Mine Mapping and Surveying - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 59

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 modern 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 1/2-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: I. 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 ) .