates, requires knowledge of the geographic limits of a particular
coordinate transformation. The committee recommends that appropriate
coordinate transformation equations be listed on the mine map.
Where no coordinate transformation exists, extreme care must be used
in referencing maps from abandoned mines into state plane coordinates or
latitude and longitude. In these situations, the transformation may be based
upon aligning creeks, roads, or other planimetric features to establish the
mine location. However, the surveyor or engineer must recognize that the
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MINE MAPPING AND SUR KEYING
83
location of these features may have been drawn freehand and not established
by an accurate survey. The main objective of surveying is to depict
accurately the underground mine workings; surface features are secondary.
Furthermore, without survey stakes or monuments, the natural meandering
of creeks over time and realignment of roads may invalidate a surface
survey. Me committee concludes that surveys based on data not tied to
stakes or monuments may not be accurate. The committee recommends
that a qualifying statement accompany any crate transformation
that is based upon the alignment of surface features.
Surface hanzontal and vertical contraIs should be referenced to
permanent survey monuments. The committee recommends that MSHA
establish standards to improve and maintain the location of surface
controls. Monuments should be referenced to state plane coordinates and at
least one monument located in Norm American Datum 27 or 83, or latitude
and longitude (Sidebar 4.5~. They should be anchored in rock and located so
that they are not obliterated or obscured by reclamation and other activities
associated with mine operation and closure. Monument locations should be
established by closed-loop survey (with minimum closure errors consistent
with underground surveying standards recommended above) from a fixed
monument for which the accuracy of location is equal to that of a U.S.
Geological Survey monument. The elevation of the surface monuments
should be referenced to mean sea level and equal in accuracy to that of a
U.S. Geological Survey monument.
Identification of Geology and Coal Seams
In some instances, companies require mine surveyors, foreman, and
engineers to record geological observations or conditions in the mine floor
or roof rock. However, this requirement is not universal. Roof falls, floor
heave, and water or gas inflow are examples of where geologic information
would commonly be noted on a mine map. As discussed in Chapters 3 and 6,
the potential for subsidence is critical to quantifying the risk for slurry to
enter the mine workings. Although geologic information is contained within
He permit, site-specific data are important when mining adjacent to the
outcrop. The committee concludes that the geologic information contained"
within the mine permit documents and within company exploration and well
records is usefulfor determining the presence and extent of potential ground
weaknesses that could affect waste impoundments. Therefore, the
committee recommends that MSHA work with the state regulatory
agencies to determine which mine permit documents should be retained,
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84
COAL WASTEIMPOUNDMENTS
in what form, and for how long. Such information might include the
presence of fractures, faults, joints, "hill-seams" (tension cracks), and water
inflow from the roof or floor.
The designation of a coal seam should be regarded as approximate,
subject to verification based upon: seam elevation, seam thickness, and
location of marker beds as obtained from core logs; elevations of seam
bottom obtained Tom the mine map; or comparison with the elevations of
overlying or underlying mines. Although several resources (e.g., Toothman,
1977; National Geologic Map Database's Geologic Names Lexicon at
http://ngmdb.usgs.gov/Geolex/geolex_home.html) exist for designating a
particular coal seam, the correct name is not always identified. For example,
a coal seam may be referred to by several different names depending on
geographic location, mine operator, absence of lateral geologic correlation,
or economic value. This point is clearly illustrated by a few examples: In
Pike County, Kentucky, the Pond Creek coal seam is also known as the
Lower Elkhorn seam, which in West Virginia is synonymous with the No. 2
Gas seam. In Lynch, Kentucky, the geologic cross section shown on the U.S.
Geological Survey 7/-minute geological quadrangle map describes the first
three above-drainage seams as the Harlan, Kellioka, and Darby. However,
on the same property they were referred to as the A, B. and C by one coal
company and the 180, 240, and 260 by a second company. Upon crossing
Black Mountain into Virginia, these seams are known as the Wilson, B
(Marker), and Taggart. The committee concludes that coal seam names are
potentially imprecise. Therefore, the committee recommends that coal
seam names not be the sole basis for determining the vertical location of
an abandoned mine.
