earth bag retaining wall

so I'm putting up an earth-sheltered structure. nothing too serious. just a small-ish greenhouse sunk a couple of feet into the ground. I've been struggling to think of a reliable way to hold the walls up.

I considered rammed earth, but I'm in a flood plain and the dirt is roughly all sand with a bit of silt. finding clay would require an excavation on someone else's property and transporting it.

I considered posts and planks, but those aren't terribly easy to come by around here, either. we're definitely in timber country, but it seems too many folks have gotten wise to the easy sources of cheap/free lumber. our own trees are more valuable for food at the moment than as building material. maybe I just don't know where to look, but there's also the issue of wood rotting rather quickly in contact with the generally damp ground.

then I thought about gabions. rocks and welded wire would both have to be purchased, and the budget for this project is limited. the wire would rust at some point, though probably thirty or more years down the road. I'm hoping the greenhouse has a functional life longer than that.

then I thought about sandbags. plenty of folks build with sandbag walls. not exactly an aesthetic I'm a fan of, but it works. a four-foot retaining wall would take a lot of sandbags, though. I assume it would have to be a lot wider at the bottom than at the top. and I'm not sure even then that it would hold back our sandy dirt. just not something I'm real familiar with. I also don't know how much sandbags cost.

and finally, the plan that currently seems most promising to me: polypropylene super sacks. also called flexible intermediate bulk containers, or FIBCs. they're basically oversized feed bags, but get used for moving all sorts of material around. frequently rated at carrying 2500 lbs., and they'll fit a yard or more of material. so I'm thinking I could set them side-by-side for the walls. I'll just fill them up with the same dirt I dig out. anywhere from $4-$15 each from what I've seen. wouldn't take too many.

so what's wrong with this plan? terrible idea? great idea? anybody tried it before? better ideas? we've still got quite a bit of excavation to finish before we're ready for this step, but I would like to start lining materials up soon for whatever we end up doing.

What about urbanite ( re purposed scrap concrete) old sidewalks are ideal. This stuff is freely available. You might have to pay for trucking. Any contractor who works with concrete or who paves with bricks is likely to need to dump concrete slabs.

It can be laid up dry or mortared. I've been paid to haul away plenty of this stuff. With proper planing, the foundation could pay you.

urbanite is certainly not out of the question. I'm really not interested in mortaring anything for this project. partly because I want to be able to expand the greenhouse down the road. partly because I'm just not that fond of mortaring.

so, if I'm stacking it dry, how thick would an urbanite wall have to be to hold back four feet of sandy dirt? thicker at the bottom, yes?

and would you recommend just calling up local concrete contractors to ask about it? I've got a pick-em-up truck to move stuff around, but I suspect it would take quite a few loads. and I'm not at all interested in dealing with re-bar. is that usually an issue?


and what about the super sacks?

If you go for old sidewalks you can avoid re-bar. It will take more loads than you think. Concrete is about 150 lb. per cubic ft. One running ft at 4 ft high and 2 ft thick is going to weigh 1200 lb. Have a dump truck bring it. If you can lean it into the slope, the wall can be thinner. Buttressed, it can be thinner. I would go 18 inches on the base tapering to 8 or 10 at the top. Basing this on a rock retaining wall that has stood for 14 years. Check with someone in your area who builds retaining walls.

I have no opinion on the sacks having never seen them.

A rip-rap retaining wall set at the angel of repose could work nicely. A wide bench could surround your peremiter so that the sloped area is covered. Less under-bench storage but also far less retaining materials with less digging.

The distance of run on sloped rip rap may not allow you enough foot room or it may require a bench that is too wide to service properly. The solution would be to build a retaining wall under the bench as shown in this professional looking drawing. Now the wall can be much shorter and thinner.

I stumbled across this and we can help you with your Super Sack needs. You can buy those bags online and here is a link to a clearance bulk bag that I think will fit your needs:

http://www.bagcorpstore.com/35-x-35-x-46-Coated-Spout-Top-Spout-Bottom-br-Super-Sack-Bulk-Bag_p_146.html

John Salamone wrote:I stumbled across this and we can help you with your Super Sack needs. You can buy those bags online and here is a link to a clearance bulk bag that I think will fit your needs:

http://www.bagcorpstore.com/35-x-35-x-46-Coated-Spout-Top-Spout-Bottom-br-Super-Sack-Bulk-Bag_p_146.html

and what do you think about my plan? not what they're designed for, obviously, but do you see any problem with it?

