How can drill crews cheat?

[oldestguy]

I suspect cheating is rare, but what can be done about it for drill crews out there without direct inspection? In the past I was with a state DOT and we had crews and later a consulting firm with our own crews. The latter situation was more likely for problems I found.

I have only had to deal directly with this once, but have heard plenty of stories about "double sampling" and such.

The urge to get to "Miller time" at the end of the day is not good.

With the constant push to stay competitive these days (and for that matter for many years now), besides knowing the guys quite well, what can be done?

I had my ways of checking, but you can't be there all the time.

A recent thread about hollow stem augers brings this to mind.

 

[BigHarvey]

It would be better to take the problem the other way around. I do not know the situation in the US but I can talk of France. You can see SI contracts with too low prices and you can be sure that the SI contractor will do for the money he contracted. I am a foundation contractor and rely on SI for pricing my contracts. Sometimes when I get a SI report done by some companies, I prefer not to put a price because I know by experience that the information given is not reliable and I don't want to spend my time in a law court to try to get an indemnity !
The only way to prevent cheating is constant inspection , but it might be preferable to pay the just price to a reliable contractor and save on inspection !

 

[BigH]

Oldest Guy - Interesting question and is similar to what we experience with many geo reports I see here - not only the drilling but the lab testing. I'll put my thoughts together and reply soon.

 

[oldestguy]

Big H

Hey, you hit on another part of the work and in the lab I suspect even more corner cutting might occur, having seen some of that also.

 

[fattdad]

Outright cheating is to double sample and do have the footage. I've heard of this once in my career and figure it to be rare.

Cutting corners is likely the bigger problem when drill crews are out on their own. Here is my list of problems:

Drilling where access is easy, rather where the borings are supposed to go. I did a project and the driller "thought" he was at the rear of the site, but was about only half-way to the back. I compared a gps of the borings to the "location map" and it wasn't even close - I mean by a long shot. Over half of the site was un-explored.

Using the sampler as the plug or drilling without a plug.

Marking "6-in" increments on the rod using the calibrated eye method. You know, just grabbing a piece of chaulk and making three or four marks about 6 inches apart.

Using how ever many turns on the cat-head they want to.

Not taking the time to clean out the hole and getting too much slough in the sample barrel.

Sideslope drilling where the rear of the rig is downhill and not using a duce auger to make up for the rig height. The depth of 5 ft just isn't 5 ft!

Not cleaning out the sampler when drilling muck, just knocking out what falls and then using it again. The underlying sandy layer (if present) ends up with a sampler that is all comingled with the overlying slop.

Not taking any time to document the position of the water table.

Not taking the time to document changes in drilling.

Just a general lack of any note-taking to capture fugitive information.

I'm sure I'm overlooking a few additional items.

f-d

¡papá gordo ain’t no madre flaca!

 

[oldestguy]

fatdad:

Those problems sound familiar.

Back before nice big rigs with drilling capability, the firm I was with did a lot of 15 - 20 ft. holes by just driving the spoon 2 ft. at a time and withdrawing. Spoon was 24" inside and using that for the drilling method, if cave-in was not happening. As rough as the N value is, that was acceptable then. The rig was a tripod and a cat-head on back of a truck.

I happened onto a new school drilling job site and gave instructions for the next job, needing to be done while out away from home. Faces dropped at the idea of not getting home that night. This set off a question in my mind.

So, I went on my way, supposedly, but came back and parked behind a barn about a mile away. With my spotting scope, I watched the next two borings being done. Low and behold the spoon was pounded by the 350 # weight (normally for casing) all the way down. A little fooling around was done and some time spent sitting in the truck making out the fake log.

Of course, all hell broke loose when I came back again.

What it tells me, along with some other crew problems cheating, ya gotta keep the moral up and treat the guys right. At times, it means some extra breaks due to that form of life, as compared to the local workers. It sure is easy to cut corners out there if one thinks no one will know the difference. How to get what we want is sure difficult.

In the lab, something that is difficult to stop, is a very experienced tech skipping some of the many runs with the proctor test and faking them or similar fakes. He might be close, but again, it comes down to personnel relations and keeping the crew happy. Problems still can occur. It ain't easy is it

Then comes those with a drinking problem. The answer is the pink slip.

 

[moe333]

Field testing is another area where cheating occurs. I have seen made up density/moisture test reuslts, from the sand cone and the nuke. Sometimes the tech. will fake a result either because he/she wants to go home, or he/she just doesn't like confrontation, or the visual performance says one thing and the results say another, and they don't want to deal with sorting it out.

 

[fattdad]

on the matter of field density testing. Actual field data for a failed retaining wall (I just present one set of data for reference, others are no better, however):

f-d

¡papá gordo ain’t no madre flaca!

 

[BigH]

Back to the drilling . . . It is difficult, especially in soil, to confirm cheating - cheating can also mean many differen things (1) Drillers start at 0800 but write down 0700 on work sheets - similar on ending the day; long lunch (2) identify that they have drilled boreholes to required depths, but take only some split spoons in a couple of surface holes - and split them up for other samples, as examples. Not much you can do on (1) unless you are quite familiar with drilling techniques and would have a good handle on progress rates - i.e., if you have experience that 25 ft SSA holes can be drilled in 1.5 hours - so you would expect 5 holes to be drilled in a day and they only get 3 or 4.5, then this might send up flags (wash boring in difficult materials would be a nightmare - we sometimes only got 5 to 7.5 ft/day . . . For (2), if you have a good understanding of likely subsurface conditions and soils "provided" at certain depths aren't what's expected (i.e., all material is soft brown clay) and you know you are under the water table (grey clay), or that you would expect lower samples to exhibit varves and you don't see any in the "given" samples - this is another indicator. In rock, you can at least see the core - it is difficult to say you drilled 30 ft into sound limestone, say, and have only 15 ft of core . . .

Anything about cheating by the drillers - can be overcome by insisting that you have a junior engineer or technologist from your company to log the boreholes. This, in my view, should be done anyway especially since drillers do not necessarily pay attention to critical details (i.e., microscopic seams of fine sandy silt in a coarse to medium sand layer, etc.

I've seen a lot of drilling overseas - and in general they are pretty good - techniques in Indonesia is actually to "core" the subsurface down to sampling depth, sample, then "core" again - in these cases we can actually see the recovered intermediate soils (except sands, of course). In Canada I worked for firms that ALWAYS had their own supervisors on the rigs.

OldestGuy - Cornell finally dropped a men's basketball game in the "Ancient 8" to Princeton - first Ivy loss since Spring 2007!

 

[oldestguy]

Big H:

I agree with having an engineer on the job for inspection and maybe doing the logging. However, what about outfits like I have been with for many years before being on my own(State DOT, and consulting firm with our own crews)? In these cases the morale of the guys seems most important.

In one case, some added borings were needed on a job 5 hours drive away, determined after they got home. The boss (at the time) didn't pay for their time on the road for the second trip. Later I heard that the boss paid for that mistake many times over.

As an extreme dumb thing, a hired private drill company was about to start work on an Interstate bridge site. The foreman stopped at a gas station asking for directions to the nearest gravel pit. He wanted to fill sample jars!