Geotechnical Report and requiring construction phase services 11

BRO said:

...if there was a failure, but the geotech didn't do observations are their recommendations invalid?

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This situation probably does not occur very often. As an Owner, we retained geotech firms frequently to get their recommendations... and that's all we wanted, professional service. A proposal from a geotech firm that "insisted" on followup inspections would have had their proposal rejected as "Nonresponsive".

On the other hand, when geotech advice proved to be flawed we considered that to be routine risk with this type investigation... no legal action. However, that geotech firm would probably not get repeat business from us.

I think it's unusual to write it so bluntly; that being said, geotechnical inspections and observations are part and parcel of the business and essentially are the required standard of care (i.e. carried out independently).

Plus, there is a financial element; most of the bottom of the market is dominated by firms that essentially do reporting and design at cost or below cost in order to win follow on construction testing services where the money is made. Is that the type of company whose advice / recommendations you really want? Usually, good advice / consultants that don't require follow on services to make money is significantly more expensive.

If I prepare and sign and stamp a report for a project, my last opportunity to see if the site conditions conform with recommendations based on limited exploration, testing and analysis is during construction.

If I received a call from a client wanting me to provide construction testing and observation services for someone else's report, I'd review the existing geotechnical report and decide if I'd be able to live with it. And if not, I'd write a proposal for additional services to address either insufficient information or to clarify what was in the report. The separation of the report generator from the construction services follows government and some private practice to get some objectivity on the design report. And it's about getting another insurance contributor if there is a problem.

I've been called during construction to resolve differences in the encountered conditions versus what was anticipated based on the investigation. In some cases the conditions did differ and required additional evaluation, and in other cases, the testing personnel never looked at the geotechnical report - they were just there to test and turn in numbers to confirm or reject specification conformance.

Common practice here is to give recommendations for design etc, then to separately recommend that an 'experienced professional familiar with the contents of this report' undertakes inspections
It sits somewhere in between as it allows for an experienced structural engineer or someone else to undertake the inspection without necessarily needing the geotech

What is annoying though is that geotechs are more and more asking to review the plans before they go to council so they can issue a letter
Like, geotechs here don't know shit about foundations, so why are they reviewing the plans?
That's a separate frustration

Personally, as a structural engineer but with 13 years of field testing experience, I only recommend an inspection if I identify something of specific concern e.g. fill or variations
Usually I will just specify an 'experienced engineer' to allow the structural engineer to undertake it without needing to get me involved again
Rarely I will specify that it has to be us - that's only if the results from the testing are somewhat alarming and I genuinely believe follow up is required from us to confirm our original recommendations

I appreciate the responses. The points you have made are interesting about the objectivity issue and where geotech companies make their money.

As a structural engineer designing from a geotech report, I have always wanted the geotech who wrote the report to do the inspections. In my opinion there is a substantially better product when this happens and both myself and the client gets a better product. Perhaps that's not the case.

I just looked at 3 soils reports from different geotechs in my area and they all have statements about observing some or all of the work and if they don't the findings of their report are invalid. At least for me and the company I work for these were fairly substantial projects. The largest was a university project that had a construction cost of about $220 million dollars. The geotech company who wrote this report is fairly large locally respected company. The other two are smaller companies, but I have always thought of them as good companies. In my county there are currently about 70 emergency road repairs requiring retaining walls due to all the recent rain and these geotech companies are doing the reports on most of them.

The public works or university departments do inspections, but they often do them in house. They will say that they have the experience to do this and they may call the geotech if they feel something is out of the ordinary, but will do all the testing, etc themselves.

It sounds like this type of statement is not typical outside my area. I'm still curious if a statement like this has ever been tested in legal case.

Thanks again.

