USGS Circular 9368

Table 1.-Comparisons between USBM and USGS-KGS coal availability (minability) restrictions

	USBM	USGS-KGS
Land use restrictions:
Industrial constraints:
Powerlines	100 ft buffer	100 ft buffer.
Pipelines	100 ft buffer	100 ft buffer.
Oil and gas wells	200 ft square	200 ft square.
Highways and railroads	NA	NA.
Environmental constraints:
Cemeteries	100 ft buffer	100 ft buffer.
Major streams, lakes	100 ft buffer	100 ft buffer.
Towns and residences	300 ft buffer	300 ft buffer.
Ground slopes <65%	NA	NA.
Technical restrictions:
Minimum mining thickness:
Surface mining	12 in minimum	14 in minimum.
Deep mining	24 in minimum	28 in minimum.
Stability considerations:
Thicker coal beds too close	<40 ft above/ below	<40 ft above/ below
Deep mining too close	< 40 ft above/ below	<40 ft above/ below
Overburden too thin	<100 ft	NA.
Too deep:
Surface mines	>20:1 highwall ratio	>200 ft.
Deep mines	NA	>1,000 ft¹
Geologic factors	NA	NA.
Barrier restrictions:
Present mine barriers	50 ft buffer	50 ft buffer.
Future (planned) mine barriers	Actual area	NA.