SUMMARY
Accurate mine maps are critical to establishing the location of
underground mine workings with respect to existing or proposed coal refuse
impoundments. Mine maps are the primary means by which the thickness of
the outcrop barrier (horizontal separation) or overburden thickness (vertical
separation) are determined. The accuracy of mines operated since the 1970s,
in which surveys were made with modern equipment and closed loops, are
likely to be suitable for use in the design of an impoundment. Maps for older
mines may or may not be suitable. Furthermore, unrecorded final cuts may
compromise the accuracy. In such cases, additional investigation of the
locations of abandoned mine workings in warranted. The next chapter
describes geophysical methods for such investigations.
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MINE MAPPING AND SUR VEY~G
85
In many instances, nonexistent, erroneous, or incomplete mine maps
prevent knowing the extent, location, and depth of mined areas. Therefore,
the committee recommends that MSHA work with OSM and state
agencies to establish standards for mine surveying and mapping. These
should include the following:
.
· Determining surface coal outcrop locations by aerial topo-
graphic measurements, where adjacent to existing or proposed
refuse impoundments,
Implementing a coordinated and assertive approach to collecting
and archiving mine maps,
· Scanning paper copies of mine maps into electronic data files
upon receipt,
· Setting standards for minimum closure error for all underground
closed-loop surveys and that a closed-loop survey be maintained
within a standard distance (to be determined by MSHA),
· Recording the depth of the last cut taken to a level of accuracy
to be determined by MSHA,
· Using state plane coordinates or latitude and longitude, and
bottom-of-seam elevations as the map base reference,
Listing of appropriate coordinate transformation equations on
the mine map,
Adding a qualifying statement to accompany any coordinate
transformation that is based upon the alignment of surface
features,
Improving and maintaining the location of surface controls,
Determining which mine permit documents should be retained,
in what form, and for how long,
· Avoiding the use of coal seam names as the sole basis for
determining the vertical location of an abandoned mine.
-
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86
COAL WASTE IMPOUNDMENTS
Mineral lease boundaries, surface property or mine boundary
lines, and identification of coal ownership.
A coal section, which describes the mined thickness of the sequence
of coal, rock, and partings, is listed on the mine map. Coal sections are
typically recorded when a survey sped is set (see definition in glossary;
or Mining in Manitoba, 2001~. The coal section permits calculation of
mined coal tonnage, percentage of coal recover, and percentage of
reject (in-seam and out-of-seam rock). An example of a portion of a
typical underground mine map is shown in Figure 4. ~ .
Underground and surface mine maps are collected and stored both on
the state level and by MSHA and OSM. Operators of underground mines
are required to submit maps to MSHA at least annually for the approval
of ventilation plans. These maps are maintained at the various MSHA
district offices or archived at a central location until the mine closes.
Following mine closure, a copy of the final map is forwarded to the OSM
National Mine Map Repository in Pittsburgh, Pennsylvania (see below).
Therefore, MSHA is a source of maps for active mines only.
There is considerable activity at the state level concerning mine
maps. For example, the Commonwealth of Virginia has embarked upon
an ambitious program to accumulate mine maps and place them in a
digital database (Sidebar 4.1~. Related activities underway in West
Virginia and Kentucky are discussed in Sidebars 4.2 and 4.3.
Comparison of the mapping approaches in Virginia, West Virginia, and
Kentucky indicates significant differences in scope of data collection,
storage, and access.
National Archive for Mine Maps
OSM maintains a National Mine Map Repository in Pittsburgh,
Pennsylvania (http://mmr.osmre.gov). Some maps in the repository were
originally maintained in the U.S. Bureau of Mines files and were
transfe~ed to OSM. OSM accepts maps for inclusion in the repository
from various sources, including the states, and makes the archived maps
available upon request. OSM has no regulation requiring the submission
Prepublication Version - Subject to Further Editorial Correction
Representative terms from entire chapter:
mine map
