30 CFR § 57.22230 - Weekly testing (II-A mines).
§ 57.22230 Weekly testing (II-A mines).
(a) The mine atmosphere shall be tested for methane 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) Active mining faces and benches;
(2) Main returns;
(3) Returns from idle workings;
(4) Returns from abandoned workings; and
(5) Seals.
(b) Where such examinations disclose hazardous conditions, affected persons shall be informed and corrective action shall be taken.
(c) Certification of examinations shall be made by signature and date. Certifications shall be kept for at least one year and made available to authorized representatives of the Secretary.