Need Special Retaining Wall (20')

[renz4]

Has anyone had positive experience with segmented gravity walls?
How about comparitable cost to in-situ concrete?
I have a 2:1 sloping lot with dense sandstone under minimal loose natural soil (6"-1'). To develop (& live someday) I will need extensive retained earth systems. I would like to get some of the specialty gravity, and other system retaining wall vendors out to estimate a system (other that in place pcc).
I will need walls that step up the property, and go from appox 6' of retained earth to 18'+-.
If anyone knows of any reps, or potential systems, I would love to talk to them.
Lee (805) 650-7179 wk 649-5573 hm.

thanks

 

[jdmm]

Try Lock-Load.com or Keystone or Allen Block. Geogrid reinforced segmental walls are substantially more cost effective than cast in place.

 

[Focht3]

jdmm is right. But be careful of getting prices on a nebulous project...your 'descriptor' (behind your forum 'handle') indicates that you are a geotechnical engineer. Be specific when talking to the contractors.

 

[bartshippee]

I've had excellent experiences doing segmental retaining wall design. In fact, that's what I do! You need more information before you proceed.

Simple gravity wall systems (stack-'em-up blocks) almost never can go to the height you are talking about without additional reinforcement.

The most cost effective solution MAY be a geogrid reinforced SRW, but you have to find out what's behind the wall. The support for a geogrid-reinforced wall comes from reinforcing the soil mass behind the wall. It first must be excavated out and then is put back, with reinforcement, under engineered control (using standard earthwork compaction measures). For the amount of space behind the wall, figure on needing a minimum of 60% of the height (for 20 feet, you will need at least a 12' cut behind the face of wall). This probably means a good amount of "lost" space between the wall and the property line.

Other factors to consider are the ability of the material behind the wall to be excavated, assuming it's a cut condition. If it's a fill condition, you need to understand the soil strength properties of the material to be used (will it be imported to the site?). These systems only work if one understands the soil strength properties of the reinforced, retained, and foundation soil AND designs adequate drainage provisions for the wall.

You may have significant rock issues (blasting, ripping, hammering, etc.) to contend with. Also, there may be an anchored wall alternative, such as Anchor Retaining Wall's Landmark system that might be of use, but installation is substantially more costly than a typical SRW installation.

Lastly, I don't want to quote installed SRW costs off the top of my head and beware of anyone who does. Your situation is not typical and pricing will not be, either. Many sales reps will give you a "ballpark" that may be no where near your actual cost. In any event, rest assured. SRW's of up to 50' and higher are out there, performing beautifully.

 

[clayR]

Perhaps some subsurface information would be nice to have before proceeding too far? Do I understand correctly that the wall will not extend above existing grade, and will require excavation of 1'+/- of soil and 19' of dense sandstone?

If this is the case you may want to consult with an expert to determine the stability of the rock mass.

Also, until you have a good understanding of what you have, keep all your options open. An MSE wall may or may not be the best fit here. cr