In 7 hours, with minor digging, two of us buried 1000' of sch 40 1" PVC
pipe 18" deep, Since the process worked so well and is extendable to
conduit, direct burial coax and radials I thought I'd pass along the
technique. (No claim here for originality, this technique is used
commonly on ranches and farms). The concept is to use a single ripper
blade on a tractor to pull the end of a length of whatever, down to the
penetration depth of the blade tip.
Admittedly, not every ham has access to the 55 hp John Deere 5310
tractor with a three point hitch that we used. However, the approach
should scale from lawn tractors for radials to small garden tractors for
coax to small/mid sized Kubotas for conduit which can pull almost what
my tractor can pull.
We used a single ripper blade three point hitch attachment, with a hole
drilled in its bottom part about 1.5" up from the lowest point of the
tip and about 1" from the rear edge at that elevation. A galvanized
shackle, in this case a 3/4" pin connected a cable pulling grip. These
are used commercially for large diameter overhead/conduit power lines,
cables or multiconductor telephone cables. They are like the familiar
Chinese finger torture toy, the harder one pulls, the tighter the woven
cable strands clamp. New, these aren't cheap, but they are usually
available on ebay at a good price. The best ones have a swivel and
bullet shape termination at the pull end of the grip. This makes them
slide easier through the ground, overhead pulley assemblies, or
conduit. The usual Kellem power cord strain relief which works the same
way could be threaded into a pipe fitting, cross drilled and wired to
the shackle and would probably work almost as well at a fraction of the
cost. Pulling grips/Kellems are made for specific diameter cables, each
one has about a 2:1 range.
The day before, we glued together 200' long sections (10 x 20') of
pipe. A day later, after the joints had fully hardened, we started with
a small hand dug hole, attached the grip over a pipe cap (not glued) and
15" of pipe and pulled the full 200' into the ground. The 200' pulled
easily through Northern CA adobe (which still has some moisture left in
it this year) at an depth of 15 to 20 inches. At the 200' ends we dug a
small ditch, unhooked the grip, and used that ditch as the start point
of the next 200' section. After the 1000' was all in the ground, we
glued the sections together (we left a little overlap and cut to length
in the small ditches). In this situation, the tip of the ripper was a
larger (25%) than the diameter of the pipe and I think that is necessary
to push the soil apart enough so the pipe pulls easily.
While I prefer elevated radials, they just don't work in some
situations, like my pasture. Since they only need to go a few inches
into the soil, this approach would work with a lawn tractor and a home
made ripper, probably 1/4" steel plate is more than strong enough and
wide enough for radials to not need a widened tip. A small dug hole at
the base of the antenna could be the start point for pulling all of the
How long can the pipe or cable pull be for a single pull? That likely
depends on a lot of factors - strength of the item pulled for sure, how
slick it is, is the soil sticky or soft, etc. In my case we thought we
might be able to pull 300' sections of 1" PVC, which is slick and the
adobe broke into clods. (b.t.w. pull conduit with the bell ends last)
We speculated that wet sand might be the worst soil. A steel
messengered CATV hardline ("figure 8 cable") would probably go a long
way in one pull (1000' ?).
On a warm day 1" PVC is fairly flexible, we had one section of about 75'
radius. Of course, the tighter the radius the more stress and ground
friction, so there are some limits.
This 1000' of pipe finished the last section of a 4000' spring line, the
other parts were done by Ditch Witch and backhoe over the last couple of
years. We coulda/shoulda have done most it with the cable grip/ripper
process. Live and learn, trial and error.
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