If you've got pocket gophers....

   / If you've got pocket gophers.... #22  
Charles, good thread. You still around? This is the best source of practical information I have found on how to go about this. Perhaps I can contribute a bit more from my experiences. On re-reading the thread, I see a few things I might try differently, but here's what I did last October, 2010.


I tried and failed with electic spark ignition, even with a Galligher B80 fencer (0.8 Joules, they claim it's good for 12 km of cattle fence) and various spark gap schemes including a sparkplug pulled from my chainsaw. With a proper mix of oxygen and propane it did not ignite dependably, and I often could not hear the spark. This was especially true after the first use, even if I then heated the spark plug to purge any moisture. I'm not entirely sure why, but suspect moisture suspended in the gas (from previous burns) and the dialectric strength of propane+oxygen are both factors. I could get dependable sparks in air, pure propane, and pure oxygen, even immediately after a successful burn. But not propane+oxygen. These tests were carried out with the igniter in the bottom of an open 30 gallon garbage can, the spark properly insulated from the can walls.

Rather than buy rocket igniters (nearest source would be 2 hours away), I used a paper match head plus 3 inches of 30 guage steel wire, unbraided from some picture hanging cable. Wrap the wire around the match head once, being careful not to let it cross over, and secure in place with light paper surgical tape (or perhaps hot wax). Leave the two wire ends sticking out each way from the match head.

To hold the match head, I used a one foot length of 3/4" HDPE black plastic pipe. Cut two notches in the end of the pipe across from each other, each about a half inch deep. Duct tape some Romex house wiring down the outside of the pipe, an alligator clip soldered to each of two wires from the Romex and each alligator clip placed near one of the notches. Now the match head wires can be held by the two alligator clips with the match head recessed into the pipe by the notches to protect it from the dirt.

I had the other end of the Romex soldered to a lamp cord, which I plugged into a 50' extension cord, and rigged a way to power the far end of that cord from a drill motor battery.

I have an Oxy-Acetylene kit, Harbor Freight #98958, bought on sale for around $90, complete with regulators, hoses, welding and cutting torches. Was not obvious to me, but the acetylene regulator will clamp directly to the 5 gallon propane bottle from a backyard barbecue set. So that plus a (large) tank of oxygen and we're good to go. The oxygen and propane tanks are strapped to a hand truck such as HF #95061 and the hoses are duct taped to the handtruck frame for strain relief. I use a board wired to the handtruck platform to provide a sufficiently large base for the propane tank.

Procedure is:

Find an active gopher run that goes deep, not just through the loose soil under the that row of bean plants they just cleaned out. Ideally, the run goes downhill rather than uphill if you have hilly terrain. If the run goes both directions, take out each direction one at a time.

Arm the HDPE pipe with a match head, being sure to squeeze the alligator clips firmly and then gently push on the match head to ensure it is held secure. Put the match head end of the pipe into the run, push rags or wads of paper around the pipe to seal the run (especially if the run may be headed uphill). Remove the welding tip from your torch, and plug the torch into the top of the HDEP pipe. Open both valves of the torch wide open.

I found that 35psi on oxygen, 10psi on propane, open for two minutes worked pretty well. A bit more propane and it tended to burn with a flame in the open air (at least after the initial explosion). A bit less propane and it would blow fine, but when I pulled out the HDPE pipe it would be getting consumed with fire in the excess oxygen. A good run can take much more than two minutes, but often as not the run turned out to be just a couple feet long and I couldn't afford to waste that much oxygen.

After the two minutes are up, shut down the regulators and pull the torch from the HDEP pipe (I generally give the hose a yank from about 5 feet away). Then run for the far end of that extension cord, put on ear muffs, adjust your cup, and apply 12 to 24 volts from your battery. Should be just like all those youtube videos.



A few issues to ponder:

Think hard at each step. You could get yourself killed.

Never ever use acetylene for this. Acetylene and oxygen together are extremely unstable, and can easily go off without a spark. What's more, acetylene is lighter than air and so won't decend into the burrow.

Stay on friendly terms with any neighbors. Let them know beforehand what the loud booms are about, invite them over to watch the show, offer to clear their garden. Think about what you're going to say when the sherrif pulls up in response to a complaint. Don't mess with this in any area where it would not be appropriate to fire a 12 guage shotgun.

There can be a whoosh of flame from holes most anywhere in the area you are working. Be ready to put out a grass fire. Watch the area for signs of fire long after you think you are done. If weather is dry, wet the entire area down first, and wait for any wind to die down before proceeding.

Something non-flamable might be better than my HDPE pipe, though I wouldn't use something I didn't want to get hit in the head with.

I was going after gophers, and some of the explosions were rather impressive. Bigger critters will have bigger chambers, and give much bigger booms.

Flames can remain burning underground long after the explosion in some cases. So keep in mind that it could blow at any time when adding oxygen and propane, even if you have moved to a new run (which might be connected). It's also easy to forget to pull the torch from the pipe before igniting, don't do that.

