# power pole retaining wall



## ididit (Jan 31, 2008)

Ok i need to level my back yard to make it usable. The hill drops at about 3 to 1 pitch on an angle down to the corner of property and beyond. I have designed a wall that will have to be 14' tall at the corner and run 50' each way till it runs into ground at 0' hight. I have tossed around many ideas for a year now including used tires, stacked sackrete bags, wire reinforced earth, segmental block, or just solid poured concrete. All of witch will work just either to expensive to much work or to nice for nobody but the deer to ever see. 
My newest idea is using used utility poles. I have found some for sale that are from 12 to 20 feet long 8" to 16" diameter and only $450 for a load of about 50 delieverd. I want to dig a trench 4' deep and 2' wide along the wall site. I havent figured out excactly the method for doing this but i will stand the poles (cuting to approx. length as i go) in the center of the trench and temporarly brace them up level. Then fill with crushed lime stone or pea gravel and tamp tight. Then run a band around the top or part way down with a pole running horizontal and through bolting every 6 or 8 feet. This is only to keep all poles in line and flat along back side. If neccessary i will then tie to those bolts on the inside with thick rebar or galvaized cable to anchors in the virgin ground at about a 45* angle. Every other pole will have to be flipped end for end to keep them level because of the taper and using the largest ones for the tallest section.
After putting landscape material on inside of wall to let water not dirt escape, i will start back filling using the clay from shop site above (another project) with gravel against the wall about 2' out. 
Every 6 or 8' a pole (the same poles with the bolts) will extend up another 24-30" with a pole layed horizontal and bolted on top for a railing. Fill in between with spendles or 4" mesh galv. wire panels.
How does this sound. I do believe other than the tires its the cheapest method yet.


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## Termite (Apr 13, 2008)

It will not work, at least for long. 

A 14' tall retaining wall has an incredible amount of pressure against it. Burying the poles only 4' deep in compacted earth and gravel will not ever resist the forces the retained earth excerts. Walls that tall are always made of stacked block or similar materials, and use geomesh to use the retained earth to the wall's advantage.

I'd say you need to go back to the drawing board, or consider terracing the grade into three or four different retaining walls.


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## ididit (Jan 31, 2008)

multiple short walls would be easer but i cant afford to lose any more space on this small lot. I know tall walls are built with stacked block and geo-grid but i cant afford that and i dont need it to be pretty. It seems to me that if using the back fill to hold the geo-grid that holds stacked blocks then using cables tied to anchors buried deeper than the fill has to be as strong or stonger. If a 12" thick pole is buried 4' deep and held at the top it would take a bulldozer to push the bottom out at witch the poles would break first.
I also plan on digging out level stair step tables and backfilling and compacting on that so dirt is not sliding down a hill. This way the wall can be taken away and the dirt will stay there by itself. The wall is just to stop wind and rain errosion.
Any suggestions on improving my design?
Again 14' is the max hight at the corner witch is the stongest anyway. It gets shorter from there.


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## usmcstormvet (Aug 19, 2008)

First - research, research, research.

I used railroad ties to build a retaining wall around my pool. With help from pros on the interweb, and a good plan from researching, I built my wall with proper drainage and safety in mind by using dead-men. I also used long lenths of rebar pounded through each course in lieu of spikes. Granted, my wall is only 4' at it's highest point, personally, I would not go on the cheap when safety is paramount.

A quick search of the web I found this: 

"Building a retaining can be easy enough for do-it-yourself installation, however the higher the slope the more difficult it becomes to construct. When the slope of the land becomes too high and steep, a structural engineer is required. The reason for this is that many structural factors must be taken into consideration and resolved to prevent destabilization of the wall.

So the gravity of the situation where a retaining wall is being considered is very important. The retaining wall has to be able to do the same job that the soil presently does. Therefore the type of soil behind the wall must be considered, or better yet a drainage system can be put in place. This will allow water to be released from behind the wall, and hence put less weight pressure on the wall.

A retaining wall built with construction timbers or railroad ties should be anchored to the hillside to provide resistance to the lateral forces. If the wall is not tied back into the earth, it can bow, buckle or heave and eventually collapse. Anchoring the wall is achieved by using tiebacks or dead-men. A tie back is a construction timber that is placed perpendicular to the wall. The front end is flush with the wall and is fastened to the wall itself with large spikes. The rear end is fastened to a dead-man or a small section of lumber perpendicular to the tieback and parallel to the wall itself. Because the construction timbers and railroad ties have open spaces between the members, weep holes may not be necessary."

