4VAC25-101-120: Survey requirements

A. All vertical ventilation holes shall be drilled with due diligence to maintain, within reason, a vertical hole bore.

B. The permittee shall use an inclination survey on any vertical ventilation hole that penetrates a minable coal seam. The inclination survey shall be conducted from the surface to the lowest minable coal seam penetrated by the hole as follows:

1. The first survey point shall be taken at a depth not greater than the most shallow minable coal seam.

2. Thereafter, shot points shall be taken at each minable coal seam or at intervals of 200 feet, whichever distance is less, to the lowest minable coal seam penetrated by the hole.

C. If the deviation of the hole exceeds one degree from true vertical at any point between the surface and the lowest minable coal seam, then the permittee, unless granted a variance by the chief, shall:

1. Correct the hole to within one degree of vertical; or

2. Conduct a directional survey to the lowest minable coal seam penetrated by the hole and, within 30 days, notify the coal owners or mine operators of the actual location of the hole.

D. All surveys conducted on the hole shall be filed with the chief at the same time the information is filed under 4VAC25-101-140.