30 CFR § 57.22229 Weekly testing (I-A, III, and V-A mines).
(a) The mine atmosphere shall be tested for methane and carbon
monoxide at least once every seven days by a competent person or an
atmospheric monitoring system, or a combination of the two. Such testing
shall be done at the following locations:
(1) The return of each split where it enters the main
(2) Adjacent to retreat areas, if accessible;
(3) At least one seal of each sealed area, if
(4) Main returns;
(5) At least one entry of each intake and return;
(6) Idle workings; and
(7) Return air from unsealed abandoned workings.
(b) The volume of air (velocity in Subcategory I-A mines) shall be
measured at least once every seven days by a competent person. Such
measurement shall be done at the following locations:
(1) Entering main intakes;
(2) Leaving main returns;
(3) Entering each main split;
(4) Returning from each main split; and
(5) In the last open crosscuts or other ventilation
openings nearest the active faces where the air enters the return.
(c) Where such examinations disclose hazardous conditions, affected
persons shall be informed and corrective action shall be taken.
(d) Certification of examinations shall be made by signature and
date. Certifications shall be retained for at least one year and made
available to authorized representatives of the Secretary.
[52 FR, 24941, July 1, 1987, as amended at 52 FR 41397, Oct. 27, 1987]