Foundation Observations 2

[BSomers]

Are there particular guidelines on who can perform a residential foundation observation? I was trained and sent out to do them as an E.I.T. but I am wondering if it is something that could be done by an experienced soils technician, or is it something that should be done by a P.E.?
For example, I have several subdivisions that are being built on gravely soils and I would feel comfortable sending a well trained soils technician as long as he took good pictures and gave me a call while he was on site. I have not come across any particular guidelines, and I am confident that the city inspectors I have worked with in AZ and UT would not even notice who performed the observation as long as the letter were signed by an engineer.

 

[oldestguy]

In my experience well experience technicians have done a "check" on soil conditions to verify that what is at footing grade is the material found in the original soils testing by either test pits or test borings. And yes, each of these residential sites did have such an investigation. If no such investigation and an important structure, a PE was used. A few residential contractors routinely asked for the PE, since that more or less eliminated any delays possibly caused by a "know it all" municipal inspector. Having dealt with some of them and their "quirks", once burned that was the routine. Electricians routinely would leave a junction box half covered, etc. just to give the guy something to complain about.

 

[BSomers]

Thanks Oldestguy. Most of what we are doing is what you first explained. A soils report for the site or subdivision already exists and we are performing an observation to ensure that foundation subgrade soils are the same as those encountered in the original soils report. If there are no anomalies, the letter we send out basically says that the bearing pressure and construction recommendations from the original soils report remain valid.

 

[geomane]

We have experienced engineering technicians perform foundation (shallow spread footings and slabs-on-grade) inspections routinely for residential projects. The tech's test the soils by means of nuclear density gauges, dynamic cone penetrometers, drive sleeves, speedy moisture testing, proof-rolling, and static cone penetrometers/probe rods. Sometimes percent compaction is specified, sometimes a bearing capacity. The engineers get involved most of the time when bearing capacities are spec'd.

 

[Ron]

BSomers....check the "responsible charge" section of your state law. In most states, some routine observations can be delegated to a qualified EI or technician, as long at the PE truly has responsible charge by your statute's definition.

 

[oldestguy]

BSomers: I once got chewed out for using the word "ensure". Was told, "We don't insure anything".

 

[Ron]

OG is right. Ensure is one of the many "oh no" words that are taboo, particularly in the geotechnical and materials engineering worlds. Ensure and other taboo words have a legal meaning that often goes beyond what we as engineers intend. "Inspect" is another taboo word. The alternative is to "observe".

Another common one is "review". As engineers, we usually intend it to be taken in a cursory fashion. Lawyers take it to mean "determine the adequacy of what is reviewed". We should always qualify your intent, such as "the data was reviewed for initial information only and not for its adequacy or applicability".

Keep in mind that lawyers are wordsmiths, we engineers are not. Be very careful in wording reports of any type.

 

[geomane]

We typically use phrases such, "the areas inspected appeared to be in compliance with project plans and specifications..."

 

[Ron]

jmcc...why not use "observed"instead of inspected. "Inspect" implies a greater level of effort and carries a greater duty to address essentially all potential issues. Then if you miss something you get tagged with negligence. If you "observe" you limit your scope to only what you saw.

 

[emmgjld]

A typical phrase I have used, following my Father's of many years and adjusted as the 'taboo words' have been recognized during litigation, "My observations of the (foundation, foundation drain, etc.) indicate it was constructed in substantial conformance with (project plans, our foundation design, our previous recommendations for this site, etc)".

 

[Ron]

emmgjld....good statement!

 

[geomane]

Ron, I believe you are right. I will look into changing the wording of our CSD reports when I start signing and sealing the reports.

 

[BSomers]

Thanks everybody. I appreciate the advice on word-smithing. Ron, I'll look into my states "responsible charge" clauses to make sure but from all of the comments, it seems fairly common for technicians to perform observations with proper oversight.

 

[BigH]

To me, it is always amazing that checking the foundation is typically limited to a few inches when the footing "capacity in shear" or "allowable pressure in deformation" go much deeper than the kick of the surface. Basically you should be looking to confirm that the founding material is as expected, that the excavating contractor has not overdug and then tried to pull a fast one and that the surface at foundation level has only minimal (thickness) of possible disturbance. Be very careful in areas where the stratigraphy has shown wide changes iver short distances.

Also for some sites that have a strong layer over a softer layer and the design is calling for or relying on sufficient thickness of the stronger layer. You need to keep vigilent on this type of situation.

 

[OldBldgGuy]

In Ontario, PEO gives us guidelines for construction review, site inspections,etc. Anyone can do them, if you trust them to give you the right information to sign off on; you can send a dog with a note in its mouth & a camera. After all, it's only your neck. However, the guidelines and sample reports are very well written to explicitly state (in the appropriate case) that it was a review, not an inspection. Here's a list that covers a lot of territory

http://www.peo.on.ca/index.php/ci_id/1834/la_id/1.htm

 

[BSomers]

Great comments Big H. We have collapsible soils in some locations here in Utah and I am a big fan of having the excavator pot-hole down below the footing grade when I do observations.In the areas with known collapsible soils I take samples and run collapse tests frequently as well.

 

[EireChch]

In the UK and NZ, technicians undertake foundation inspections routinely. Testing often comprises dynamic probing, shear vane testing, nukes and also Clegg hammers. We would also have to confirm that foundations are 0.6m below finished ground.

The engineering would then prepare an "observation letter" foundations have been constructed in accordance with our recommendations and that ground conditions are considered appropriate.

I had an interesting chat with a contractor on one of our infrastructure projects, i would have to go to site twice a day to inspect different portions of work i.e. depth of piles, checking retaining wall heights etc. We joked that it would be easier if he had a go pro fixed to his hard hat and that he could just measure things on site and i could just observe them via live video link form the office. I joked with the guy that he would probably be bending the tape measure down the pile hole to add a few hundred mm and make sure it achieves the target depth. If he done that over say 50 piles he could save some concrete and material disposal costs. It wouldn't be beyond some contractors which i have dealt with in the past.

They way things are going with technology video link etc could happen. It will never replace the real thing but could aid in reducing site visits on minor portions of work.

We have seen it on one job where we had a drone inspecting a steel bridge. It could easily pick up cosmetic things like rusty connections etc. Once they were identified we could arrange for a physical inspection.