Geotechnical Dispute 4

[genomty]

Good Afetrnoon:

The firm for I work has been requested as third party in a dispute between two other firms. As far as i know, the project involved considers a 15 story building with two basement levels. Apparently dispute started due to a complain of someone with building contractor that was not agree with the firm 1 geotechnical report, apparently (according to his or her judgment)soils described in report are different to the encountered, contractor hiere another geotechinal firm, which alleged after review the firm 1 report that report was wrong, they performed some additional borings and gave new recommendations, as result bearing capacity has been reduced and foundation cost has raised, so, they have been discussing about this issue one or two weeks. Now we are involved as referee in this dispute. We have received only the firm 1 report,based in the information we have within two block perimeter, this report does not look to be right. We are going to review report two and issue a meeting to interview both consulting firms, based in our previews expirience with firm two, it is possible that they report will be quite conservative, so, we are anticipating that we are going to drill at least a boring for verification. After all the process we are going to present our conclusions. Question here is, Is there any standard procedure or guideline to follow in order to perform this task? This is the first time that I am involved in a dispute like this,I mean, I've participated in forensic and CMT disputes, but never in a case like this, as third party. It seems to be quite interesting but one of the firms will result damaged and they would not be happy, I'll be glad to receive some advices

Thnaks in advance

 

[cvg]

you should plan on going to court or being involved in some way in the future lawsuit. Anticipate the questions the judge and attorneys will ask and make sure you cover it in your scope of work.

 

[InDepth]

You may want to define "wrong." The real question is, did the first geotechnnical engineer perform tests per industry standards and current practice in the area? If the first engineer was negligent then there is a case. If the first engineer performed tests and provided recommendations following industry standards (and latest current practice) then he is on solid ground. Now, the question about the second geotech...was he conservative and/or did he follow the same standards as engineer # 1...or did he use the latest and greatest.

You also need to compare apple to apples. Both getechs performed their own borings...so the question is did the 2nd geotech also account for the data in the first borings...or did they perform borings in the exact location as the first....potentially the soils vary across the site...not to mention discrepancies in the methods used for broing and testing. Also, compare Factories of Safety and calculation methodlogy. Is the issue strength or settlement? Are there lenses of soil or portions of the site that triggered all recommendations?

If you do the borings...remember to compare apples to apples. Also, depending on wether the project is in design or is already built changes the tactic and handling. If in design, it is up to the owner to choose which geotech report they are willing to accept and are confident in the results.

Just remember, be systematic and don't say one engineer was conservative. State your results and determine if both engineers followed standard practice. If one was clearly negligent and didn't follow industry standards then the confidence in their recommendations is reduced. Present it as "risk" to the owner.

 

[Ron]

You are essentially being asked to opine on a "Standard of Care" issue. As InDepth noted, each issued opinions based on their data set. Did they do anything wrong? Perhaps not. Keep in mind that professionals often disagree on the interpretation of the same data set. A difference of opinion is sometimes just that.

Assuming Firm 1 used a reasonable approach to gathering data based on their scope of services and gave reasonable recommendations based on the data set, then they have not violated their standard of care.

If Firm 2 did the same but reached a different conclusion, then you have to be the arbiter of whether each conclusion reached was reasonable given the available data. Perhaps the difference is just conservatism. Perhaps it's a valid difference in data, for which you'll have to take additional data to validate one or the other.

I would suggest that you develop a short checklist of a reasonable scope of services:

1. Did they do an adequate number of soil test borings and to sufficient depths?
2. Were the borings taken in areas of relevance to the proposed structure?
3. Did they perform adequate and relevant lab tests to determine soil properties?
4. Were their computations and approach consistent with the data and accepted area practice?
5. Do their conclusions match their data and computations?
6. Are their recommendations consistent with those of similar buildings in the immediate proximity?
7. Is there anything unique about this structure that requires thinking "outside the box" for the geotechnical considerations?
8. How variable are the soils across this site? Is there a lot of variability or are the soils consistent throughout their subsurface profile?
9. If Firm 1's recommendations are followed, what is the downside? Will the structure settle more? Will there be a potential bearing capacity failure?

Good luck. These are always interesting. The key for your firm is to remain objective and base your opinions on hard data and consistency with area practice. Forget the people, forget the firms. Do your evaluation as a disinterested, third party observer. Let the chips fall where they fall.

