Simple terracing in 1 ft steps, what material?

I have to deal with a hillside that has a 2:3 slope (if I'm saying that right, slope goes down a two feet for every three out). The main goal here is to forestall erosion, secondary to help plantings take root. Hillside is about 70' wide, and it drops 10'. It has a mild contour to it, so straight terracing wouldn't be ideal. Anyone have ideas re a good material for the 'retaining walls'. I'm not really aiming at a full strength retaining wall system which would probably cost a fortune to install. More hoping that some easy going terracing will do enough. Like, steel pegs knocked in two feet deep, with 1 foot up, and some barrier material as the wall...what that would be I don't know, but have wondered if there is some recycled plastic 3/4" x 1' king sized benderboard material out there. Or are there 'systems' for this type of situation? I'm not eager to use the cement blocks that are common, too much weight to haul, it'd be a lot of block. There is no snow or freezing where I live.
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I don't know what your soil conditions are, but we have several slopes like that around our place. I just covered them with bark dust and let the natural vegetation grow. Digging in little terraces, planting trees, and placing boulders here and there could help naturalize and stabilize the hillside as well.
Many years ago, we terraced a hillside at our old apartment using railroad ties. The cost wasn't too bad, and they worked rather well. But, ties seem to be harder to find now than they were 20 years ago. You could do the same thing with pressure treated 6x6 timbers, but the cost would be higher.
The cement blocks designed for wall building seem to be very popular, sturdy, and easy to install. Most home centers will deliver to your site (for a fee), so hauling them shouldn't be too much of an issue. Assuming, of course, the truck can get to your site.
Take care,
Anthony
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snipped-for-privacy@unknown.com says...

Thanks for that input. We're on a regular street but it'd be a lot of hauling to get block back there...it's a lot of block. But maybe that's the way to go. The hill was grassy till last year when a gopher colony took root, and they've been accelerating the 'slide' of the hill. I wiped them out last year but they've returned. So looking for a way to mitigate the effects of the loose dirt the push out.
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We just installed a concrete paver patio. When Lowes delivered our pavers, they had an all-terrain looking forklift. They set the pallets of pavers right next to where we were working.
Assuming you have enough width for the forklift, and there aren't any major obstacles, they could probably deliver the stones right next to your hill. Worth checking with them if you want to go that route.

Hmm... I wonder if the gophers would cause problems with a terraced hillside as well? I would think they would push dirt right over the terrace onto the next level? Getting rid of the gophers sounds like a bigger problem... :)

Cover the hillside in rocks too big for them to push up, or encapsulate the whole hillside with concrete? :)
Anthony
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wheel wrote:

I would definitely opt for wood here. Where I live (Belgium), it is common practice to use flexible azobe strips (1/4" or 1/2" x 4") and matching poles (1x1" up to 2x3" depending on length) for retaining walls. You can also get panels from woven strips. Azobe is strong, has a natural look and it lasts a life time (unlike your steel bars).
Koen
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snipped-for-privacy@yahoo.com says...

That sounds like good wood, but here in California I don't think it's available. 4" tall strips and that thin would be hard to make work in a 1' tall wall though? We have redwood of course but quite expensive these days, and the 2" thickness that I'd probably need to use might not curve along the hillside contours very well.
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wheel wrote:

You would be surprised of this. I've seen 1/4" thick strips been used for retaining walls or even river banks up to 3' high. Supporting poles are typically placed 20" apart.

It's also known as Ekki or Bongossi so you may want to check with a local supplier specialized in hardwood or wood for garden use. Here's a link (with extra info on the wood's qualities) for a Canadian supplier: http://www3.sympatico.ca/tmt/index.htm (I guess you should be able to get it in the US too.)
I find it reasonably cheap at US$ 10 for a 1' x 10' panel at my local supplier.
Greetings,
Koen
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I wonder if those synthetic deck boards would work? They're more flexible than wood, and aren't supposed to rot.
Anthony
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I'd expect them to slowly bow out further as long as the dirt was pushing on them.
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wheel wrote:

Is that the entire slope, or just the portion on your property? ie, are you on the top or bottom of a mountain?