I suppose the context is very important to this
I am primarily a residential engineer at present so my comments were in that context

Geotechnical workers in the residential space are usually someone from a geology background (a technician) with one or two Chartered Geotechnical Engineers signing off at the high level
In my experience, they are pretty useless at actually understanding structures and the separation of the field work from its traditional role with structural engineers is a mistake
I do both and adopt the philosophy of not leaving site unless I know what foundation concept will work on the site - geotechnical technicians cannot do this as they don't know anything about design
In a residential context within a city there is also no reason why 99.9% of sites cannot be assessed by a structural engineer - we are still trained in this as part of our degrees and we understand the engineering science of the result
The above isn't referencing liability at all though - just my frustrations with the continual insistence on separation of disciplines to appease box ticking without applying thought to how that actually works

In the scale of work that you're talking though I would revise the above completely though
I would make sure that the contract is watertight with regards to liability and inspections and, as the structural engineer, I would be advocating for the geotech to be doing the inspections generally

Greenalleycat,
It seems my area is bit strange. The building departments require a letter from the geotech on submittal for a building permit. I can't remember if this was happening in the 90s, but at least for the last 20 years it has been going on. They have to write something to the effect that the plans appear to conform to the recommendations in their report.

Public works projects typically don't get building permits, so that letter isn't usually required. The geotech's still require that they can review the plans though.

Structural engineers IMO also don't know shit about foundations / soil mechanics...I'm not convinced the ones here know about designing structures either (and more alarmingly frequently think that they know alot about the latter). I see a decent number of retaining walls designed by structural engineers with a handy copy of their first year geo textbook and an ego. Then again in NZ it doesn't take much to convince someone you are a structural engineer (

>They have to write something to the effect that the plans appear to conform to the recommendations in their report.

They do that because it's common for structural engineers / architects / civil designers to (generally intentionally IMO but I'm not allowed to say that ) mis-interpret and mis-represent what the report says without consulting the Geotech or doing any further analysis, and then someone notices during construction. It's sort of a broken system really with everything siloed and no one really understanding the entire process. There's sort of a Geotech conservativism death spiral in alot of areas where geotechs, concerned about their already-massive liability write increasingly conservative reports and recommendations because they get cut out of the process and need to protect themselves.

geotechguy1,
I respect these geotechnical engineers a lot and I'm not casting any dispersions on them. The three companies I'm talking about I would have them do the report for my house, if I could afford to build one .

I was really just asking if that type of exclusion would hold up. Sorry if it came across in a different way.

I'm not a lawyer but I honestly doubt the exclusion would hold up in a court, if you could prove that you did all of the inspections and testing they said to do. Most of the arse-covering stuff in geotech reports is non-enforceable in an actual legal proceeding as far as I know. However it might hold up in the 'pre court, court' of opinion in the project teams - i.e. the Geotech can say, well, this is why we want to do the inspections ourselves. Perhaps enough people would buy that argument for it never to get to an actual litigation.

@geotechguy1, if you want to argue that there are a lot of shit engineers in NZ, and that EngineeringNZ / occupational regulation in general is also terrible...I will agree, don't worry
We saw the article you linked when it first came out and we weren't particularly pleased with how soft she got off - the complete lack of integrity and judgement is disgraceful to the industry

To try to be less abrasive with my point, my comments are in the context of residential buildings only really
Within this space there are not many 'geotechnical engineers' that actually practice - the majority of people employed at geotechnical firms are simply 'technicians'
As structural engineers working with these reports we find that there are obvious knowledge gaps when it comes to both the structural design and construction phases
This is particularly true in Chch where the MBIE guidance dominates so much of the geotechnical work - we find ourselves just getting MBIE recommendations thrown at us, often times lacking critical analysis of their suitability

Residential houses are generally low to medium complexity working on low to medium complexity sites within areas that have broadly well known geotechnical characteristics already
From my own experience of testing sites to design the foundations on it, I am absolutely certain that there are significant advantages when the same person is doing both roles
I see this as the desirable outcome for the industry and our clients and therefore view that we should be upskilling the foundation designers (engineers) to build on the knowledge of geotechnical conditions that we are already taught in our degrees anyway
I see this as lower risk for the project and better for the long-term future of our building stock than separating these roles

On larger scales, I completely agree with geotech involvement - the geotechnical conditions required to build a stadium or whatever are miles past the capabilities of the majority of structural engineers for sure

This is going in a different but interesting way. Greenalleycat, I was thinking you were from Australia, but sounds like you are also from New Zealand.

Do geotechs and structural engineers always battle in this way?