It's a perfect idea! I have people use our bags to divert rivers so they would work just great. The only concern I have is the UV rays. If you want to move the bags after 200ish hours and they have been in the sun they may fail. But if you just plan on keeping them there then you should be great!

John Salamone wrote:It's a perfect idea! I have people use our bags to divert rivers so they would work just great. The only concern I have is the UV rays. If you want to move the bags after 200ish hours and they have been in the sun they may fail. But if you just plan on keeping them there then you should be great!

lovely. I planned to give them some sort of plaster coating anyhow, which I think should help out with the UV. and only one vertical side will be exposed, with the other three underground.

Cool! If you want to, use the coupon code SAVE5 at bagcorpstore.com and grab a few, then take some video of your finished product and I will post it here with your permission of course: http://www.youtube.com/user/BAGCorpStore/videos

John, you're blowing my mind. thanks. it'll be a while before I'll be able to show off the finished project, but I don't think there should be any problem with posting it on your channel.

Hi Tel,

http://earthbagbuilding.com/projects/misc.htm

These earth-filled bag project may be inspirational for your creative juices on your own project. If you'd like to see the power of earth-filled bags as a planter on the edge of a lake, take a look at Sierra's Raised Planter.

Some people just sewed together some bed sheets to make their longer tube shape for their garden beds.

Pretty cool projects abound everywhere. I hope your project is fun for you.


Max

got excited and started an order on some super sacks today and WOW is shipping and handling high. $100 for a $90 order. that slowed me down.

I checked out the bags. I assume you're filling them with dirt. If too identical twins were building a wall , one shoveling those bags full and one dry stacking urbanite, my money would be on the dry stacker finishing first. This assumes that a big stack of the stuff is on site, which is a bit of an assumtion, I know. I'm sure the bags will work. In fact they are probably far more than is required to hold back your dirt. I like to avoid driving tacks with a sledge hammer.

Dale Hodgins wrote: I checked out the bags. I assume you're filling them with dirt. If too identical twins were building a wall , one shoveling those bags full and one dry stacking urbanite, my money would be on the dry stacker finishing first. This assumes that a big stack of the stuff is on site, which is a bit of an assumtion, I know. I'm sure the bags will work. In fact they are probably far more than is required to hold back your dirt. I like to avoid driving tacks with a sledge hammer.

I certainly hear where you're coming from, Dale, and I agree. I'm also not generally a fan of bringing more plastic here if I can avoid it. but getting a dump truck on the property would be a serious undertaking. the access is closely flanked by fruit trees. there's enough space for UPS and tree service trucks, but only barely. and supposing a dump truck made it in, turning it around would be well-nigh impossible.

like you said, using our own truck to move enough urbanite would be a pretty serious hassle. I'm still not totally decided.

I hit edit but here it is as a separate posting.

Dale Hodgins wrote:I've made another professional grade drawing.

This one illustrates the space used by each system as seen inside a greenhouse 10 ft wide with walls 6 ft high and 8 ft at the peak. Notice that with the urbanite we can easily alter the width of the walkway. The height of the bench can also be adjusted at will.

At 4 ft high with the bags, with the thickness of the bench and drainage space, the soil in the grow bed would be 5 ft from the floor.

Drippings from the bench can flow to the fill below in the bottom drawing since there is an air space. With the bags,in the upper drawing, some other method of drainage must be arranged.

your drawing isn't showing up yet, but I'm curious.

from your description, though, I'm not sure we're quite on the same page. not surprising, since I've been pretty mum on details so far. if I go the super sack route, they will be outside the footprint of the greenhouse, not inside it. tables, if any, will be only on the north side of the greenhouse, which will only be around two feet below grade. and I'm building it out of 16-foot diameter hoops that I salvaged from a defunct nursery. starting with six hoops, hoping to expand later.

Well that changes things.

ah. there it is. you should have been a draftsman, Dale.

you remind me of one issue that I am concerned about with the super sacks. I've got plans to put a pond to the south of the greenhouse for aquatic plants and add solar gain during winter. the super sacks would require it to be at least three feet away. three feet probably isn't going to be a problem, but it's one more consideration.

