Air that has passed through an abandoned panel or area which is inaccessible or unsafe for inspection shall not be used to ventilate any working area in such mine. No air which has been used to ventilate any area from which the pillars have been removed shall be used to ventilate any working area in such mine, except that such air, if it does not contain 0.25% by volume or more of methane, may be used to ventilate enough advancing working areas immediately adjacent to the line of retreat to maintain an orderly sequence of pillar recovery on a set of entries.
4 Va. Admin. Code § 25-40-5340
Statutory Authority
§§ 45.1-161.3, 45.1-161.294 and 45.1-161.305 of the Code of Virginia.