Geotechnical Peeves and Preferences

[Terratek]

Those of you who procure geotechnical services; what is your biggest peeve with geotechnical engineers? Also, what do you like most about your preferred geotechnical consultant?

 

[oldestguy]

For what it is worth, when I left a geotech firm after 20 years there and went on my own, the thing that most clients mentioned when then switched to me from the old firm was that I tried to save them money with my recommendations. Also, I was more practical as to details that had to be included with the work. The younger guys at the old firm had a tendency to "jump before looking".

 

[JedClampett]

We design sewage treatment plants. My biggest pet peeve is having to explain to the Geotechnical Engineer that if I put an at grade structure right next to a 30 foot deep tank, I'll need recommendations to avoid settlement of the shallow structure.
My second biggest peeve is reports for the same site changing over time. I.e. first phase, scarify the soil and build on grade. Second phase, over excavate 5 ft. of soil and replace with imported material.

 

[Ron]

Perceived and implied accuracy....

I see soils related stuff sometimes carried out to 3 or 4 decimal places in recommendations.

When doing lab testing for geotechnical work (consolidation, triaxial shear, direct shear, etc.) measurements are made very accurately (consol for instance...0.0001") for the purposes of plotting appropriate curves and picking up nuances of the soil. This is appropriate.

When recommendations are given for expected strengths, settlements, etc., we should be dealing with fractions of an inch at best. 2nd decimal place accuracy for expected settlement is absurd.

 

[SlideRuleEra]

After a preliminary site investigation of a difficult site, we would issue a request for professional services to geotechnical firms for a comprehensive site investigation. The firms submit details of all sampling and tests they consider essential. Even when we accepted a proposal, without change, the typical disclaimer would be at the end of the geotechnical report. Words to the effect that:
"We may have missed something, if you pay us more, we can tell you more."

Trouble is, the foundation design team had to make hard design decisions based on this "weasel worded" report.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[TehMightyEngineer]

Not specifying whether the tested allowable soil bearing pressures are factored or service bearing pressures (looking at you AASHTO) or whether it is gross or net soil bearing pressure.

Maine Professional and Structural Engineer
American Concrete Industries

http://www.americanconcrete.com

 

[JStephen]

I don't procure geotechnical services, but work with soils reports furnished by others. Generally, they seem to be pretty decent.

Occasionally, we'll get a report in that says the investigation was to see if the soil was adequate to support the structure, and they conclude, that yes, it is adequate only to complete the structure, but neglect to give an allowable bearing.

Some plusses that are really not required but sure come in handy: Showing exactly where the site is (as opposed to just locating borings on a site plan). If there's anything that can't be excavated with heavy equipment, pointing that out for those of us that don't discern it from the other information reported. If depth of footings can vary, showing allowable bearing as a function of depth, rather than just at a preferred depth.

 

[oldestguy]

More comments. Currently I review reports from two different engineers and have viewed many of them in the past. Many make the same mistake that I did back then. Too many words, now possibly to justify a bill. My mistake came when a city engineer said "I like your report. However, what is the allowable bearing capacity?" Of course that was the only info he wanted and he couldn't find it. Buried in a bunch of words.