Monday, January 2, 2012

RE: Foundation piles deviations

The ACI 117 is too liberal for many applications.  As an example, I use the AISC tolerances for anchor rod tolerances.  Auger cast piles are a different lot than other foundations, and ACI 117 just does not cover it well.  i.e. There is no other foundation of which I am aware that the reinforcing steel is placed after the grout is in place.  There is a likelihood to have bulbs close to the surface due to the pressure (thus ACI 117, Section 3.5.2 is impossible to maintain).  The grout is measured for fluidity and workability with a funnel and the rate of flow is measured.  The reason that I pointed to the DFI is because it covers more aspects of auger cast piles than the ACI 117. 
There is a lot of good free stuff, if you know where to find it:
There is another good document that should be referenced, but it does not have that much on tolerance.  It is by the FHWA.  The best approach is to use the FHWA document for the QC plan with the DFI or the UFGS (below) for the specifics on tolerance to develop a QC plan.  An additional document that has specifics on auger cast piles (including tolerances) is the US Army Corps of Engineers guide specifications. 
This is another good free document on deep foundations:
Anyway, it is up to the engineer to put the specs together for acceptance criteria.  If field inspection is a problem, the engineer should have approval authority of the inspectors and call them to task if there is a continued problem.  Most importantly, the variations should be reported immediately so that remedial actions can be taken.  Remedial actions now should be developed collaboratively.  And the engineer should be paid for any additional work. 
I had a similar situation in LA on a project in the early 1990's.  The general contractor selected an auger cast pile contractor that was not qualified.  After 6 months, the original auger cast pile contractor was fired.  The GC had to pay for all of my time in the meetings and for the remedial work.  Then the GC hired a qualified contractor and the work was completed in 90 days.  And the subsequent work was all done within specifications.  The GC lost a lot of money by selecting the low bidder that did not have the qualifications.  I did not have approval authority until after the project went badly.  The client then gave me all the approval authority (for a fee).  The rest of the project went smoothly. 
Regards, Harold Sprague

Date: Mon, 2 Jan 2012 10:47:03 -0600
Subject: Re: Foundation piles deviations

On 1/2/2012 10:44 AM, Bill Polhemus wrote:
On 1/1/2012 7:47 AM, David Cohen (Baran Raviv) wrote:

Almost each of the pile was done in deviation from the original design location I'd designed, about 2% to 20%

Do you know a kind of rectification for this kind of installation errors, or just to execute some other ones?

Harold mentioned DFI. I didn't see anyone mention ACI 117, which contains Tolerances for concrete work including bored pile foundations. I think it's pretty complete.

As far as rectifying the problem, here in the states, "the contractor proposes and the engineer (as representative for the owner) disposes." In other words it's not for you to come up with remedial methods, it's for the contractor to propose them and you are responsible for acceptance.

The contractor SHOULD have enough money in the bank to hire his own engineer if he needs help with that, FWIW.
Oh, and to provide emphasis:

This habit of contractors to screw up and then expecting the OWNER'S engineer to fix his mess is absurd - and rather childish if I do say so myself.

Putting you on the spot, and shifting some of his liability for his mistake onto you, is more than absurd, it's insane. Don't fall for it.