Short retaining wall cost

[jtstruct]

We have a condition where we would like to put in approximately 30 feet (in length) of a 5 foot wide sidewalk. The slope in this condition is approximately 6 in 12, resulting in (approx) a 2.5 foot drop along the sidewalk width. I'm trying to determine the most economical way to retain this small amount of soil. We plan to put in a concrete sidewalk, but a 3' tall, cast in place retaining wall with footing seems like it may be more work (and more expense) then necessary.

Any thoughts? Thanks for your help. (Soil in this area is generally a stiff silty clay.)

 

[Focht3]

One of the modular block wall systems seems ideal for your application. Depending on the backfill you use, you might not even need any reinforcement (anchors), although I'd probably put in one level for good measure anyway.



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[layfieldman]

I agree as well, a mortorless modular block wall would be ideal. Can be placed by hand by semi-skilled workers. 3' seems to be the limit for walls that must be engineered (in my area anyway), you should at least ask the block company to do a preliminary design though. Use a good backfill with good drainage though.

 

[jheidt2543]

An alternative to think about:

You note that the drop across the walk is approximately 2.5'. The concrete walk is 4", the drainage course under the walk is usually 6", so the 2'-6" of stiff clay is now about 1'-8". I would look into trenching a 8" - 12" thick x 3' - 4' deep curb along the one side. Form and pour it integral with the walk. Rebar corner bars may be needed to tie the wall and walk together. Whether this is cheaper than the solution offered above is something you will have to check. But, this would limit the work to only having the concrete contractor on the site and one material.

I do admit that the modular block walls do look better and since this is the 90's we engineers should be concerned with aestheics too!

 

[PSlem]

Recheck the date at the top of your post.

 

[jheidt2543]

PSlem,

Sorry, I guess I used an "old" expression meaning a "sensitive and caring guy" and didn't realize we are in a new century. Maybe it was a "senior moment"?

 

[BigH]

Nostalgia?

 

[wallguy]

jtstruct

Using a 8" tall by 12" deep modular block, with 28 degree soil (assumed poor) no real load on the wall you should put one course of geogrid (2.75')on top of the second course to be safe. If the soils are better and you have good drainage away from the wall you might get away without grid. Several block systems include mine have a deeper block, 18 to 32 inches. These systems will work with no grid. Basically a true gravity wall structure.

 

[fuchsjr]

Depending on aesthetics, you could also consider some shallow gabions. Note, whatever you choose, if there is a drop off, it is going to require a safety railing on that side; impacts the clear width of the sidewalk.

 

[DRC1]

Most precast and many redi-mix companies sell concrete blocks approximately 2 ftx 3ftx 4ft which you could use to build your wall. These blocks are also known as test weights or mafia blocks and are relatively inexpensive.

 

[GeoffD]

Aesthetically and practically a timber crib wall may be a solution but may cost slightly more - as your talking of sidewalks I assume your not in UK so I'm afrad I can't help on price.

 

[Focht3]

Timber may be marginally cheaper, but their life cycle cost is MUCH higher. I don't recommend timber unless the owner insists -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[jtstruct]

Thank you all for your input. We have decided to use a modular/segmental block wall system. We plan to start construction next month.