The most advanced level of training outlined in the NFPA 1670 and 1006 standards. This course is designed for per- sonnel responsible for rescue and recovery operations in more complex environments. At this level personnel shall identify and understand the limitations and removal of manufactured protective systems, as well as learn procedures for monitoring the atmosphere in all parts of the trench. Additional topics include the limitations of supplemental sheet- ing and shoring systems; procedures for adjustment of protective systems based on environmental conditions; de- watering, rigging and placement of isolation systems.