Margin of Error 1

[Samspots]

We are currently arguing with an owner over the deviation of a measurement on a plan detail. It was on a bridge project with 50 piles. The detail states that the pile lenght shall be 61.5' +/-. 14 of the piles required splicing of additional pile onto them to achieve bearing. (Some piles were as long as 93 feet) The Owner insists that +/- sign on the plans means it is open ended and the pile lenght can vary from that to whatever is needed to achieve bearing. My research indicates that it means the next significant number or 62. Does anyone know where I can get a definition or engineering opinion regarding the meaning of a +/- sign on construction drawings?

 

[CarlB]

To me "+/-" means "more or less". Given they used a decimal of 0.5', I further take it to mean +/- 0.5', meaning 61' to 62'. If it was meant to vary by several feet, why use a ".5"?

I don't think it "legally" means anything other than it does not need to be exact, as the correct way to specify a tolerance would have been "+/- 2 feet" or something like that. When something in the documents is not clear, the courts almost always find that the contractor is free to interpret it.

 

[MiketheEngineer]

IMHO - a foot or two at the most!

 

[rday]

I usually assume with just the +/- and no qualifier that the allowable variance is in the last sig fig. In this case .5 so between 61 and 62 feet.

CarlB is right about proper specification on tolerances. ANSI publishes standards on tolerance for many items. Try them for something.

 

[jheidt2543]

I agree with that +/- as generally used means plus or minus the last sigificant figure.

All contracts I've seen that involve piles have unit prices for all sorts of things like load tests, additional piles, additional lenth of piles/lineal foot etc. Am I correct that your contract did not?

I believe someone is trying to pull a fast one on you. No one reasonablly familiar with construction would try to make the argument they are. I think I would ask them to compare the cost of the extras you are claiming vs the cost of litigation - where even if they were to win, everybody loses.

 

[jheidt2543]

Another thought, look at the "Changed Conditions" clause in your contract; you ought to be able to get some relief there too. You did have a contract?

 

[BigH]

Is the contract a BOQ contract - you get paid for the quantities that are "used"? What is the "seating" criteria for the piles? If you don't get acceptance seating at 61 and have to drive to achieve the acceptance seating, you would get paid for the extra length. Otherwise, ensure EOR or representative gives a site instruction to drive beyond 61 +/- in order to get the seating. If no sign, claim.

 

[Drumchaser]

Sounds like your pay method for PILING is something other than by the Linear Foot? I am confused as to why you would be argueing with the owner unless it involves monies due to you or your company.
In my nightmares with piling (H and various sizes of square prestressed concrete)the two goals were to achieve bearing and reach plan pile tip elevation. If build-ups/cut offs or splices were required they were paid for at an increased pre-established bid price.

It has been my experience that when "plus or minus" is used it is follwed by another value expressing the range of deviation allowed. I don't recall seeing +/- relating to pile lengths.
My guess here is you are on the hook for materials and labor for the additional lengths? Change Order No. 1.

Hope this helps.

 

[DRC1]

If you submitted furnished lengths for approval as part of your submittal package and they were on the order of 65 ft I would tink you were in good shape. If they approved the lengths proir to driving you are in better shape. As a piling contractor, I would not expect a 50% overun and a splice to be included in the +/-.
However, your quote for piles should address what lengths you are furnishing and driving, if splicing is included, or if not how it gets paid, and how you get paid for both exceeding the quantity and underrunning the quantity. Typically the cost for overrunning is significantly higher than the credit for underunning, so they should be two different numbers. Quote should also address what are obstructions and how do you get paid for them, and how is driven length measured, who does cut off and how do you get paid for cut offs.

 

[SlideRuleEra]

As a former Owner's representative, I'll suggest a slightly different way to present your request for extra payment.

Forget about the overrun on the 14 piling. Look at the total linear footage that was called for (50 piling @ 61.5 ft/each = 3075 total linear feet). Base your request on the total length of piling driven versus the "contractual" quantity of 3075 ft. (I assume that the total driven was significantly higher than the contractual number?)

The Owner may be more receptive to change in the "lump sum" quantity of pile actually driven.

Since you have not mentioned the other 36 piling, the Owner may view your focus on extra payment for the 14 piling as quibbling

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[msucog]

i'll throw in my two cents. first of all, the 61.5+/- for estimated pile length means "the data indicates that 61.5' might work. it could be 50' or 70' but 61.5' is the best estimate we can give you". from a geotechnical standpoint, the +/- means to whatever depth needed for bearing but from a contractual standpoint, the +/- means "give me an estimate based on this assumed depth and we'll go from there". now personally, i wouldn't estimate a pile length to the 1/2 foot anyway...i'd round (probably up) to the nearest 5' or so unless you've already got boring data at each/most pile locations. i've seen owners try similar tactics with skimpy geotech data...but if the owner would've spent the appropriate monies during the exploration phase, they would not have been so surprised by the variance. or maybe the necessary exploration was performed and this is just one of those oddball scenarios that happens when you really get in to it...since you never really know until you actually do the work. as always though, contractors will play their games too. secondly, i would hope the contract wasn't so exactly written that the pile contractor couldn't get paid for the additional footage (assuming the total footage was much higher than the 3075'). if the contractor agreed to a lump sum of $xxxx regardless of the bearing depth, they might be at the mercy of the owner. likewise, if all the piles went to 50', then the owner should not pay for the leftover footage. but if the contract said that the owner would pay $xxxx regardless of the bearing depth, then the owner would be at the mercy of the contractor.

i would hope that both sides would use "reasonable" judgement when confronted with this issue. there's a lot of if's in this scenario and perhaps there's more to the story since it's difficult to fully explain both sides of the issue via internet.

 

[DRC1]

Muscog does a good job of pointing out why it is nesseary to have an equitable contract for deep foundations. Even with detailed geotechnical studies, there are always surprises and a good contract clearly defines what the basis for the bid is and how adjustments will be handled. The best contract, in my opinion, is one that has a good geotechnical investigation a clear scope (for example what constitues an obstruction, what tolerances are required for the piles) and a lot of unit prices to handle changes.