Dispute Resolution/Improper Compaction Testing

[Captain37]

Hello all, I am a heavy/highway contractor and I am preparing a DRB Response. My claim is that the owner project representative improperly tested compaction on embankment we were building in order to cause false negatives (failures). This caused my co. to incur considerable monetary damage. I know that procedure is critical when using a moisture density gauge, but my question is: How critical??? Note: The inspector did not perform proctors on half of the tests taken when the owners specifications outline the specific procedure to follow.....??? Thanks everyone!

 

[msucog]

while i'm not familiar with your specific project specifications, proctors are typically not performed for every single test. they are usually performed on soils determined to be "different" than previous proctors or if it is known/suspected that the soil has changed. from my experience as a geotechnical and construction materials testing engineer, i have never seen and would never fail a test without justification. the term "fail" is not simply restricted to a singular test end-result. there are several factors that can fail a test other than the final number. certain observations by the onsite geotechnical personnel can be justification to fail a test. the contractor's actions/inactions can fail a test.

i'm a little curious as to what magnitude monetary damage you incurred. if the tests failed, then i would expect that grading activites halted until that area/lift was remediated or corrected. was the soil too wet to achieve compaction? can you provide a few more details of the circumstances?

 

[Drumchaser]

Hey cap

How critical is the procedure?
This is not an easy one to answer, especially if you do not know the procedure. (what part was poo poo'ed)
The gauge should be documented as stable. (you need to do some Troxler googling) The procedure should be done as stated in the owners test procedure, and as outlined in the gauges operators’ manual.


“The inspector did not perform proctors on half of the tests taken when the owner’s specifications outline the specific procedure to follow...?”

I am guessing the spec.s required sampling and Lab testing in order to obtain Moisture Density Curves/Proctors from Pit and or Cut areas used for embankment.

If tests were failing routinely, someone (your folks) should have verified which proctor the tests in question were based on.

There “should” be supporting documentation representing at least some of the alleged improper tests. If you can acquire it.

If you are saying “after the fact” that you were dealt with unfairly and cannot prove it, well you may be out of luck.

Did anyone witness testing? Specific comments?

 

[BigH]

An interesting point, in my view, is that a certain "percentage" is permitted to "fail" in a statistical sense. In India (and this is outlined elsewhere in many of the state DOT manuals on compaction) we used an average of 10 to 12 "tests" on a single layer (using the nuke). The average had to be greater than "Spec + 1.65xSTDEV)" If this happened, the layer was passed even though single values could be lower. (I don't have the exact formulation in front of me at present - it could differ from that above) but it is analogous to concrete testing where the average of the last three test results have to be greater than the spec value but a single value could be lower by up to 500 psi low.

Too, the nuke should have been calibrated against, say, the sand cone (which most consider to be "more true") and the moisture content should have been calibrated to known values (taken from field tests). These aspects have been discussed in other threads on the issue of using nukes. Do you have details on the last time the nuke was "calibrated", it's repair history, leak tests, etc. These are issues that you can bring out - not that they are, in themselves, a touchdown, but bringing out these kind of things that should be in the testing company's SOP on QC testing might be appropriate to show doubt. Did the QC testing company have a SOP or QC Manual for such testing? Did (do) they follow it?

Was there questionable differences in the delivered material's grain size that might suggest different MDDs be required/used? Did you, as a contractor, carry out any QC testing for your own records? Most contractors on projects I have been working on for the last many years are required to carry out QC testing - the client or engineer provide verification testing for QA purposes. Was this the case? There are differences permitted from your QC and their QA verification testing that wouldn't "fail" your work. Did you carry out trial compactions, i.e., 4 passes = X% MDD, 6 passes = Y%, 8 passes = Z%?

All things to consider.

 

[Captain37]

Hi, all! I apologize but the main discussion on this thread is in the Earthwork/Grading Engineering Forum. Sorry...This was my first post.