Due to a Federal Energy Commission (FERC) requirement, EPNG continuously monitors the natural gas stream at strategic locations throughout the pipeline system. At such sites, the natural gas is monitored for Total Organic Sulfur once every 15 minutes (using method ASTM D 4468-85) and for H2S once every 30 minutes (method ASTM D 4068-94). These monitoring stations are located upstream and downstream of Navajo Station (at EPNG’s Gallup and Flagstaff stations).