Back again ==== Check out the thread called "Thousands of Homes Built from Earth Bags Made from Re-claimed Fishing Nets --- Disaster Relief ". Then check out the posting by Abe Connally.

If your greenhouse has strong poles sunk into the ground, strong tarps re-enforced with fish nets or pig wire could hold back the soil. It's basically a one sided gabion wall but with a tarp included since your sand would flow right through a wire gabion.

This system would be dirt cheap. You could use re-cycled chain link fencing with a tarp set to the soil side. Your wire would last a long time since it's only exposed to the air and not wet soil.

This system would also require less work than any of the others we've discussed. Not as much dirt to move and all could be moved mechanically since there's no fiddle=pissing with bags.

For super long life, use galvanized wire and EPDM rubber, the same type used on green roofs. Stronger, Faster, Better, Cheaper.

alright. been casually following that thread, but didn't follow Abe's link. I'm interested.

for the posts: seems like most wood would rot in relatively short order. your climate and mine are fairly similar, Dale, and I'm going to add more constantly warm temperatures to the fairly damp existing conditions. but I've got some black locust growing that I've been grooming for just the right project, without knowing what that project is. though I'm not sure they're big enough yet. metal posts could work, but that might end up being more expensive than the super sacks.

and I'm not sure about the expense of the tarp part. Abe et alia say billboard tarps are readily available for cheap or free, but that is unconfirmed. would be nice. you mention EPDM. I'll price that in the morning. and I've got one small section of chain-link hanging around, though I'm not sure it's enough.

I'm liking this one better than the urbanite, though I'm not totally convinced yet.

Used carpet is free and it will work just as well as tarps. Used chainlink is available free all the time. Call a cedar fencing guy. People upgrade to cedar regularly. Offer to help take it down. I've given away thousands of feet of it. Steel posts are available at scrap yards but wood will last a long time on the dry side of the wall. Call a scrap guy and buy posts before they reach the yard. These guys get less than 5 cents a pound for pipe.

A layer of vapour barrier plastic against the soil would keep the carpet dry and the carpet provides the strength so the plastic doesn't burst under soil pressure. Wire stays dry on inside of it all. We're getting down to $50 or less if you get your scrounge on.

you might want to look around for a manufacturer that buys materials in the sacks. I used to work for a company that bought concrete pigments in super sacks and when they were empty they just went in the dumpster. You could have has a few every week for free along with fiber board drums for free. I used to take the drums for storing parts in the shop.
kent

turns out a buddy of mine had a bunch of super sacks just taking up space. I remembered that I had seen one on his property filled up with something, so I asked him where he got it. turns out it was filled up with more super sacks and he didn't want them. so I'm probably going that route, because it's free. I like the chain-link and liner wall idea, but I would have to spend more time, fuel, and money buying and scavenging supplies. so the free option it is. I'll post results when they happen (at least weeks, likely months from now).

I've done this. Go check out my blog and look for rapidobe. We made a retaining wall/shelf below the rapidobe wall. We used rebar for the posts, billboard tarp and cheap mesh. The mesh gives you something for a plaster. If you keep the retaining wall short, you can use small posts (1/2 rebar). Stair step the retaining walls up the slope.

Backfill with dirt and tamp as you go. Lots of fabrics could work. Call your area billboard companies.

Abe Connally wrote:I've done this. Go check out my blog and look for rapidobe. We made a retaining wall/shelf below the rapidobe wall. We used rebar for the posts, billboard tarp and cheap mesh. The mesh gives you something for a plaster. If you keep the retaining wall short, you can use small posts (1/2 rebar). Stair step the retaining walls up the slope.

Backfill with dirt and tamp as you go. Lots of fabrics could work. Call your area billboard companies.

thanks, Abe. I like the idea, but I got a bunch of super sacks for free without doing a lot of calling around and driving to collect supplies. I'll put them in place and fill them up with our sandy soil, and work out some sort of plaster for the one exposed face.

So tel how thick are you going and are you using barbed wire between runs?  

Lauren Wild wrote:So tel how thick are you going and are you using barbed wire between runs?  

I'm embarrassed to say that years later I haven't finished this project. I filled up one super sack, though. should I ever get back to it, there will only be one course of bags, so no runs to use barbed wire between.