Advice needed on equipment to install fenceposts in lava-rocky soil (Holualoa: rent, buying)

[BuildBliss]

As the title says, my Holualoa property has lava-rock in excess. How does one put in fence posts? I attempted to drive the steel T-posts and the ground just laughed.

I would happily rent a bobcat and auger to dig the posts if I was more confident that the auger would succeed. Do I need a hydraulic breaker? Yikes...

At some point I have to get a septic system in this hard stuff. Can a vehicle as small as a bobcat rip the lava-rock filled ground here or is this a task for a much bigger machine like a dozer?

[Grassyknoll]

Originally Posted by BuildBliss

As the title says, my Holualoa property has lava-rock in excess. How does one put in fence posts? I attempted to drive the steel T-posts and the ground just laughed.

I would happily rent a bobcat and auger to dig the posts if I was more confident that the auger would succeed. Do I need a hydraulic breaker? Yikes...

At some point I have to get a septic system in this hard stuff. Can a vehicle as small as a bobcat rip the lava-rock filled ground here or is this a task for a much bigger machine like a dozer?

You can drill large holes (approximately the diameter of your t-posts) and then drive them in.
If you property has previously been ripped, you might be able to dig with a small backhoe, but if it is untouched, it'll likely need to be hammered.

[BuildBliss]

Originally Posted by Grassyknoll

You can drill large holes (approximately the diameter of your t-posts) and then drive them in.
If you property has previously been ripped, you might be able to dig with a small backhoe, but if it is untouched, it'll likely need to be hammered.

So if I understand, you describe using a drill or auger, by hand to take out a small hole just bigger than a T-post. I can rent one on those I expect, with auger style bit.

This property has not been ripped. I may at some point need a hydraulic hammer on a backhoe, if I get your point, to begin to put large posts or a septic system in.

[terracore]

If you have power you can buy or rent an SDS Max drill with the appropriate sized bit and it will make installing the T-posts easier than pounding them into hard dirt.

If you don't have power and time is on your side you can use a battery powered SDS Plus drill but plan on it using the entire battery for each hole, and you'll need to let the drill cool down before starting another. You'll have to get a drill bit like this one:

https://www.amazon.com/gp/product/B0...f_=as_li_ss_tl

Ryobi makes an 18v SDS Plus drill that is rated up to 1" holes. It can handle the larger size needed for T-posts because the lava rock is generally softer than reinforced concrete. They make a smaller model for .5" holes and you would just burn out the motor if you tried to use it for this purpose. I think Milwaukie actually makes a battery powered SDS Max drill but when I looked at it, was less powerful than the larger Ryobi.

Also, if you have power Amazon sells a jackhammer they will ship to Hawaii you can use for the larger holes for the corner posts. You will probably want to buy a wider bit than what comes with it: https://www.amazon.com/gp/product/B0...f_=as_li_ss_tl

Another good option is to just pay a fencing company to come and put all the holes in for you, since they already own the equipment it might be a better deal than you buying a bunch of stuff.

For the septic, you'll have to hire that one out. You have to use a licensed installer for the permits anyways.

[BuildBliss]

Originally Posted by terracore

If you have power you can buy or rent an SDS Max drill with the appropriate sized bit and it will make installing the T-posts easier than pounding them into hard dirt.

If you don't have power and time is on your side you can use a battery powered SDS Plus drill but plan on it using the entire battery for each hole, and you'll need to let the drill cool down before starting another. You'll have to get a drill bit like this one:

https://www.amazon.com/gp/product/B0...f_=as_li_ss_tl

Ryobi makes an 18v SDS Plus drill that is rated up to 1" holes. It can handle the larger size needed for T-posts because the lava rock is generally softer than reinforced concrete. They make a smaller model for .5" holes and you would just burn out the motor if you tried to use it for this purpose. I think Milwaukie actually makes a battery powered SDS Max drill but when I looked at it, was less powerful than the larger Ryobi.

Also, if you have power Amazon sells a jackhammer they will ship to Hawaii you can use for the larger holes for the corner posts. You will probably want to buy a wider bit than what comes with it: https://www.amazon.com/gp/product/B0...f_=as_li_ss_tl

Another good option is to just pay a fencing company to come and put all the holes in for you, since they already own the equipment it might be a better deal than you buying a bunch of stuff.

For the septic, you'll have to hire that one out. You have to use a licensed installer for the permits anyways.

Thank you, Terracore,

All good info and thanks for specific bit recommendations.

i have 15 posts to place about 10' apart and they head down a slope of 2.5/1, so I need to learn to wrangle a heavy roll and, I guess, stretch it as I unrolll it to keep the mesh of the field fence in a vertical orientation as I go down the slope. Seems hard but youtube is probably my friend.

[terracore]

Do you know what kind of fence you are using? Stretching the fence is the hardest part of the job for a DIY project. Your project suggested 150' of fence and most of the quality rolls of field fencing are 330' where I shop.

Unfortunately, my next fencing project is about a quarter mile.

[gemstone1]

And I complain about digging post holes in Virginia red clay with an occasional rock encountered !

[hotzcatz]

Would it be easier to shape and pour concrete fence posts? I've seen old fences made with concrete posts before. Not sure how they'd be anchored to the ground, though, without some sort of hole?

[BuildBliss]

Originally Posted by terracore

Do you know what kind of fence you are using? Stretching the fence is the hardest part of the job for a DIY project. Your project suggested 150' of fence and most of the quality rolls of field fencing are 330' where I shop.

Unfortunately, my next fencing project is about a quarter mile.

That's how long my water line is

I'm using a 330' roll of field fence with higher mesh density at the bottom than the top. And I miscounted; its 270 ft of fence needed and at 10' spacing (should it be 8' spacing) that's 28 posts. Uggh. But from my youtube research, it seems that end posts and posts at the hill's positive inflection points should be something more substantial than T-posts to anchor the fence and permit tensioning. so perhaps round treated wood fence posts with diagonal bracing at these special locations...?

I've seen cast concrete fence posts before, but wrangling that weight on a a slope approaching 3/1 is kind of daunting. And they each need a big hole.

[terracore]

Originally Posted by BuildBliss

That's how long my water line is

But from my youtube research, it seems that end posts and posts at the hill's positive inflection points should be something more substantial than T-posts to anchor the fence and permit tensioning. so perhaps round treated wood fence posts with diagonal bracing at these special locations...?

Whoever installed the fence where I live used treated wood posts in some areas and eventually they all rotted at the ground and broke so I had to replace them with galvanized steel. They probably work okay in a drier climate. I don't know exactly when they were installed but I estimate they lasted less than 15 years.

Here's a corner brace option using T-posts. I haven't tried the product myself but I was planning on trying a DIY version of it: https://www.lockjawz.com/ (scroll down to the corner brace kit).

I have used their spring wire clips, they do make the install go a lot faster.