Compliance sampling.

(a) The operator shall take five valid respirable dust samples for each part 90 miner within 15 calendar days after:

(1) The 20-day period specified for each part 90 miner in §90.100 (Respirable dust standard);

(2) Receipt of notification from MSHA that any respirable dust sample taken in accordance with §90.208 (Bimonthly sampling) exceeds 1.0 milligram per cubic meter of air or the respirable dust standard established by §90.101 (Respirable dust standard when quartz is present); and

(3) Implementing any transfer after the twentieth calendar day following receipt of notification from MSHA that a part 90 miner is employed at the mine.