April 5, 2012

A Major Blowout

We made our first attempt at charging the irrigation system on Tuesday, both the pumps and new actuator valves in the pumpstation fired up and operated as they should.  However, it didn't take long to realize that we weren't building pressure and something must have blown out.  Sure enough, left of 2 green, in the scarp that is sliding into the coulee, were a couple of good bubblers coming up out of the ground.

Although we very thoroughly blew out the irrigation system last fall, left of 2 green the mainline dives down from the fairway before coming back up to 3 tees, creating a large dip in the pipe.  Every remaining drop of water in the line from all of 1, 10, and 2 fairway drains back down to this area.  Apparently, there were still a few drops of water that didn't get blown out....

Fortunately, we still have 10,000 lbs of Bobcat T750 on site compliments of Florians, so the digging went pretty quick.  Also, since we were way out in the rough, we didn't have to worry about keeping this project very tidy.  All told, by the end of the day on Wednesday we had dug up and pulled out 160 feet of PVC that the frozen water inside of had completely shattered.  Amazingly, while I was digging, I started to think how much sense it would make to add a stub off the mainline in the lowest spot that would allow us to drain that section of pipe in the fall.  No more than 5 minutes later I dug up an old buried valve box, about 8" below the surface.  Inside the box was an old gate valve, apparently someone must have had a similar idea a number of years ago.  Had I known the valve was there and it wasn't covered up with 8" of silt and sod, we would have been able to drain that section of mainline last fall and avoid all of this....

Piles of the shattered PVC that was removed
The old drain valve that could have prevented all of this...

However, this was really a two part story.  Yes, the mainline holds water in that low spot and needs a way to be drained in the fall.  However, I'm sure everyone has noticed that the entire left side of 2 green, the bunker, and the rough over there is slowly sliding off down into the coulee.  As the ground slides and shifts every year, the mainline is going to continue to break and slide downhill with it.

To mitigate this, we made the decision to reinstall HDPE (high density polyethylene) pipe instead of the traditional PVC.  HDPE pipe is significantly more flexible and shatter proof than PVC, allowing the new pipe to flex and move downhill with the enscarpment as it slowly works its way down into the coulee.  Also, we installed knock on fittings at the two ends where we connected the new HDPE pipe to the old PVC mainline system.  Each of these fittings has about 12" of play in it where the HDPE can actually start to slide out of the fitting before it becomes disconnected and leaks.  This, coupled with the flexibility of the HDPE, and the new drain valve that we added at the low point in the line, will hopefully keep this blowout from happening again, at least for while....

The end of the breaks on the old PVC mainlines, seperated close to
an inch on each end where the ground slide is pulling the pipe apart

A technician from Ferguson Waterworks in Fargo came up to fuse the
new HDPE pipe together.  The ends of the pipe are heated up until the pipe
begins to melt, then the two ends are rammed together while the melted
pipe re-solidifies, essentially fusing the pipe together.

The HDPE butt fusion machine.

One of the knock on fittings on the ends of the pipe where the HDPE
connects to the PVC, allowing the new pipe some extra room for movement
A view of the small scarp face left of 2 green.  Last summer this little slip
area was connected with grass all the way across, now there is a very
defined face of exposed soil where the ground is breaking off and sliding
into the coulee.

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