Na we mainly whine about each other behind closed doors/keyboards
The particular topic I've been complaining about is one that is a pet peeve in our office due to the high % of reports that we end up having to send back to the geotech to get revised recommendations for as theirs are just impractical

I don't know the answer to your actual question but I can only imagine it will be specific to your legislation
I would guess that the specific contract structure would be the first critical detail - if the geotech report tries to add in new clauses they've already contracted out of then that would presumably hurt them
Second, I would guess that it would also depend whether the identified conditions on site were actually different to what they found in their site testing
But definitely one for the lawyers, I think it's very hard to give a general answer as it will be so specific to the job, contract, and particular site conditions (especially the ones leading to the failure) that I don't think we can give much guidance here

Thanks everyone for the discussion. Sounds like I need to look elsewhere for the answer.
I wonder if insurance companies ever dictate these statements.

>They have to write something to the effect that the plans appear to conform to the recommendations in their report.

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This is what our firm focuses on in terms of what confirmation we need, wondering what the thoughts here are on this list:

- Allowable bearing capacities (for our footing designs) conform with their recommended values
- Typically need confirmation the allowable bearing capacities are actually achieved in reality once the excavation has been carried out
- Geotechnical parameters used for shoring design (i.e. WALLAP inputs) are correct (these days we're getting the parameters directly in their report and it's more just ticking off our data table matches)
- Rock profiles/layers (we show then on our shoring elevations) match their data
- Pile depths required to achieve desired socket lengths/material, as a sort of follow on from the profiles (I feel like this often ought to be confirmed on site anyway whether the right material was reached but eh)
- Groundwater levels

Can say I've not yet had values provided by one geotechnical engineer and had another doing the inspections.

The particular topic I've been complaining about is one that is a pet peeve in our office due to the high % of reports that we end up having to send back to the geotech to get revised recommendations for as theirs are just impractical

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Typically when it comes to broader recommendations (e.g. drained vs tanked basement system, the need for piled foundations, etc.) if there's a problem we raise it with the client to ask for an updated report (e.g. in one case, a site with basement 6 levels deep was recommended to be tanked, essentially threatening to kill the entire project before it even started, meanwhile every adjacent site was drained). 95% of the time however this doesn't happen, I'm wondering how/why you're running into these issues so frequently?




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Why yes, I do in fact have no idea what I'm talking about

We live in a geotechnically complex city with a high water tables, liquefiable soils all over the place, old rivers been rerouted, fill/landfills, high seismicity, variable materials
Post earthquakes the government released a bunch of 'guidance' that has standardised many approaches (good) but has also allowed many people to turn their brains off in their designs (bad)
We seem to get loads of recommendations to excavate below the water table (how do we drain it? undermining adjacent properties? cost?) for a starter

Separation of soil and foundations is a misnomer IMO as the two are fundamentally dependent on each other in the context of a building
However, there is no real pathway to becoming a 'geotechnical engineer' here - it isn't a course/degree/qualification
Maybe someone does a Civil engineering degree, enjoys the geotech papers enough that they pick up a few extra papers and maybe a masters in a geotech field?
Most likely though the people working in geotech fields come from a geology or geography background so they don't know anything about structure, only about soil
This leads to them clutching to the few reservoirs of knowledge on buildings and construction that they have, such as the government guidance

However, there is no real pathway to becoming a 'geotechnical engineer' here - it isn't a course/degree/qualification
Maybe someone does a Civil engineering degree, enjoys the geotech papers enough that they pick up a few extra papers and maybe a masters in a geotech field?

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That's exactly how it works - for present day students (myself having been one not too long ago) at the Bachelor's level there is only a civil engineering degree, get exposed to all the different fields (structural/geotechnical/transport/etc.) and maybe get some 4th year electives that ultimately don't mean too much since it's the same qualification. Doing a masters is how you get a more specific education in geotech or structural, but it's not needed to work as one so the general path is just learning everything on the job. I'd probably wager that grads fighting over grad programs results in more people looking into exploring geotechnical roles since it fits their degree, compared to genuine interest

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Why yes, I do in fact have no idea what I'm talking about

I know that the uni education barely scratches the surface of the real job for civil, structural, or geotechnical, or probably any career really
It was just a comment that true 'geotechnical engineers' are very few and far between
The majority of the people in the field come from a science background, even the ones that eventually get recognised as CPEng
So there is a lack of actual engineering knowledge in that area of the industry