Retaining Wall Questions 6

[elfman]

I am trained as a mechanical engineer and as such am feeling moderately dumb when it comes to soil retention. I have a shared property line that is a slope and needs to be retained. There is also a pretty good possibility of having a fair amount of drainage along the top as well as the bottom of what will be the wall. The soil is, as far as I can tell from what I have read, heavy clay with a fair amount of rocks and gravel. The slope on one end is about 3 to 4 feet high, at the other end, 6 feet high. It is about 70-80 feet long. At the base at the shallow end, there is a storm drain.

It has been suggested that a rock/boulder gravity wall is the cheapest, which I can’t verify at this time, but someone else will do the work. I am very concerned about erosion behind the wall and along the base. What can be done in such a situation to keep the soil where it is and have a good, stable, long-lasting wall?

What are some of my other options in building the retaining wall? I am trying to keep the budget as low as possible.

Finally, having a good knowledge of mechanical engineering, is there a source where can I get some good practical learning on the design of retaining wall systems and earth retention and the necessary governing equations? Thanks in advance for the help!!

 

[cdh61]

elfman,

Do a review of the information on the topic of retaining walls in the form. Lots of references given.

A design of a retaining wall should be completed by a person who practices in this field. Best to contact a local who can aid you in the design and provide advice as required. This may or may not include the placement of geofabrics between the rock and clay soils. There are several factors which will need to be addressed before finalization of the wall type (rock, gabion baskets, concrete, soil reinforcement). The wall is not that high, but there are the other factors such as water level, slope angle, property line/storm drain details will all have to be worked out.

regards

 

[boo1]

In most states, retaining wall designs taller than about 4 feet must be designed by or approved by a qualified, licensed professional engineer. Additionally, it is important to check with and adhere to local building codes prior to any construction, even when walls are shorter than four feet. Retaining walls are, and should always be viewed as load bearing members first, and aesthetic groundscapes second.

 

[layfieldman]

As opposed to building a retaining wall you could just steepen the slope to something like 1:1 using a geogrid or geotextile. This would provide reinforcement to prevent lost of soil but requires excavation to the required embedment length. It is cheaper but you do not gain as much usable ground as with a wall.

 

[AlohaBob]

Also keep in mind safety for people walking by. You may need to build a fence to prevent someone from toppling down the wall. Or an alternate could be terracing.

There's timber retaining walls.

Masonry landscape block.

Structural concrete or masonry.

 

[wallguy]

Since no one was specifically mention segmental retaining wall blocks Elfman, I will. These are usually 8" tall by 18" wide and 12" deep. There are a number of variations on sizes. These systems usually combine a block and geosynthetic to make a soil reinforced wall. Except for wood, gabion and sometimes poured concrete, these are the less expensive options. Although you mention someone else doing the work you could install these systems and save money.

The best place to start is with your local block companies or wall installers (if you hire an installer). I can give you the name of the systems that are in you area if you would like. The local installers will also know all the local codes in the area. You might even consider some hardscaping landscape contractors.

The best place to go to learn about design and construction is probably the "systems" website.

In reverse alphabetical order:

http://www.westblocksystems.com

http://www.versa-lok.com

http://www.keystonewalls.com

http://www.anchorwall.com

These are just a few and will be good places to start if you want a decorative face. Also their websites might give locations of dealers.

Consider all the above suggestions and determine the look you want to achieve and good luck with you project.