Discobedience
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Joined: Tue May 23, 2017 9:46 pm

Building Tiered Garden Box on Sloped Hill - Need Advice

I am going to be building a 2 tiered planter wall into a sloping hill.

My backyard slopes down into my driveway. Typically wet in spring, always bringing dirt with it.

I'd like to build that wall into the sloped hill.

Dimensions:

24' in length
60" depth
29" height

I'm planning to possibly use 3, 8ft railroad ties laid lengthwise to 24ft. Stacked to 29 inches in height.

Do I need to do anything special to prep the hill or plan for run off for wet season?

Can I just dig into the hill and lie railroad ties leaving soil where I want to lay the ties?

How do I "anchor" the wall?

Any advice or helpful suggestions?

Thanks

imafan26
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Posts: 13961
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

It sounds like you are building a retaining wall. I think most places don't require permits if the wall is under 4 ft, but you would have to check with your local laws on that one.
It would be better to have some drainage to make sure the walls can handle the weight. It would help since you know you have issues with rain to put a French drain in behind the wall to direct water away. My wall is CMU and it is not a retaining wall but we still anchored it with rebar every 24 inches and we dry laid the tile so the water could weep between the tiles. We filled the cores with rocks and dirt. We used some of the cores to plant herbs but the wall was too hot for most plants so we capped them and hung deck boxes over them instead.

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tomf
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Joined: Mon May 18, 2009 8:15 am
Location: Oregon

imafan26 has good advice, the french drain may be the way to go if you can put it in and find a place for the water to go. I think a photo would be nice so we could see what you need to do. 3 rail road ties? they are about 8 to 9 foot and about 8" high so it would take a lot more than that. You would need to stack 3 or 4 ties high, a stack that tall would need some kind of dead men to hold it, especially if the soil slides when wet. You may look into stone as well, cost more but lasts for ever and looks good.

Lillian Dillard
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Joined: Thu Jun 29, 2017 7:29 am

The sole purpose of creating a retaining wall is to hold back the soil. But it can be effectively used to create exceptionally good outdoor spaces. Since you are planning to build it on a slope smooth it out first in case of an uneven slope which can provide it with a better stability. ground anchoring is the best design solution for retaining walls as they meet with post-earthquake design codes. You can refer this https://www.icc-es.org/Reports/pdf_files/ESR-1959.pdf for ground anchoring guidelines.



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