Retaining Wall Failure.
Retaining Wall Failure.
(OP)
This story is getting a lot of attention here in San Antonio.
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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RE: Retaining Wall Failure.
I have mentioned it before on this site, and I mention it to anyone who will listen - I don't believe that "industry standards" amount to much. Each element should be designed with its own criteria, loading, and conditions. It should not be acceptable to design a wall in Development B the same as a wall in Development A simply because the wall at Development A is "ok". The soil likely has different properties, capacities, moisture conditions, etc. This is true not only for retaining walls, but virtually all structures and elements within those structures.
You can bet that if this were a medical emergency, dr's would be all over every news station, and making the rounds to daytime talk shows to remind everyone how important their profession is and why only doctors can help with the problem (see all of the dr appearances when the H1N1 scare was big).
What we need is a loud voice in the (structural) engineering community doing the same for us. That would give us greater recognition, quite possibly increase our fee structure, and certainly lead to fewer failures like this.
The fact that news outlets are reporting the "industry standards" thing almost implies that it was accepted by an engineer, but they just didn't get a permit. It needs to be made clear whether-or-not this wall was designed by an engineer, and if it was whether-or-not the construction was as designed (and satisfactory).
I would love nothing more than to turn on my tv tomorrow morning and see our NCSEA president discussing the issues of this failure with someone on Good Morning America.
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
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RE: Retaining Wall Failure.
thread158-263647: slope failure endangers homes in San Antonio Texas subdivision
RE: Retaining Wall Failure.
Never, but never question engineer's judgment
RE: Retaining Wall Failure.
We have a retaining wall project that's being bid now - replacement of a 300' dry rubble wall, up to 30' high with a modular wall. The client's generic spec is based on industry standards since the contractor will select the particular wall system. HOWEVER, we did a subsurface investigation, developed design criteria, and we'll review and approve the design.
Unfortunately, many home builders (at least in northeastern Pennsylvania) are notorious for cutting corners.
As an aside: from the photos it's hard to tell what type of wall it is. It doesn't look like a modular wall or a reinforced earth type. Maybe it's a Home Depot special?
To me it looks like they might have shotcreted the slope and laid stones.
RE: Retaining Wall Failure.
I think that's a good starting point, but not sufficient for a final design (or to be built with). With all the safety factors we use it likely works, but is still not a good idea.
Just imagine how under-designed a wall has to be to fail like this. With phi factors, load factors, soil cohesion that is never accounted for, etc. it had to be woefully under-"designed".
RE: Retaining Wall Failure.
In a court of law, "industry standard" would generally mean:
The Design Code that an engineer would be expected to follow in a particular instance, such as AASHTO, IBC, ACI, etc. For example, you wouldn't expect someone to use AISC Steel Construction Manual to design this wall.
In the absence of a code, a court would look to see what is the accepted standard practice in the area.
An industry practice is more of a "means and methods"; for example on the east coast steel fabricators design connections; in the west the EOR does it. It's things like that.
RE: Retaining Wall Failure.
This wall appears to be constructed without rebar, and is quite likely "engineered" by the guy on top of the scaffold yelling down, "I need a big flat one, about a foot tall, with an angled right side! And the response being: "Hey got just the one, lemme knock off the bump on top, I'll send it right up!
Most of my experience with this is in west Texas, but I can almost see bridgebuster's second spot-on observation going into action; a new project for "After-The-Fact-Design Incorporated.
This is going to cost somebody big bucks, and ten years down the road, if the lawyers don't get it all, maybe the homeowners might even get some relief.
RE: Retaining Wall Failure.
Follow the money.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Retaining Wall Failure.
When I first read the story on yahoo, if I remember correctly, the wall did not have the necessary permit. Now I wonder, how did such a wall be completely built without the permit? I believe the project was been constructed in phases so I would imagine the city inspectors had to be going in and out in the area. And the walls are not your short 3 or 4 ft tall walls, they are alot taller; so shouldn't they have across city staff at some point? At least if I was a plan checker I would have wanted to see each wall engineered for its location.
