WDØM - Pagosa Springs, CO

Pagosa Springs, Colorado








Welcome to WDØM's Tower Project

This tower installation was different than any other I have done. The problem was that just six inches under the soil was solid bedrock. I looked in several places, digging test holes, in the immediate area where I wanted to put a tower. I found nothing but solid rock. Fortunately, it was all fairly flat and appeared to have no fractures.

I cleared an 8' x 8' square, and eventually decided that this was to be where I would put the tower. Not being able to dig a hole without blasting, I checked on the web and found several references to towers being installed using the rock as a base. It involves drilling holes, putting rebar in the holes, and holding them in place with epoxy or rock cement. It also involves an element of faith, hoping that the rock is solid, heavy and deep!

Step One - Drill 25 Holes!

  • I borrowed a Bosch Hammer Drill from my cousin, and used it to drill 25 holes in the rock, each about 6 inches deep, and about one foot apart. It took two days to get them all drilled.

  • I was lucky because the rock was fairly flat across the surface where I would place the tower base, and there were no major fractures of any kind. Despite not having luck on my side and being able to do a "traditional' installation, nature worked with me in the end.

  • Step Two - Cement Rebar in Place

  • The next step was to find an epoxy to set the rebar in place. All the epoxy I found locally had expired and wasn't usable - if you pursue this type of installation, check the expiration date on the epoxy before you use it!

  • I selected a product called "Rockite", a super strong cement used to hold anchors in place in cement or rock. It works great, and sets up in about 10 minutes, fully drying in about an hour. It's designed to hold industrial equipment to cement floors. I figured that this would do the job!

  • Step Three - Build a Rebar Cage and Frame

  • After the cement/epoxy holding the vertical rebar lengths has dried, install the horizontal rebar rods to form a cage and wire them in place to make it fairly rigid. The rebar is primarily there to keep the concrete from cracking when it dries, as well as add some strength to the poured concrete.

  • You will need a frame to hold the concrete when it is poured. I used 4' x 8' plywood supported by 2" x 4" lumber. I can't emphasize how important it is to make the frame as rigid and reinforced as you can. Concrete is HEAVY!

  • Step Four - Install the Tower Base

  • Install the "J-Bar" bolts for the tower base in the rebar cage so they are vertical, and aligned with the tower base plate holes. Refer to the manufacturer's engineering drawings to be sure you have it right. Once the concrete has dried, you're not going to be able to move them.

  • Set the tower base plate on the J-bolts and secure it in place. Be sure to use levelling nuts and washers so you can adjust the base plate height to make it absolutely level. I used 2' x 4' lumber with small strips of wood attached to the side of the frame to support the base plate at the appropriate height. Secure it in place so that when the concrete is poured, it doesn't move.

  • Step Five - Review Step 3 - Concrete is HEAVY!!

  • Concrete weighs just over 4000 pounds per cubic yard! I used 5 cubic yards in this project - 20,000 pounds of heavy concrete! This picture shows a small "blowout" on the bottom corner of the frame. Despite using numerous braces, including running rebar completely through the frame horizontally and bending it to strengthen the frame, and using heavy ropes to tie the corners posts together, I still had a small blowout when the nails popped loose from the stress. The concrete was dumped at this corner first, instead of pouring it at a uniform depth, causing a significant stress on the frame. Lesson learned.

  • Fortunately, some nearby rocks and some long screws were put to use to brace the bottom of the frame, and screw the frame back together as best I could. It worked.

  • Step Six - Patience

  • The concrete was poured, the frame held, and now it's time for patience to let it dry. I used a small section of 2' x 4' to smooth the surface of the concrete. When it dried a bit more, I used a stainless steel "float" to finish off the concrete - don't forget to put your callsign in the concrete before it dries to commemorate this occasion!

  • Step Seven - Raising Fixture

  • After removing the frame from the concrete, I used my truck and a "come along" to move the tower over into rough alignment with the base (it was actually nice to have a little snow to help the tower slide easier). I mounted the raising fixture on the tower base, and then used the winch line to move the tower toward the base. Since my concrete base is elevated far more than normal, I used some 2 x 4 inch lumber as a ramp to slide the tower up and on top of the concrete base - it worked perfectly! I bolted the base into the frame, and I'm now ready to install the rotator, antenna and coax. Can't wait to get on the air!

  • Step Eight - FINISHED!!

  • I mounted the antenna on the tower (see the "SteppIR Antenna" link at the top of the page for details) and now it's up in the air! Placing the antenna on the tower was an interesting challenge, but it turned out to be a great combination - US Towers TX-455 and a SteppIR 4 element antenna! See you on the air!

    73, Joe
    WDØM