Anchor pulled out, with us on the tower!

Discussion in 'Incident and Near Miss Discussions' started by Richard Bell, Jan 20, 2016.

  1. Richard Bell

    Richard Bell Friend of the Community

    This accident happend a long time ago, in the summer of 1969. I took a new job with a contractor that usually did AT&T self-supporters. This project was a 450' tall, 36" face cable TV tower in Marble City, OK. Our task was to install a new set of torque arms up around the 400' level and install a new 8' x 12' reflector above the torque arms. We were also to replace the majority of the guywires and plumb and tension the tower. I set up the transit to start the P & T and the tower was 8' out of plumb. It was straight, but leaning eight feet. My boss was really upset that the tower was so far out because it was going to take a couple of extra days to get it plumbed and there were only three of us in the crew. I assurred him I knew what to do and leave me alone and we would get it done.

    We had to go through the process of taking up the wires on one side and letting out on the other and had to add some guywire pieces with cable clamps to have enough to let out in order to get plumb. During this process I noticed that a couple of the anchors had about 12' square concrete pads on them but the others didn't. I thought it was odd, but there was nobody around to answer why this was, so I forgot about it. We went ahead with the work and plumbed the tower, installed the new torque arms, replaced the smaller guywires and installed the reflector. At days end, all we had left to do was to do the path alignment on the reflector and downrig.

    The next morning, Saturday, the wind was blowing out of the north about 20 mph and it was spitting rain. The clouds were so low they blocked out the top of the tower. The technician arrived from Ft. Smith and we decided to go ahead and do the alignment and down-rig so we could get back home. Levi and I got on the ball and Bird hoisted us up the tower. I left the ball hanging and we loosened the stiff arms on the reflector and I heard Bird hollering up the tower. I didn't understand what he was saying and I was busy, but he kept on hollering and I understood him to say, "I thought you said you knew how to plumb a tower". I looked down the tower and it was leaning a good twenty feet to the south. At first I thought, Geez, that transit must really be out of calibration, then I realized immediately that this was an absurd thought. I looked out at the outside north anchor, and there it sat, on top of the ground about fifteen feet in front of the hole it used to be in. My mind was racing at this point and I told Levi that we were in serious trouble. We need to start unclimbing this thing right now, but climb as smoothe as you can. I shackled the ball off to the tower and we headed down.

    We immediately pulled the winch line off the main winch and drove the truck around behind the failed anchor and hooked onto it just for additional security. The technician called his office and they sent out a small drilling rig with 18" auger that would only dig 3' deep because of rock. We reported the incident to Bud Duvall who was the tower engineer for Utility Tower and he designed a new anchor which consisted of about a dozen holes around the exposed block of concrete and a 20' square pad three feet high.

    The original anchor lasted for seven years before it pulled out. There was less than a cubic yard of concrete in the anchor and the deepest part of the hole was 42" below grade, and the hole was shaped like a teacup.

    Since that incident, I have had a healthy respect for the integrity of the pipe tower legs. Although they are more limber than solid rounds, they are a very efficient shape for a compression member.

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