MSHA’s recent program information bulletin show the following engineering controls and work practices as offering promise in reducing a miner’s noise exposure:

Automated dust collection system or actuation of the dust collection system motors only during drilling, or use of administrative controls to accomplish the same task

Exhaust conditioner (water box) and/or manufacturer-recommended exhaust muffler

Controls for optimizing the drilling parameters (drill feedback system)

Water misting system through injection of a small volume of water in a mist form into the drill hole clearance system

Grommet to isolate the drill steel and chuck

Acoustical liner in the tool tray

Damped drill steels

MSHA considered the following engineering control and work practices proven in reducing miner’s noise exposure around roof bolting machines:

Wet drilling – where it can be implemented due to the roof bolter design and when compatible with the geology and mining method

Sharp drill bits

Starter drill steel to begin the hole

Straight drill steel, that is one piece and with thick wall, if conditions and dust collection allow

Replacement of worn or defective drilling components, such as drill pot brushings or bearings, worn steel and bent steel

Maintenance of manufacturer-recommended drilling parameters for thrust, torque, and rotational speed