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East Road Gas Line Tunneling Underway

on September 15, 2012 - 12:53pm
The gas line tunneling project near the Crossroads Church on East Road involves placing both a 6 inch and an 8 inch line in separate tunnels. It is cheaper to dig a tunnel for the new gas lines with a $350,000 machine than to do it the old fashioned way by digging a trench. Tunneling doesn't wreck driveways and sidewalks. This strange machine in the photo bores a tunnel underground for placing the new gas lines. One crew member operates the machine with a support three or four person support team. The pipe extending from the front of the machine is the drill pipe that is connected to the boring bit that drills the hole. The drill pipe enters the earth in the hole behind the blue circle, which is an end plug for the new 6" gas line already in place. Photo by TK Thompson/ladailypost.com
A side view of the boring machine. The green hose is the water line that serves to lubricate the drill bit while boring or reaming the hole plus flushing the earth from the bore-hole. The angled rack on top of the machine holds 10-foot sections of drill-pipe. The machine automatically adds or removes drill pipe depending upon whether it is drilling a hole or pulling the drill bit string back out. Photo by TK Thompson/ladailypost.com
 
The operator sits in the shade while running the machine. The drill pipe extends from the front and is rotating and advancing to bore the hole. The hole can be "steered" by the operator to go where he chooses. Photo by TK Thompson/ladailypost.com
 
A worker changes the drill bit on the end of the drill string. The initial bore is about 3 inches to 4 inches in diameter and extends about a half block underground. The end of the drill string is located electronically and a backhoe is used to excavate a pit so the drill bit can be pulled out above ground for bit changing. The large cylindrical object near the worker's feet is a reaming bit used to expand the bore hole up to 8 inches in diameter. The crew reamed this hole from 3 inches to 4 inches in diameter up to 8 inches and a half block long in about 40 minutes. Photo by TK Thompson/ladailypost.com
 
The reaming is in place and is being pulled back into the borehole by the drilling machine a half block away. Photo by TK Thompson/ladailypost.com
 
To commence reaming, the bit is now rotating and water is spraying out of the bit to remove the cuttings and lubricate the reaming bit. The reaming bit will now be pulled all the way back to the drilling machine enlarging the bore hole up to 8 inches in diameter. After reaming is completed, the drill string will be extended again to the far hole, a continuous section of new gas line is attached to the end of the boring bit, and the line is pulled to the other end where the drilling machine is located. The new section of gas line is then joined to another section that has already been placed in the previous tunnel, making a continuous pipeline. Photo by TK Thompson/ladailypost.com
 
This machine is used to join sections of the High Density Polyethylene (HDPE) pipe. Individual sections of pipe arrive by semi-trailer to the jobsite and are about 30 to 40 feet long. The ends of the sections to be joined are heated to soften the HDPE and then jammed together hydraulically to form a seamless bond. The black pipe is the 8-inch in diameter high pressure line. The wall thickness is 1.25 inches and it is pressure tested after joining at 250 psi. Photo by TK Thompson/ladailypost.com
 
The completed joint in the 8-inch high pressure line is made. The workers know the joint has been successfully made when a bead of HDPE is visible on the outside of the joint. Photo by TK Thompson/ladailypost.com

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