Porcupine problem

[AndyD]

I have had numerous problems with a remote water boosting station. About a year ago we replaced cabling and pipes that run down a mountain side. The old pipes were badly damaged by animal teeth, I suspected it might be rats at the time but I wasn't sure.

The new pipe which is HDPE class 10 and SWAcabling was installed inside another class 10 HDPE pipe as a sleeve to prevent further damage. I was called out again this week and the sleeves, the water pipework and the SWA cables are all badly damaged beyond repair. Sections of teeth damage around 30-40 cm long occur in many places, the pipework hasat least a dozen leaks and the SWA cables are stripped down to the copper conductors in too many places to repair.

The mountainside is in Cape Town and is steeper than 45 degrees and very hazardous to descend without ropes. It is heavily wooded with thick underbrush. I called in an 'expert', he was wearing khaki shorts and one of those hats with a roll down flap at the back so he must know what he's talking about. He reckons that the damage is caused by porcupines but he doesn't know how to stop them doing it.

I don't want to replace the system again without effective measures in place to prevent further damage. Trenching is impossible due to the high angle and the forest roots. There's no machinery can go down this slope. If these things can chew through calss 10 HDPE and the steel armour stranding of SWA cxabling then I'm fresh out of ideas.

I've never clapped eyes on a porcupine, I always thought they were a bit more substantial that a hedgehog but I think I may have underestimated the enemy in this particular battle.

Any suggestions would be gratefully received.

[desA]

Time to install a battery-powered energiser. This should have their quills standing up straight.

Install supply & return leads if earth conductivity is marginal. The leads can be simple bare wires - make sure they don't earth out.

Install a hot-box around the battery/energiser to prevent two-legged porcupine interference.

[Dave A]

Interesting. I didn't know porcupines had the gnawing habit. So they're actually rodents then.

I understand you can't bury the cable, but you could wrap it in concrete.

[AndyD]

@desA, Are you talking about a HV electric fence type unit? The sleeves are lying on the floor, won't the system just earth? I don't know how you could keep the wires insulated.

Interesting. I didn't know porcupines had the gnawing habit. So they're actually rodents then.

I understand you can't bury the cable, but you could wrap it in concrete.

Hi Dave,

I don't know if porcupines are rodents or not, I actually don't know much/anything about them, including if gnawing is a common problem with them.

Encasement was something I looked at but with the high slope angle the weight of the concrete would cause creeping, it would need to be anchored regularly with footings or piers. Just bucketing it down the mountain would be a task, it would be an expensive installation.

I also looked at screwed galv steel pipe as a sleeve but again anchoring would be the problem, it would just want to slide downhill. Corrosion would also be an issue and if there ever was a leak in future it would be very difficult to pinpoint inside concrete or steel sleeving.

The total length of the run is 145 meters. There is a level 20 meter section at the bottom and a level 30 meters at the top. The steep section in the middle is around 100 meters in length and the altitude rise of this section is about 80m. Thick tree coverage means there are large branches falling regularly so steel being inflexible might not be suitable.

[daveob]

fight the porcupines with a porcupine.

thought of using something like the spike security strips you place on top of gates and walls ?

[daveob]

also found this blog via google :

http://rouxpecans.com/blog/?paged=3

seems that all you need is some smelly stuff to ward them off.

[Dave A]

Well that confirms it then - they're rodents.

Rodents love gnawing on plastic. It's a great material to keep their continually growing teeth under control. (For anyone reading that blog entry, they're not after the water in the pipe )

With your terrain challenge, a physical barrier that would keep them away from the pipe seems to be the best option. Something like a grid mesh cage around the pipe perhaps? You get that fairly rigid mesh they use for animal traps and such like. Rust will still be a problem, but stopping the porcupine damage and all the consequences of that should make it worth it - even if you do have to replace it every few years. It should last about as long as bloudraad, though. You're going to need a wire mesh of that kind of thickness as the porcupines are bound to gnaw on that too.

It'll probably need a spacer setup too so that the teeth can't get to the plastic through the mesh.

[AndyD]

It is surmised that they dig to find the pipe because they can sense the water in it and need a drink.

Well that means burying the pipe is a waste of time and money. Maybe a night on the mountain with my Glock and a good recipe book is the way to go.

[Dave A]

Well that means burying the pipe is a waste of time and money.

I doubt they'll dig for it if it's deep enough. There should be enough natural gnawing material handy on the surface in a natural habitat.

Maybe a night on the mountain with my Glock and a good recipe book is the way to go.

You did say this is in Capetown, right? The bunny huggers will kill you.

[AndyD]

You did say this is in Capetown, right? The bunny huggers will kill you.

Lol, I won't be shooting bunnies (unless I get really hungry) :-)

[desA]

@desA, Are you talking about a HV electric fence type unit? The sleeves are lying on the floor, won't the system just earth? I don't know how you could keep the wires insulated.

If the ground is reasonably moist, then you only need the live carrier - use the ground as return. As long as the live line is kept off the ground, it should be fine. I'd make a few pipe sleeves/insulators to keep it on top of your water pipes.

An alternative is to even use a few lightly-clad lines running over your pipes. When porky bites again, it will get the full knock of the energiser on the first decent bite. In this case, use ground as the return - this is standard practice on farms.

You could use a smallish energiser - they are not that pricey. Give a nasty kick.

[desA]

also found this blog via google :

http://rouxpecans.com/blog/?paged=3

seems that all you need is some smelly stuff to ward them off.

What under-arm deo does this Julius Malema character use?

[AndyD]

If the ground is reasonably moist, then you only need the live carrier - use the ground as return. As long as the live line is kept off the ground, it should be fine. I'd make a few pipe sleeves/insulators to keep it on top of your water pipes.

An alternative is to even use a few lightly-clad lines running over your pipes. When porky bites again, it will get the full knock of the energiser on the first decent bite. In this case, use ground as the return - this is standard practice on farms.

You could use a smallish energiser - they are not that pricey. Give a nasty kick.

Thanks for the suggestion (wasn't sure at first if you were being serious). I'll definitely look into it.

[wynn]

Would lifting the pipe and cable off the surface be a solution?

Depending on height required simply bend a pigs tail to one end of a length of rebar, drive the rebar into the ground next to the pipe/cable, lift and clip it into the pigs tail. support if necessary.

[AndyD]

Nice idea Wynn, I hadn't thought of elevating the pipes. I'm not sure if the buggers can climb or fly though.