Tips on vertical posts?

[ndnewbie]

I am building a 140 x 70 outdoor riding arena, which will require about 40 posts. I am putting 5-6" 8' posts, 3' down into clay.

I have found that by using a 6" auger, I can save about 70% of the work involved, by not having to backfill the hole much. (Its terrible trying to backfill clay.) I just drop down a sack of quickcrete around the post. However, when digging that precise a hole, I have found it has to be exactly vertical, since there is too little play to make corrections (which is maybe why people don't do this).

As I drop the auger and drill, the reach on the arm grows, tipping the bit past vertical. I can back up to compensate, but have had difficulty getting it right. I suppose a person could put the bit a few inches in front of vertical, which I might try, after working with a plumb bob to see how far forward the arm moves.

Has anyone already solved this issue, other than using a bigger bit leaving more play? (The one situation where more play means more work.) Thanks for any thoughts.

 

[mouse]

not too sure i'm going to answer your question but here goes.

if i am placing posts then i'll auger the holes oversize, for what you are using i'd use a 12" auger. this allows you a bit of room to position the post in case your hole is not exact plus gives you room to ram the thing.

a quick cleanout with a post hole shovel, line your post up, put a BIT of dirt back in and ram it with the crowbar, check your post for line then probably 2/3 of the remianing dirt in, ram again then the rest of the dirt and a few taps with the crowbar.

done right you should not have any dirt left over.

it is a suprisingly quick way of placing posts.

I do not like using concrete as imho it does not hold them effectively over time. but if your clay is wet and sticky you mat not have any options.

a good way to line up your posts is to use a few sighter posts set up outside the arena - we normally use star posts like this and stand 3 or 4 in a line to use as a sighting guide. and the best way to line them up is with a pair of binoculars as it makes the posts appear to be next to each other.

place your end posts first so you do not compound your problems as you run the line. then run a string line and using a few nails get the tops of the posts all level, mark them with a crayon, a quick run round with a chainsaw to trim the height and viola - a perfect arena surround...

 

[ray66v]

I really don't like to use concrete around wood posts, exception: on the ends of a fence, or a gate. I prefer to pack a sand and stone mix around them with a spud bar.

FYI: If you do use concrete, don't run it all the way to the top, leave about 4"-6" for dirt. This will help keep the frost from heaving them out of the ground.

 

[mouse]

clay packs well and holds well, it just can be messy/troublesome to repack if its too wet.

 

[radman1]

The relatively short boom of the toolcat makes vertical drilling a bit challenging. Can someone help you with a few holes to keep the bit vertical? Have them direct you to back up or move forward as you drill. Keep watch of how much you need to move the toolcat and watch the depth of the bit. With some practice, you will probably get good at doing it yourself. Especially with that many posts. (A vertical lift skidsteer is great for drilling vertical holes quickly.)

However, a 6" auger gives you practically no room for accurate placement of a 5-6" post in a straight line. For that size of post, I will use at least a 9" auger if tamping by hand (piece of pipe), a 12" auger if using my hydralic tamper. The hydraulic tamper requires a larger hole to get the footplate around the post on all sides. Hydraulic tampers are great. You can tamp quickly if someone slowly as dirt while another guy runs the tamper.

 

[ndnewbie]

I'll have to look around for a hydralic tapper. What kind do you use? I am working in this amazing clay. Tapping it down into a decent sized hole requires something pretty heavy, and a whole lot of jamming. Its a major project on each hole, giving rise to my desire to dig the hole just right to fit the post. We dump in a bag of dry quick crete, because it will pour down a thin space. It eventually sucks up moisture and hardens. It should work for this purpose, even though I woudn't do it this way for fence corners.

You hit the nail on the head with the boom angle issue. I'll try practicing, or, if I find a tapper, we could go with bigger holes.

Thanks to all for the suggestions.

 

[MetroX]

When I set posts like this, I use a 12" auger. It helps to have someone sighting the auger from the side to tell you if you need to go forward / backwards to keep it level, I can say from experience that after you do a 100 or so holes you'll be able to tell from the cab when you are drilling straight.

For a building, I have used 12" concrete 'cookies' which I drop into the hole after cleaning out, they are just round pads of concrete about 3" thick. This gives a good footing for the post to sit on. Then drop the post on top of the cookie, align it, and then backfill with pea stone, not the dirt / clay you removed from the hole. Pea stone will allow water to drain away from the wood post, so you won't have issue with heaving in the winter. The stone will settle after a while, so you will need to top off the pea stone after a year or so. It'll cost you a little extra for materials (cookies and pea stone) but the installation will go quickly, remain stable through the seasons, and give you the option of pulling out a post and re-setting it IF you make a mistake in placing it the first time. Not that I have ever needed to do that...

When setting fence posts, you don't need the cookie, just the pea stone. I wouldn't recommend filling with dirt even for line posts. Set your corners with concrete if they will have tension on them, like high-tensile wire or no-climb horse fence. For 3 or 4 rail vinyl or wood, I set the corners the same as line posts, just pea stone. Just my experience!

 

[DEWFPO]

I use pea stone as well for filling and it works great. It lets water drain and will settle a little after the first year as Metrox has said but its fills quickly and easily and you really don't have to tamp it. If in tight clays as you are, I dig the hole a little deeper and drop pea stone in the bottom so any water that gets in the hole drains down below the bottom of the post instead of getting wicked up the post.

DEWFPO

 

[ndnewbie]

You guys are great. Its 4:00, and I just found I can still get a load delivered out yet today. Thanks much!

 

[ray66v]

I use pea stone as well for filling and it works great. It lets water drain and will settle a little after the first year as Metrox has said but its fills quickly and easily and you really don't have to tamp it. If in tight clays as you are, I dig the hole a little deeper and drop pea stone in the bottom so any water that gets in the hole drains down below the bottom of the post instead of getting wicked up the post.

DEWFPO

One problem with clay soil is, it does not drain well. Any voids will fill with water when the ground is wet. Water is going to go in. But, not out. That's why I like a sand and gravel mix. It packs tighter, leaving almost no voids, this will minimize the amount of water held in the hole.