Here in the San Francisco Bay Area, the current story involves apartment buildings in danger of collapse due to erosion of the cliff fronting the ocean. In this case, mother nature is the driving force but I have been following the story in different networks, and the way that engineered aspects are reported are not necessarily in the fairest possible way to the non-engineering public. Here is a link to this story.
http://www.ktvu.com/news/22324572/detail.html
(by the way the link above is for info only, I don't mean to list KTVU as an example of bad reporting or blaming it for the bad reporting practices of others)
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
I would guess that in this case whomever put up the wall couldn't tell you the difference between those two items.
EEJaime
RE: Retaining Wall Failure.
My work does not involve residential construction, so I don't know how much inspection is actually done by city authorities. But I have a feeling that not every house in a large development is inspected. These developments and houses are built so rapidly that there's no possible way every one gets inspected as it should.
RE: Retaining Wall Failure.
That's kind of the way things were in southeastern Queens (NYC)for many years. Contractor's did a nice job of putting in catch basins but they forgot to put in MOST of the sewer pipes.
"How was the wall constructed without the city knowing?"
If it's like NYC, there probably isn't one person repsonsible for inspecting everything. Here, the Building Department has numerous groups with a specific inspection function - electrical; plumbing; elevators; cranes; etc. Human nature -wall? not my job.
One thing though in NYC, all of the permits for a building project - and there are many - have to be conspicuously posted at the site for the general public. Builders are usually good about this in order to avoid paying fines. The city is very good about issuing violations because it makes a lot of money from fines.
RE: Retaining Wall Failure.
The gist of the letter was that any fatality as a result of construction should immediately open a file for investigation/review. The main purpose of professional associations is to safeguard the public. I heard nothing...
Dik
RE: Retaining Wall Failure.
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__________
"In regards to the retaining wall, there were some reports that we previously repaired the retaining wall. Centex did fully rebuild this retaining wall in early 2007 following indications that the wall was not performing to expectations. The decision was made to completely rebuild the wall and substantially reinforce its foundation."
Get the latest crime reports in your neighborhood with the Statesman's Crime Tracker.
__________
(I don't think they actually meant to make the crime reports part of this story.)
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
What human nature sometimes forgets is that directly or indirectly everyone's paycheck (whether you are the city inspector, the contractor, the engigeer or other consultant) comes from the same place; the home owner or whoever the client will be for your project. By no means do I aim to shift attention or blame away from whoever was responsible (there is such a concept as taking responsibility for your actions) for this but we call all help each other a little more if we would stop saying, "not my job". I think in the end it makes us better engineers.
CTW,
Most of my work has been in residential development. In some cases and depending on the sequence of construction such tall retaining walls would fall under either the "mass grading permit" or "grading permit" for that phase of the project.
RE: Retaining Wall Failure.
The problem in residential construction is the lack of knowlege about fundamentals.
Two of the most common mistakes I've seen in residential construction are 1) 10' tall retaining walls with a 2' wide footing and 2) gable walls that neither have bracing at the ceiling level or are connected adequately at the top to the roof deck.
There's nothing wrong with being ignorant. It simply mean you just don't know and need to be taught. I'm ignorant about a lot of things that aren't structural enginering. But what you don't know CAN hurt you and a lot of home builders don't know the mechanincs of how a house distributes loads.
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
They cite the possibility of a faulty design here. That leaves me to assume that no Geotech report was done. But, with the 3 foot shear key being a BIG indicator of sliding problems, I would think that there was one used. Perhaps an adjoining site? I think I remember a comment to this effect.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
Dik
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
I often wonder what the liability ramifications are if I design something and it is not constructed in accordance with my design, but I am not engaged for the Construction Administration portion of services. I assume that somewhere down the road, as in this memo, which states among possible causes for failure, the "Design failure in the wall was never properly designed in the first place." [Isn't that the most atrociously written sentence?]
When this gets to court everyone ever associated with it will be named. This memo does not state why the author feels that the design was possibly at fault, but that possibility is always on the list, especially if it is designed by a P.E. with Errors and Omissions insurance.
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
The other thing about that list that bugs me is how they list "Slip failure of the soil strata below the wall" as if it would cause the problem without there having been a human failure to adequately understand and accommodate the site conditions. The foundation is what it is. Can't blame the dirt.
RE: Retaining Wall Failure.
Thank you. "Can't blame the dirt"? Lawyers can blame anything. The contractor's lawyer will probably name the earthworms in his defense for undermining the wall. And you are right, only the lawyers will make out on this one.
