Long poles + dirty holes

Construction people: I want to sink two 18' (above ground) wooden poles. What do I need for this?

From my own (limited) fence-building experience, I know I'm supposed to sink a pole about a third of the above-ground height, into the ground. So this'd mean I'd need 24' poles, and six-foot holes. Will that be sufficient to hold a 600lb+ log upright? I could imagine needing to go even deeper as the weight of the pole, and thus the involved forces, become larger and the dirt doesn't become any harder.

Second question: How do you dig a hole that deep and set a pole that size in it? I imagine that there are specialized augers and polesetters for this.. but I shudder at the thought of rental costs for just two poles. When I built my fence I rented a power auger from Home Depot but it was only useful to about 3' depth. I don't even know where to start looking for something that can do 6 - 9'. Or where to find a machine that can lift a tree trunk and stick it vertically into the ground.

I did read about a "before-power-tools" method that involved digging a long descending trench down to the needed depth, and then dragging the pole into the trench and eventually pulling it upright using the trench wall as a lever. However... this seems a) like a whole fuckload of work and b) a really great way to crush my truck with a tree that got pulled too far.

Who knows what?

 

How big a pole...Diameter? Like a telephone pole or a 6x6?

Will they be attached or guy'd to anything or free standing? What kind of load will they see?

As a FYI I am digging holes for 6x6 pole bar poles. Mine will be 16-20' long. For frost around here I ahve to go down about 4 ft and pour a concrete footer. But these posts are tide together with girts, headers and trusses.

A wood pole guide for telephone poles shows 6' deep for up to 40 ft, so your on track there.

For 1-2 poles either dig by hand or rent a mini-excavator

 

You need a diesel powered digging tool.

 

Mini-telephone-pole, yeah. I want to build a ranch-style gate entrance with probably a 18'-high crossbar. I'm picturing 8-10" diameter poles.

I hadn't even considered frost tbh. I'll look up our frost depth here in PNW.. I don't expect it'll be more than a foot though. But I don't really know how to reason about what frost will do to the design here.

 

Nah.
A few of these would work

 

As long as the grunts stick around to fill it back in

 

OT, but it always amazes me anytime I see pictures of relatively-new soldiers. We always think of soldiers as these grizzled, capable, hard iron men... but no, now that I'm 35, they're children. They're grizzled, capable, hard iron... children. Fuck war.

<awkwardly and self-consciously steps off soapbox>

 

Fuck war indeed. Keep in mind the public thinks that everyone in the military is the tip of the spear, just kicking doors and stacking bodies.

In reality a very tiny part of the modern military is actually directly engaging the enemy. Most are filling essential roles supporting the infrastructure behind the scenes. In my opinion, that makes the loss of life in modern IED warfare more appalling. Many of those killed never wanted to take the fight to the enemy. They wanted college money and job skills and had the balls to accept some risk to achieve their goals.

The guys who make their living jumping from airplanes to assault HVT’s and gun it out with insurgents are living their dream. If they perish, it will be a hero’s death, lying in a pile of brass, gripping a Spyderco. Is that less tragic than a supply clerk dying in a convoy with their head down and fingers crossed on the MSR? I honestly have no idea.

Fuck me. You really sucked me into your tangent.

 

I'd go down ~6ft maybe 16-20" diameter, pour some concrete to make a footing and set the post.

rent a skid steer with auger attachment and use it to dig the holes and help lift the poles.

 

The cross bar helps, but whdn the gates open you will have a very significant excentric load. Soil composition is a factor too.

 

I’ll be 50 next week, and seeing that pic reminded me of Xmas ‘87, when my brother gave me a 2nd ID patch sent from Korea that year as he couldn’t come home for the holidays.

I sewed that patch on my Levi’s jean jacket and proudly told all my friends where it came from. I still have it.

A long time ago.

 

10% + 2' is a standard rule of thumb. Deeper is better. So in your case 4' is good as long as you tamp the dirt around the pole after you plumb it. Preferably a hydraulic tamp and in layers. One person tamps while another is throwing dirt in. A hand tamp will work. You can also pour foam or concrete and not have to tamp. To plumb it you will get 90 degrees off the boom and you hold your stringed plumb bob in line with the middle of the bottom of the pole. Have the operator make adjustments until your string is dead nuts in the middle of the top of the pole and middle of bottom of the pole. Then do it again in line with the boom.
You can dig the holes and set those poles with a mini excavator or a backhoe.

 

That is the rule of thumb for a utility pole. For a gate post, 1/3 to 1/2 of the height.

 

To add to this info ^^^

Why would you even want to use a wood pole for an operational gate?
Makes much more sense to use steel for a gate post...
Easier to work with and a helluva lot stronger...

 

I don't know that he is having a swinging gate on it. I'm just picturing 3 poles, two vertical and one across the top like some old west entrance to a ranch.

 

Also, I doubt the gate is 12 foot tall. The gate load is still a function of gate height and length.

dude, I love this place but find a local expert.

 

Fair enough, a power pole also holds 10X more load than a wood pole with a couple hundred lb. gate. Additionally he did say something about a crossarm on top.

 

Rent a min-ex hat will dig 10’ then lash the pole to the bucket for the tip in.
If the bucket goes down 10’ it’ll go up nearly the same

 

Rent a mini excavator with an auger attachment. Most of those in the 10k lb class will drill 10-12' of depth without extensions. Another option would be a skid steer with auger attachment, most of those will get to 6-8' without adding extensions, or chase down a local power company and see if they would drill and set the poles on the cheap in their less busy times. Stone will help stabilize the poles on the refill.

 

looked at some 20' long precast fence posts that weighed around 1700lbs each... engineering showed a 2' wide bore by 8' long depth (min)