Geotechnical Report Reference 2

[nbr1]

Design documents often make the reference 'Reference Geotechnical Report'. As an example, an underslab detail may indicate the subgrade to be prepared per Geotechnical Report or similar language.

It is my understanding that the geotechnical report does NOT constitute a design document; even where it may be referenced in the specification and/or drawing.

Interested in other's experience with this issue.

 

[JedClampett]

You are correct.
In my opinion, it's a cop out to refer to the Geotechnical Report in the design. It's our job as EOR's to convert the Geotechnical Report to a design document.
If you have looked at a Geotechnical Report there are a lot of "mays" and not enough "shalls."

 

[Rockmynci]

I would agree that using another organisations interpretation within your own design is foolish, without first going back to basics and justifying the approach. However...

Reference to 'Geotechnical Report', can constitute a wide variety of information. If its a factual report that is referred to (boreholes, trial pits, lab testing etc, without detailed interpretation of results), this must be considered a contract document?

 

[jgailla]

From a civil point of view, I agree with Jed.
The geotechnical recommendations should be used for design and to produce drawings and specifications based on those recommendations. To simply refer to a geotechnical report in lieu of providing correct drawings or specs is begging for a claim. It also appears lazy, and I would be careful dealing with a lazy engineer.
It is common practice, however, to reference the geotechnical report as part of "Information for Bidders". This both helps the contractor for earthwork, trench issues, etc. and prevents the contractor from claiming an unforeseen conditions change order assuming soils issues are picked up by the geotech.

 

[JedClampett]

The way I understood the question, the design required that the contractor look at the Geotechnical Report to prepare the subgrade for a slab-on-grade. As I said, to me that's out of bounds.
This is different than providing the Geotechnical Report so that the bidders can get a complete idea of what information the Engineers know. For instance, maybe there's rock near the surface. Providing the borings discloses this. This doesn't affect the design, but certainly affects construction. If you know that and didn't disclose it, you could be facing a claim.
The downside of providing the Geotechnical Report is that sometimes there are options you don't need the contractors to know. If you picked pile foundations when spread footings were given as an option, don't think the contractor won't be in the owners ear, asking to change.

 

[Ron]

JC and jgailla nailed it. Many geotechnical reports have caveats about third-party reliance (legally they probably don't hold water, but they are there and interpretable by the court).

 

[BigH]

As one of those "geotechs" one of the reasons the caveats and the mays, etc are in the report is that many times (most times) the investigation and the report are done before the structural engineer even knows the detailed loading, sensitivity to settlements, etc. Clearly, a geotechnical report that is "factual" is the first step - then a preliminary interpretative report so that the design engineer may look at what types of foundations or foundation treatments are needed. Once the framework for the foundation design is sorted out, then a detailed interpretative report with very specific recommendations can be provided. Most of the time, the latter seldom happens which is why in this forum, we have so many responses to "check with the geotechnical engineer"!!

What should be part of the contract documents, in my view, if the risk warrants, is a base line geotechnical document which describes to the best way possible what problems are anticipated and provides the scope that up to a specific problem, it is the contractor's responsibility and subsequent to that the onus is on the owner. Such as the percentage of an excavation that has large boulders (say greater than 1 or 2 m3) - up to that amount, the contractor must have included in his price; however, if this is exceeded, the cost would be borne by the owner. Similarly about excavation in rock - what percent is rippable; what percent would require blasting, etc.

I agree, though with JC and jgalla on the "cop-out" point of view.

 

[Dirtguy4587]

While the Geotechnical Baseline Report approach is common, I have seen a shift away from that approach in the mining/heavy civil industry. I've been involved with a number of contracts for "earth-moving" where the geotechnical data reports have been provided as part of the contract, but the onus is shifted to the contractor to guarantee performance based on the data only. No interpretation by the owner is included in the contract documentation. And counter to the GBR approach, the contract holds the contractor to given "production", and if any unfavourable geotechnical conditions are encountered, that risk is held by the contractor. Initial reaction might be that this becomes more expensive, but I have found that in the case of large earth-moving contracts where it is difficult to have enough drilling to complete an extensive interpretation, this becomes a cost competitive method.