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
That's why I make a point for mentioning what we think are issues on retaining walls if we look at another consultants plans and don't 100% agree. I don't really care if I am doing some extra work for free, I would hate to be a homeowner with issues down the line because someone used a generic xyz design for the entire site.
That's probably why I am more curious how this wall problem ends. Let's say I know what Centex's reputation was. I was surprised to hear Pulte mentioned since they weren't exactly the developer at the time and I think they have a very different reputation.
Civil Development Group, LLC
Los Angeles Civil Engineering specializing in Hillside Grading
http://civildevelopmentgroup.com
http://civildevelopmentgroup.com/blog
RE: Retaining Wall Failure.
RE: Retaining Wall Failure.
I too have been involved in contractor/client "shotgun" lawsuits which named everybody ever even remotely associated with the project and have seen all too often our attorneys' advice to "just negotiate as small a percentage of liability as possible and get on with it". Very discouraging. Especially when we actually had ZERO liability for the issue at hand.
We've even settled a lawsuit by one particularly unscrupulous contractor and his unbelievable incompetant and totally out of touch attorneys, whom filed suit because our enforcment of the specification on a project, insisting that they provide an item specified or an equal product was "restraint of trade". One of the most ludicrous arguments I've ever seen. After 4 months of depositions in which I sat and answered the same questions at least twenty times each, our attorney told us we would win at trial, but it would cost us more than the settlement they were asking. Absolutely absurd.
The construction industry has gone to the dogs in the last 25 years, well some portions of it. We still occasionally are involved with professional contractors and quality tradesmen and ethical ownership. They seem fewer and farther between each year.
Regards,
EEJaime
RE: Retaining Wall Failure.
Of course the attorneys will name everyone in sight if they know the other attorney is going to tell them to settle. It's easy money for the attorneys (all of them).
If I ever found myself in that situation, I would definitely fight it (if I were not at fault). I think that would help draw a line about what and who should be sued. I'm not saying my one stand would change anything, but I would certainly sleep better at night.
What is cheaper in the long run? Settling 20 suits when you weren't wrong, or defending 3 or 4? Isn't there some provision that would allow us to collect attorneys' fees if we are named in a suit that is "frivolous"?
RE: Retaining Wall Failure.
I totally agree, and if I were an independant engineer in the suit I would have done as you suggest if finances allowed. However, I was working with a mult-office, multi-state, corporate minded company that was basically run by lawyers anyway. A no-win situation for us defending a technically 'pure' stance. Bean counters will out.
EEJaime
RE: Retaining Wall Failure.
Second, it's a small engineering world. You might need or want to do business with the same people that are suing you some time. Permanently pissing them off might be poor business in the future.
I was advised by an owner of our company that it's never worth going to trial. Even when you win, you lose.
RE: Retaining Wall Failure.
Is it really poor business to piss them off if they're costing you money when you're not at fault? I know I sound like I'm on a soapbox, but some things just really aren't right!
RE: Retaining Wall Failure.
We were sued along with the contractor. Why? Our name was on the plans, even though the attorneys knew we weren't involved. Then again, if lawyer-logic there was the remote possibility that it was our fault the forms were set wrong. Initially, the lawsuit didn't include the CI firm. Anyway, we were eventually released from the suit but it cost us $75 grand - insurance deductible. It was a lot of money for us - we were a small firm at the time.
In the second case, we prepared plans for a bridge deck rehab - new overlay. The bridge has three lanes in each direction (east and west). In the mornings, the left lane of the east bound side is used as a bus lane. There's an opening in the concrete median and PLENTY of signs that say "BUSES and TAXIS ONLY". The bus lane is delineated with cones every 10'. One morning, a motorist went in the bus lane, then he went into the center lane - head-on collision; killed instantly. Again, our name was on the plans. I don't recall how much it cost us to get out of the suit.
RE: Retaining Wall Failure.
I know times are tough but that's ridiculous. It would only be poor business if you chose to do business with someone who previously sued you.
RE: Retaining Wall Failure.
Dik
RE: Retaining Wall Failure.
You don't have to believe me, but you're going to run into the same people after the litigation is over. You can settle or fight to the death. Is that where you want to spend your energy?
RE: Retaining Wall Failure.
Of course, it's a lousy way to do business.