Since it can blow at any time, pulling the torch from the pipe before ignition is only a partial solution to the issue of having a backfire go up the hoses. Perhaps a very large welding tip to restrict explosions from pushing back up the equipment without unduly restricting the normal flow out would be in order. This would also keep dirt from getting into the torch valves. (I was running with no tip at all, I intend to find an old tip and cut the end off.) Perhaps special backfire preventers should be added to the hoses at the torch.

I was constantly spinning those regulator handles to turn the gas on and off, something may wear out eventually. Perhaps add a couple ball valves, mounted to the hand truck frame, in line between the regulators and the torch head. I wasn't inclined to get near enough the gopher hole to mess with the torch knobs, though re-reading Charle's account makes me think a 4 foot hose from torch to pipe might work out OK. Likewise, Charles's choice of wood instead of my HDPE would be less inclined to burn.


Propane will rot hoses designed for use with acetylene, though I suspect it takes time. Probably sufficient to disconnect and purge the hose at the end of the day. Hoses designed for propane can be obtained, try sundanceglass.

Some of the commercial units have manuals online, they are well worth reading.

Expect to use a lot of oxygen. I had two bottles on hand so I could run one out and then wait till the next trip to town before exchanging it.
 
   / If you've got pocket gophers....
  • Thread Starter
#23  
Since it can blow at any time, pulling the torch from the pipe before ignition is only a partial solution to the issue of having a backfire go up the hoses.

At least one of the commercial units I looked at had triple flashback arrestors... no doubt much safer but also adds to the cost of the units.

Now that I have cleared out all the pocket gophers I just get one on occasion that moves in from another place. I have had really good luck with this style of trap:

CinchGopher.JPG


Since the part that grabs the gopher sits well into the hole it is pretty effective if they are just coming for a look-see or if they are pushing dirt to plug the hole. The box traps I would find filled with dirt more often than not, this style I find filled with dead pocket gopher ;) Using the trap for the onesy-twosy pocket gophers is much faster than breaking out the blasting rig :cool:
 
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   / If you've got pocket gophers.... #24  
> Now that I have cleared out all the pocket gophers
> I just get one on occasion that moves in from another place.

Good to hear you're still going after those gophers.

We had a big rodent problem summer of 2010, gophers especially. Kind of got away from us. Spent several days going after them with propane, though most of my time was spent figuring out how. We've since cleared out the thick clover around the garden which seems to attract them even more than the vegetables, and will be going after them with traps. But good to have plan B available when things get out of hand. And it's been a good subject to bring up with other gardeners once we've finished up with talk of the weather.
 
   / If you've got pocket gophers.... #26  
Here in the orchard the gopher runs are too extensive to treat spot-by-spot. I can run a garden hose into a gopher hole for hours then eventually see a little mud far downhill. It might be worthwhile to hire a gopher-blaster firm to hit many spots at once. I don't think anything short of that would make any difference.

These mounds around the trees aren't from discing, the mounds are pushed up later by gophers. When I dig them up I find the mound is mostly cavities, often with chambers full of hoarded grass.

P1200670-023.jpg


Here's one (far left) where the mound is mostly freshly pushed out dirt. I'm sure my trees would grow better without the gophers. When I backhoe out a dead tree, much of the region that should be roots is gopher burrows instead.

P1200645-015.jpg


This ancient tree is nearly gone. The gophers have moved in.

57323d1151967748-gophers-trees-p1020722rgophersintree.jpg



Something new last year was coyotes digging up gophers. Over a month, suddenly gopher runs were ripped open everywhere. In this picture the gopher got away then later pushed more dirt out into the far end of the trench. The coyotes have moved on now, and the number of gophers seems to be the same.

P1600953-011.jpg
 
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   / If you've got pocket gophers....
  • Thread Starter
#27  
It might be worthwhile to hire a gopher-blaster firm to hit many spots at once.

You would have to call one but here they wanted $100/hour and my few acres was quoted at 4 hours..... it adds up fast. You won't get 100% kill the first time through so it might be cheaper in the long run to buy a factory blasting system than hire someone to come in. Especially since you get some coming in from other areas and need something for 'ongoing management' ;)
 
   / If you've got pocket gophers.... #28  
Have any of you guys tried using a gophers machine. It runs threw the ground and puts ot poison. Thats what i use on my place.
 
   / If you've got pocket gophers....
  • Thread Starter
#29  
Have any of you guys tried using a gophers machine. It runs threw the ground and puts ot poison. Thats what i use on my place.

That is what the farmers use around here... I don't have a place or a tractor that big :D

Since I am in the county part of my property taxes go towards pest control which includes gophers. I had them come out and treat with poison but didn't notice a difference. The ground was so torn up with gopher mounds it was hard to tell if any activity stopped. With the blasting you usually tear up the runs and the gophers have to come back and start repairs so you see any new activity.
 
   / If you've got pocket gophers.... #30  
That is what the farmers use around here... I don't have a place or a tractor that big :D

Since I am in the county part of my property taxes go towards pest control which includes gophers. I had them come out and treat with poison but didn't notice a difference. The ground was so torn up with gopher mounds it was hard to tell if any activity stopped. With the blasting you usually tear up the runs and the gophers have to come back and start repairs so you see any new activity.

Yea i understand that. I use them on my hay fields and all my pasture land. I have a few customers i do it for also because like you they only have a small amount of land.
 

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