What should occur if water or roof falls close a bleeder return?

When water or roof falls close a bleeder return, a significant increase in air supply is required to maintain proper ventilation in the mine. Bleeder returns are critical for ensuring a continuous airflow which helps dilute and remove harmful gases from work areas. If an obstruction occurs due to water or a roof fall, there is a potential for air quality to deteriorate, which can lead to dangerous conditions for miners. Increasing the air supply allows for the restoration of effective ventilation, helping to ensure safety by providing fresh air and reducing the concentration of any harmful gases.

This response is essential because it emphasizes the importance of proper ventilation management in underground mining operations and the need for proactive measures to ensure miner safety.