Aging Retaining Wall

[WebfootHomeImprovements]

Hi there! First post! I have a retaining wall that's in a remote area in Central Oregon. It stands about 10-12' high and it's bowing and leaning against trees that are in place. Above it is a gravel parking pad. It's built with larger pressure treated wood beams. I have no idea if the bowing condition is stable with the tree block or if I have a dangerous situation that needs to be remedied. Does anyone have a recommendation for a company of type of company that inspects the integrity of a retaining wall? I'm striking out. Thank you!

 

[JAE]

Call a local geotechnical engineer. A structural engineer might work as well.

 

[XR250]

No one is going to tell you the wall is OK as it is impossible to determine that.
Timber walls are typically not engineered and don't have a very long life.
Even when they are "engineered" the designs are typically pretty sketchy.

 

[jerseyshore]

No one is going to tell you the wall is OK as it is impossible to determine that.
Timber walls are typically not engineered and don't have a very long life.
Even when they are "engineered" the designs are typically pretty sketchy.

I posted about this last year and the consensus was that a regular old school RR tie wall is not engineered and never was. The best resources I've ever found were some "prescriptive" documents.

XR is right that no one is going to tell you the wall is okay.

 

[gte447f]

Well, I assess timber retaining walls all the time. I have to tell my client's something. OP, you need to hire a local structural engineer to assess the condition of the wall in person. A local engineer may very well tell you that the wall is "OK", although based on your description of "bowing and leaning against trees" as well as a vehicle/traffic surcharge on the wall, I wouldn't get my hopes up.

 

[XR250]

Well, I assess timber retaining walls all the time. I have to tell my client's something. OP, you need to hire a local structural engineer to assess the condition of the wall in person. A local engineer may very well tell you that the wall is "OK", although based on your description of "bowing and leaning against trees" as well as a vehicle/traffic surcharge on the wall, I wouldn't get my hopes up.

Even if the wall is not leaning how can you make assessments of timber or any retaining walls other than "it seems to be functioning as intended but it could start leaning tomorrow"

 

[gte447f]

Even if the wall is not leaning how can you make assessments of timber or any retaining walls other than "it seems to be functioning as intended but it could start leaning tomorrow"

It is a condition assessment, not an independent verification of an engineered design. The process and the intent is not much different whether the subject structure or structural component is a timber retaining wall, CMU retaining wall, concrete retaining wall, beam, or building. I perform structural condition assessments of multitude structural systems all the time and the vast majority do not include or require any engineering calculations in the preliminary stages. The purpose is to perform visual observations for indications of structural deficiencies.

"It seems to be functioning as intended" can be a part of a perfectly legitimate and useful set of findings in some instances. Even though possible, "it could start leaning tomorrow" is probably not a very likely, accurate, or useful finding if all other indications are that "it seems to be functioning as intended".

 

[LittleInch]

How old is it?

Any drawings?

Bowing in which direction?

Pressure tested timber is still timber and subject to rot, vermin,, creep etc so it may need to be replaced.

 

[XR250]

It is a condition assessment, not an independent verification of an engineered design. The process and the intent is not much different whether the subject structure or structural component is a timber retaining wall, CMU retaining wall, concrete retaining wall, beam, or building. I perform structural condition assessments of multitude structural systems all the time and the vast majority do not include or require any engineering calculations in the preliminary stages. The purpose is to perform visual observations for indications of structural deficiencies.

"It seems to be functioning as intended" can be a part of a perfectly legitimate and useful set of findings in some instances. Even though possible, "it could start leaning tomorrow" is probably not a very likely, accurate, or useful finding if all other indications are that "it seems to be functioning as intended".

I typically don't do structural condition assessments because the risk/reward is not there for me. The only way I would comment on a retaining wall would be "appears to be functioning as intended however, the future performance is unknown" Not a whole lot of engineering there.
In my area many retaining walls/basements are just a good hurricane rain away from failure.

 

[LittleInch]

If those trees aren't holding that wall up what is?

But agree, no one is going to say it is fine or give you any certainty that it might not collapse at the next heavy period of rain or indeed dry spell when the timer dries out.

Ita unlikely to completely collapse without warning, but how far is too far for a bulge?? No one knows.

 

[Eng16080]

It stands about 10-12' high and it's bowing and leaning against trees that are in place

I'll go out on a limb here and say the wall is probably not safe.

 

[WebfootHomeImprovements]

Call a local geotechnical engineer. A structural engineer might work as well.

Thank you!

 

[WebfootHomeImprovements]

Well, I assess timber retaining walls all the time. I have to tell my client's something. OP, you need to hire a local structural engineer to assess the condition of the wall in person. A local engineer may very well tell you that the wall is "OK", although based on your description of "bowing and leaning against trees" as well as a vehicle/traffic surcharge on the wall, I wouldn't get my hopes up.

This makes sense, thank you!

 

[WebfootHomeImprovements]

How old is it?

Any drawings?

Bowing in which direction?

Pressure tested timber is still timber and subject to rot, vermin,, creep etc so it may need to be replaced.

The age is unknown, but I'd give it 20-30 years. No drawings, likely no original "engineering" per se. This is an off grid community that's a bit remote.

It is bowing outward (towards the viewer), but not in any sort of buckling way. I'm a contractor, not engineer, but able to inspect for rot and other signs of wear, and none are present, although most would likely be hidden on the other side!

 

[WebfootHomeImprovements]

If those trees aren't holding that wall up what is?

But agree, no one is going to say it is fine or give you any certainty that it might not collapse at the next heavy period of rain or indeed dry spell when the timer dries out.

Ita unlikely to completely collapse without warning, but how far is too far for a bulge?? No one knows.

Makes sense! And I agree, I wouldn't expect a avalanche. Our area is in the high desert, hurricanes and heavy rains are uncommon

 

[JoelTXCive]

Who owns the wall? A governmental entity or private organization?

If private, then my recommendation would be to go through the steps of getting a geotech to evaluate; and then start saving money for a new wall.

The geotech report might serve to help accelerate the replacement timeline.

 

[WebfootHomeImprovements]

Who owns the wall? A governmental entity or private organization?

If private, then my recommendation would be to go through the steps of getting a geotech to evaluate; and then start saving money for a new wall.

The geotech report might serve to help accelerate the replacement timeline.

I own the wall. In the end, I agree with the group consensus that no one is going to give a 30+ year old wall the a-okay. We're going to add some sort of measuring tool so we can identify if it's slowly moving out or holding tight, then just watch that regularly. It'll be a big expensive project to rebuild, we'll start saving