 

[BigH]

Ron gives, as is his usual practice, a good detailed assessment of how to address the issues. You have indicated that this is your first "referee" assignment. Does anyone else in your firm have the experience? Are you the lead or assisting a more senior engineer? If this is your first and your firm has no experience in this type of work - which is fraught with dangers as you have noted - I wouldn't have taken the project. Remember that, noted earlier, give the same data to 5 geotechs and you'll get 4 different sets of recommendations; and they might all be correct but with different levels of risk. In foundation design, a little conservatism is not a bad thing. Costs to remediate in ground problems is much more onerous than the little extra cost involved with a bit more conservatism.

 

[hokie66]

Ron's advice is good, but I prefer that of BigH. You will be in the position of giving a third opinion, which may not agree with either of the other two. And if in the end the building should still have problems attributed to the founding material, you will indeed be a third party, which is a legal term best avoided. Just call yourself independent.

 

[GeoPaveTraffic]

I second hokie66's advice.

 

[fattdad]

Just to echo already-offerred sentiment. Sit down and ask yourself, if this were my job from the outset, what would have been my work plan? To what extent can I (or the firm) represent experience in the "general state of practice" within this particular geographic area (I really doesn't matter what we may typically do in Virginia when evaluating a dispute in Kansas)?

Typical problems:
. Insufficient number of borings.
. Insufficient depth of borings (i.e., performing a 15-ft deep boring in an area of 10 ft cut).
. Insufficient or irrelavent lab testing.
. Vague soil descriptions (i.e., not in conformance with a quantifible soil description method)
. Zero calculations (you should request calculations, if they exist) - recommendations just based on what "feels" right.
. Putting the onus on the construction material firm to "verify" engineering recommendations (i.e., we'd like you to use 3,000 psf for foundation design to be verified using DCP during construction).
. Not having any perspective on the structural loading (i.e., if you are sizing footings based on settlement criteria and limiting bearing capactity based on the full extent of the live load, it'll be conservative before you even begin your calculation).

The first thing you have to be prepared to "defend" is what makes you the expert? If you've never had this experience before, you have quite an uphill battle!

f-d


¡papá gordo ain’t no madre flaca!

 

[InDepth]

All good points gentlemen. Standard of care.

Be Objective and use the data. Don't try and come up with your own recommendations...just make checks of what seems reasonable and understand the geotech methodolgies.

Taking a list such as Ron's, I would also be prepared to assign a level of risk to each item & the importance of each item to the final recommendations. Some data is substantially more critical than others.

From this risk data you can assign responsibility....and in the end the owner can assign/distribute the lose to the responsible party in a quantifiable manner. There was a good article in IABSE a few months back that weighted and distributed the lose to responsible parties.


I know we have been talking about geotech recommendations...but say for example the structural engineer provided loads or foundation size to the geotech that were off by 2 or 3...then the geotech recommendations would probably change as well. Thus a structural engineer may also be responsible in affecting the recommendations.

 

[msucog]

ok let's look at this another way. did the firm follow the contract they signed their clients? if one firm was allotted twice the money as the other, then i would generally expect a more thorough exploration (in theory). even given the same monies, you can come up with wildly different recommendations depending on the acceptable risks, desired direction of construction, budgets or lack thereof, politics (does one firm want to give the other a black eye or take away work), available knowledge of site conditions at the time of each exploration, etc etc.

the explorations are likely tailored to the needs of each client...so likely are not identical. also, how do you define "quite conservative"? based on or against what? and what rules are everybody playing by?

lastly, does the contractor's geotech have any business in this? the contractor signed a contract with the owner...where does the contractor's firm come in to this other than trying to substantiate their client's (the contractor) viewpoint? perhaps i overlooked a few details...

 

[oldestguy]

My question is: Who asked your firm for this service? Is it some arbitration official? Is it a building owner? The contractor?

I suspect that if you don't watch out as you start, you will then be a third engineer in a round-a-bout argument and possibly in a three way law suit.

I'd not take the job unless I was hired by one or the other of the two in the dispute.

This is one to be very careful of, being sure you are aware of all the possible legal ramifications before getting involved.

 

[ishvaaag]

... and the "statistics". A pressed (or not) contractor going for some money, an owner using technical people to fend off costs, as he likely did with the 1st geotech report, and a second geotech firm that "knows better" because is more conservative. Yet I agree entirely with BigH in this thing: if you have only some extra monies to spend in a building, spend them at its foundation; you'll have something good to start with. And this starts with a good geotechnical report. First things first.