I was extreemly weary about my short wall, I can only imagine constructing one 14' high. I'd get professional help. 

Just my opinion from a fellow DIY'er.


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## ididit (Jan 31, 2008)

Thanks for your response and concern usmcstormvet and also for your work over seas :tank::2guns:sama::saddam:
I have been researching this sense i bought the lot 3 years ago. Everything mentioned in your response i have concidered. My design does call for tiebacks using galvanized cable or thick rebar that will last decades and when i say 14' thats all everybody hears. Again the wall is 14' MAX at the 90 degree corner witch inheritly is allready stronger because the wall holds itself. I know i proly should hire an engineer although permits and engineering is not required in my area unless the prodject will exceed $50k. This will be $20k at most including the shop and landscaping. 
Any more ideas keep'm coming please.
Im still tossing the tire wall and pole idea back and forth.


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## concretemasonry (Oct 10, 2006)

Tie backs to geo-grid are not possible unless you use some system, so your choice wil be cast in place "deadmen" (Mafia blocks).

The reason that evryone looks at the 14' height is that is where the first failure will be. Once that happens, the rest of the wall may stand for a while if it is not attached to the failed portion.

Apparently, you are insistant on doing it yourself and by your method. You do not appreciate what 14' of wet, saturated soil can do. Then you have to consider the long term movement, which can be ugly.

It seems foolish to spend $20,000+ on a wall without any information on the soil or any professional assistance/advice. I am sure you can find a cheap way to build it, but has to last without moving until you can unload the home. It is unfortunate that you are in an area without any controls to to protect your neighbors and you from yourself. - Are there any buried utilities?


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## Termite (Apr 13, 2008)

All we can do is give the best possible advice, which is advice against this design. 

Please be sure to post pictures of the wall in a year or two, but don't ask what went wrong with the design!


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## ididit (Jan 31, 2008)

Yes deadmen is what i ment. Or helical anchors. I could tie one to every pole and still be cheaper than a Allen block wall or similar. There no utilities withen 100 feet of site. Just done my own irrigation system and had them all located. Only woods and no neighbors behind the wall and never will be. 20k is for the whole project- wall, shop, driveway, landscaping, etc. I should have enough backfill when shop site is dug out only need gravel for water drainage directly behind wall . Im not insistent on doing it my way. Hell im one of the most open minded people here. Im just not accepting that the high dollar way is the only way. I cannot do this project if it will go over $20k.


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## Kap (Jun 20, 2008)

Higher price vs. lower price=doing it right vs. just doing it.


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## Termite (Apr 13, 2008)

Sometimes the expensive way is in fact the only way. This isn't some 2' garden wall you're building.

You've received good advice from professionals and a knowledgeable DIYer thus far.


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## wancho (Aug 13, 2008)

One of the most important factors in building a lasting retaining wall is global stability. Using geogrids, geosynthetics and even galvanized wire provide the retained soil an extra internal stability. 
There is another method, which is starting to gain interest, GCS (geosynthetically confined soils). With this method, you build the wall in small lifts, say 8" min compacted, layer of woven geosynthetic material, then another 8" lift of compacted material, repeat until desired height. As you build the wall upwards, you stack your facing block (cinder blocks). The facing is independent of the soil behind it, because the soil is internally stable. 
Take a look at: gcswall . com I've seen their presentation, and really like their ideas. 

Wancho


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## ididit (Jan 31, 2008)

Thanks, thats interresting, i like it, havet seen that yet. Its similar to this http://www.hilfiker.com/www/index.html. Ive already called and got a quote on the material for a wire wall and it would be 8-10k not inclucing 2k for shipping. To much.


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## wancho (Aug 13, 2008)

Yes the hilfiker wire wall is expensive because they require you to use their materials (welded wire mats) for their system's design. They have a corner on the market for their system. 

With the GCS system you can use which ever material that meets the min specs. Start looking for geosynthetic materials that act as soil seperators (landscape fabrics, soil fence material, etc...) try to find out what the materials' tested strengths are. I am pretty sure you can find a woven fabric that will fit the bill, and the total material cost will be within your budget.


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## concretemasonry (Oct 10, 2006)

ididit -

The falicy of using individual anchors to individual poles is the fact you have separate units (one directional) that will be weaker at a corner, while a continuous wall around a corner with grid (not fabric)tieing the soil together with a wall that has strength in two directions.

