4VAC25-101-170. Pillars of coal to be left unmined, and other protective measures.
A. When mining using an underground, auger or highwall mining method within 200 horizontal feet of a vertical ventilation hole or a gas well, the mine operator shall submit a plan showing the projected pillars of coal to be left unmined around each hole or well.
B. Pillars shall be situated so that each hole or well is centered within a pillar, and each pillar shall conform to the specifications shown in Table I below, based on the depth of cover above the area being mined. The entries developed adjacent to any pillar may not exceed 20 feet in width without prior approval from the chief. In no circumstances may the most narrow pillar dimension be less than twice the width of the adjacent entries.
| Table I | |||
| Cover (in feet) | Required Solid Pillar Area (in square feet) | Required Additional Pillar Area (Solid or Split, in sq. ft.) | Total Area Bearing Surface Required (in sq. ft.) |
| 0-149 | 3,600 |
| 3,600 |
| 150-249 | 5,625 |
| 5,625 |
| 250-349 | 10,000 |
| 10,000 |
| 350-449 | 10,000 | 5,600 | 15,600 |
| 450-549 | 10,000 | 13,000 | 23,000 |
| 550-649 | 10,000 | 22,000 | 32,000 |
| 650 or more | 10,000 | 30,000 | 40,000 |
Statutory Authority
§§ 45.1-161.3, 45.1-161.106, 45.1-161.121, 45.1-161.254 and 45.1-161.292 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 17, Issue 20, eff. July 18, 2001.