What must the D/E Candidate announce to effectively complete the pumping operation in Drill #4?

To effectively complete the pumping operation in Drill #4, it is crucial for the D/E Candidate to announce that the operation is successfully finished and that safety cones have been deployed. This announcement signifies that all activities related to the operation have been completed safely and that the area is secured for both the crew and any bystanders.

The deployment of safety cones is an important aspect of maintaining safety in emergency operations. It alerts others to the fact that the area is being managed and that they should be cautious around the equipment and personnel. Announcing that the operation is finished not only communicates the end of that phase but also ensures that the entire team is aware that it is safe to proceed or wrap up their tasks.

Other aspects, such as water flow optimization, the tank being full, and pressure readings being stable, are important operational metrics but do not inherently signify the completion of the operation in the way that securing the area and confirming the end of activities does. Thus, the clarity of communication about the operation's completion and safety ensures that all personnel are informed and that safety protocols are followed effectively.