 

[molerat2210]

This sounds a little fishy. Who cares about the contractor's geotech unless there is a changed condition outside the limitations of the Firm 1 geo report in which case Firm 2 can always invite Firm 1 to reevaluate thier recommendations. There are always changed conditions where Engineers, Contractors, Owners and Everyone need to work together to resolve the issue. In this case and without any evidence of incompetence, this is all speculative on who's design is better. There is no changed condition only differing opinions on a bearing value.

Give us more specifics! What techniques did Firm 1 use to come up with thier higher bearing value? Be careful lest you have your reputation tarnished.

Best solution:

-Confirm that Firm 1 methods agree with standard of practice.
-Build according to Firm 1 design.
-Monitor Foundation Settlement over a year.
-If settlement is excessive then you know who's butt to fry.
-If settlement not excessive then charge your fee and move on.

This way your not in the middle of a geotech squabble.

 

[apsix]

"-If settlement is excessive then you know who's butt to fry."

It's a bit late then isn't it? It doesn't sound like the best solution to me.

The contractor appears to have done the responsible thing when it appeared obvious that the soil conditions didn't match the geotech report.
The standard procedure would have been to call out Firm 1 for a reappraisal. Without knowing why that wasn't done (or if it was done) it's not possible to give much advice.

 

[Doc09]

apsix asked the obvious question. Was firm 1 called upon to comment on the difference between what they have reported and that actualy found on site? if so, what was their opinion, and if not, they should be asked to do so in writing.

Just for the record, in our reports we always include a small section at the end, "basis of recommendation", in which we clearly state that "our recommendations were based on the information collected, if ground conditions prove to be different at any location, we should be called upon to reassess our recommendations".

In good will, Firm 1 should be given the chance to reasess and correct, then if they fail, it is a different story.

 

[racookpe1978]

Lots of good, cautious, well-thought advice through all of the above: (mildly) irritating that the original poster has provided no feedback or amplifying remarks.

 

[apsix]

The OP hasn't even bothered to read our responses since June 5!

 

[racookpe1978]

"Tis OK, apsix, I'm learning from the recommendations anyway - maybe more effectively than the original poster. 8<)

 

[BigH]

racookpe1978 - you wear glasses and have a mustache?

 

[genomty]

First of all, I would like to express my deep regret about not updating the post before, I'm so sorry for those who feel that have waste time answering my post and I would never leave a post without updating. I really appreciate all the comments and advices, unfortunately I was out of town doing a job in a site far away from an internet connection.

Well some new data, after reading the firm 1 report and a preliminary report of firm 2 we found the following issues:

Firm 1 skipped some sampling depths and, according to our judgment due to this lack of sampling their report has missing information, for instance they took samples at 3 6 9 and 12 meters in some borings, and in other borings they just sample at 6 and 15 meters.

I know that someone can say that they used a different criteria and I agree with diferences in criteria when your are making your analyses, however deferences when you are sampling should not be a factor that can make a big diference between one study and other, we reviewed our own files across the area and found that we had peroformed two studies nearby the area (site is located almost in the middle of the two projects we performed let's say that sites we studied are separated about 450 meters and are about 220 meters to each side form site in dispute), according to the information of those sites, stratigraphy across the area is composed by clay, clayey gravels shaley clay clayey shale and shale, nevertheless, shaley materials have a weathering degree that goes form severe to moderately weathered, and our information indicates that these materials are interbedded. So, it is common that you are drilling a sligtly weathered shale and suddenly you find a highly weathered or a dicomposed starta, trying to identify these changes during drilling without sampling is a hard task even for the most experieced drillers, in my opinion it was one of the assumpitions that firm 1 made during drilling and sampling, I mean, they found a layer of shale hard to drill (they use a small drill rig, by the pictures I would said that it has the size of a Mobile drill B 3300) and assumed that they were drilling the same material.

The above information was confirmed by preliminary report of firm 2, they sampled @ 1 meter and they found these interbedded layers. Bearing capacity of firm 1 was something like 16.5 ksf and Preliminary report of firm 2 indicated something around 5.1 ksf. Unfortunately we were not able to comply our services in this project. Our proposal was accepted, nevertheless the owner payment conditions were not acceptable to our firm, the agrement of services they sent us said something like, No payment in advace was going to be made, and they can held they payment of services as long as they considers necesary, they clarify this clause saying until they were satisfied with our conclusions, so, they might never be satisfied with our conclusions due that our conclusions probably will be in a middle point between firm 1 and firm 2, it is just an assumption based in the information we have of surrounding area. It also could mean that this dispute could go to court and by signing the agreement will not going to be paid until the court make its final decision, so we decided not to work under these conditions.