That is why you do not see separate units on important walls. Even sheet piling takes advantage of the continuity of a wall to distribute the load uniformly. It is very easy to split open a corner since it only takes one pole to move and cause the classic "zipper" failure.

Walls 4 to 5 high do not require engineering or geo grid. After that the amount of geogrid will increase with the depth. that is if you use SRW (retaining wall) units and not "cinder block", which have no horizontal shear strength and will slide. You also should NEVER use concrete footings for SRW block since the toe of the wall is not buried very deeply because of the geo-grid.

The other problem with the poles is you have no idea of what you are trying to hold back and have no opportunity to improve it or reduce the problems and loads. Without granular material behind the wall, you have no way to remove the water in the soil, which is the real problem causing failures. If you think water can drain out between to poles, you are fooling yourself and possibly causing a wash-out, lowering the yard level IF the wall holds.

Take some pictures during construction and post them.


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## ididit (Jan 31, 2008)

hey concrete guy. Do you think i need to fill the entire area with gravel? IF you read my first post i did plan on about 2 feet thick of gravel and the depth of the wall all the way around with a landscape fabric to separate it from the soil fill. When i said tie a cable to every post i was just being exagerative. Maybe 4' at high end and go to 6 and 8 as the wall gets lower. And like i said in the first post i will have a tie beam at the top and maybe one half way down all the way around.
I think i have a good design but i do appreciate anybody pointing out any flaws and suggesting a fix rather than just saying it wont work. Thanks


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## asa (May 21, 2009)

*timber partially in the ground*

That will last several years and then be too rotten to hold itself together. Beyond that basic problem, the caisson action of the 4' buried section will not be enough to hold back the soil pressure without the tie-back, and the tie-back connection is going to require some pretty high strength. 

Have you considered a shielded slope (nice rip-rap)? you can acheive a 45 degree slope (1:1) which should get you 2/3rds of your yard back (and level). such a slope involves placing flagstones over a 45 degree slope of your native soil and chinking between the stones so that no water can wash away the soil. Putting geo-grid 6" under the face of the slope helps, and i've seen these slopes go at least 40' in height.

(sorry for the repeat post)


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## asa (May 21, 2009)

*partially burried timber*

That will last several years and then be too rotten to hold itself together. Beyond that basic problem, the caisson action of the 4' buried section will not be enough to hold back the soil pressure without the tie-back, and the tie-back connection is going to require some pretty high strength. 

Have you considered a shielded slope (nice rip-rap)? you can acheive a 45 degree slope (1:1) which should get you 2/3rds of your yard back (and level). such a slope involves placing flagstones over a 45 degree slope of your native soil and chinking between the stones so that no water can wash away the soil. Putting geo-grid 6" under the face of the slope helps, and i've seen these slopes go at least 40' in height.


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## streetrodder (Jul 5, 2015)

Wow! 6 years since the last post from "ididit" about his retaining wall project and i hope he is still in touch with this chat room, because i have almost the identical situation in my backyard and had considered all the same options and came up with the same conclusion - that power poles would be the least costly way of building the wall. I would love to get a reply on what course of action ididit took and what the outcome is today. There are a couple differences in our construction ideas: First, my back wall is 11 feet tall and 40 feet long, tapering to ground level after another 40 feet. Second, the side wall is only about 5 feet high and tapering into the ground at 60 feet. The main difference between our methods is i was planning to stack the poles horizontally with vertical poles behind as support about every 5 feet, 4 feet in the ground, set in concrete. The poles are 20 feet long and brand new, treated poles. Salesman says they are guaranteed for life against rot. Not sure about that claim but that's what he said. I'm 65 so 20 years from now, who knows. I have had experience with used RR ties that are still in place after 15 years. (now starting to show rot in a couple places but not bad) For added strength to the 11 foot pole wall, instead of geo grid woven material where they recommend #57 limestone, i was planning to use used chainlink fence with a larger limestone rock compacted below and above the fence material, sandwiched between 2 courses (lift)of poles and laid back and on top of more compacted rock and more rock on top of that. This process would be repeated every 2 or 3 courses of poles, which would be staggered like house brick and pinned with 5/8 rebar every 3 feet. The higher the wall gets, the longer the chainlink fence would extend back into the compacted backfill. Where the poles meet end to end, they would be backed by a verticle support pole. The number 1 reason for retaining wall failure is improper drainage so all precaution would be taken to prevent water retention. Everyone knows material prices have gone thru the roof - poles still seem to be the least expensive. All commits and suggestions are welcome. Would especially like to hear from ididit.


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