MOUNT VERNON — Columbia Gas Transmission Corp. owns hundreds of miles of underground pipelines that feed natural gas to all areas of Ohio. The lines are under constant survailence for leaks, damage or other problems that can affect the safety of the lines. Much of the surveillance is done by pilots flying light aircraft along the lines, looking for problems.

When closer scrunity is called for, a helicopter and a crew are called in to give a line a complete checkup. Today, a low-flying helicopter is patrolling the area of South Main Street, the southeastern areas of the Mount Vernon school complex, the Mount Vernon Nazarene University and across the county to areas of Hopewell Road.

The 10-inch gas pipeline being patrolled branches off from another cross-crountry line supplying Mount Vernon.

“This line carries 210 pounds per square inch gas pressure, reduced from 350 pounds on the main line,” said Columbia Gas Team Leader Tracy Huffman, based at Treet Columbia Gas Station at Homer.

Pipeline engineer Mike McCutchen will perform the testing work. To measure for leaks, the crew employs FLIR — forward looking infared radar — pronounced “fleere.” McCutchen said the radar detects methane gas, which makes up a large percentage of natural gas.

The crew also uses instruments to test the pressure in the line, as well as visual inspection, looking for anything that might cause physical damage to the line.

According to Bell Jet Ranger helicopter pilot Wesley Mitchell, the crew flies at an altitude where it can make a landing in the event of engine failure.

“Over populated areas we fly about 300 feet high, over an open field, down to 50 feet,” he said.