That is a pretty large piece of ground to rearrange. Is there erosion now? Gullies? What is at bottom of slope? Where is your house in relation to the slope? Soil type? Trees? Native plants? If you are just dealing with a graded part of a building lot with a few bare spots, I'd fill in the washed out soil first. Plant something with good root system. Laying down a little flagstone with landscape cloth behind it would help keep soil in place til plants fill in. I would consider taking some photos to county ag extension service - they should be able to offer advice (free) and give tips on what to plant that doesn't require high maintenance.
If I understand the message right, the area in question is about 15x70. New plants with shredded cypress mulch can hold soil just fine. Mondo grass is one plant that is great for Florida, but we don't have hillsides to worry about. it is a plant that is attractive, doesn't require any particular care, and won't take over the landscape. A plant like that, across a slope, would do a lot to slow runoff and erosion.
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reslope a little so its closer to the angle of natural repose. avid building walls etc they always eventually fail.
with the right planting you will ave success,
stuff like ivy, crownvetch, look along local highway slopes, note road dept avoids building walls since they become maintence issue.
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Yes that's the entire slope. Our property (1/2 acre) was graded 50 years ago so that part of the slope became flat and downhill form that became steeper than the natural hillside...so the slope does continue at the bottom of my problem area, but that continuing slope is 'safe'. This is Califorina, the soil is clayish I believe. House is above the slope, but the flattened area is a good 20' wide, here is no immdeidate danger of it being involved in the 'overslope' erosion...but I don't want to lose the hillside at all if possible.
There are no gullies etc. The hill was grassy (with a few bushes) till last year when a gopher colony took root, and they've been accelerating the 'slide' of the hill. I wiped them out last year but they've returned. So looking for a way to mitigate the effects of the loose dirt they push out. They put out so much dirt last summer than this year the grass didn't return with the winter rains as it usually does...so all summer the slope was mostly just exposed dirt. The new gophers are less numerous but it seems to be shaping up into a continuous battle, they're not easy to get.
I'm not sure if there are any ag stations around here, the is the east bay part of the SF Bay Area. I may have to resort to some professional type, though some I've talked to seem fairly clueless. It's not quite the situation for a real retaining wall but that's the "regular" thing to do...so I hear that.
Re plantings, I know that would help. But in my case, with gophers pushing out finely granulated soil, I think I need something like this terracing idea to keep the soil from sliding down the hill...it's just at the slope where gravity takes over.
snipped-for-privacy@earthlink.net says...

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50 year old slope sounds $Approximately$ stable, especially with the 20' buffer below. i think you could do this with plantings. i approx agree with norminn and hallerb (person who replied in parallel reply), most of the others...
find a plant oriented reveg/erosion company that doesn't restrict themselves to only natives (an inexact term of course)
or you could hire me for a cheap list of tough plants. they won't all survive the gophers, but some of the species will annoy your gophers. you can then fill the dieoffs with the survivor species. this requires a lot less work than "construction".
i live near mt. diablo. 20 years and not counting. :-)
I will try 'pinging' recent group of your posting, because your newsgroup address looks very fake:
says...

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Mother Earth News had an article many years ago (20+) where they used tires to terrace a hillside. I ran across your question in searching for more information about how this was done. I would think that the tires would be held together (bolts possibly) and I know that they were staggered such that they had a reveal that would hold vegetation. The next row was offset (side to side) as well as back into the hill and dirt was packed into the tire/open spaces that were created by this offset. Then plants were planted in the open spaces. Looked much like a pattern of window boxes or planters going up the hill. The tires would hold heat in the spring, which may be helpful but would do the same in the summer and may cause problems with tender plants. Dont know how your gophers would react to this method. I believe that there are plants that they do not like and will avoid. As one person said, check with your county extension agent. Also seeing that you live in CA it may be a problem dealing with your neighbors when you mention tires and landscaping. I am still looking for more information on terracing with tires and will forward any good information I find.
Alan
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We live in the west of england and part of our back garden is a 100 year disused sandstone quarry, surrounded by mature woodland, at the foot of large hill with a similar angled unstable slope to yours. Elms had grown abundantly to about 20' and succumbed to the Dutch disease. We cut them down, removed the diseased tops and branches and burnt them. Then we laid the trunks horizontally behind conveniently placed 2' high stumps, occasionally driving in stakes, so that a flowing flattish spiral (can you picture that?) terrace follows the line of existing rock outcrops up to a top outlook. We then backfilled with loose surface rocks and topped off with the leaf mulch and black topsoil. Planting is traditional with some water features being introduced. We dont expect either the stumps or trunks to last forever, but hope (!) that when they decay, the landscape will have compressed and stabilised with the help of the new root systems and be self supporting. Watch this space for the next 50 years. One thing we would ask, think hard before using man made materials unless absolutely unavoidable. It might sound a bit hippy, but theres enough concrete and plastic out there in the modern world, without having it all around you in your private haven.
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I just re read our message and it appears that the elms had grown to 20 inches and the stumps were 2 inches high. This, of couse, should read feet, although Im sure it was invaluable advice for any unstable bonsai gardeners.
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