I am a civil engineer working for a Contractor in Vietnam

Dear All,
I have a question related to the measurement method in my project as follows:

In our preamble of the Bill of Quantities statement measurement method for piling work as:

“Measurement of piling shall be by the length of piles installed from the underside of the structure reinforced concrete base to the level of pile toes shown on the Drawings or required by the Specification.”

In the design drawings shown toe’s level and estimated pile penetration length from cut-off level to pile toe; After driving the test piles and static load test, the pile toe’s level and pile penetration length are revised (shorten); But in the mass piles pressing, the actual pile toe level was shallower, pile penetration length is shortened again, and the length of piles to be cut off was more.

The question is, in this case, the length of piles to be measured for payment is: option 1. up to the revised pile’s toe level after pile testing or option 2. the actual recorded during mass pile pressing. As my understanding option, 1 will be applied, but the project engineer measured it as option 2.

Please kindly support me with your opinions

Thank you so much!
 

Dnyan Deshmukh

Staff member
Piles are made at locations shown on drawing but the depth is dependent of required strata so the piling work is measured as per option 2.

Payment is made against what is measurable at physical location and not as per the drawing. you may refer drawings for measurement in cases where the dimensional deviations will not be there such as slabs and columns do have fix dimensions.

Say the pile has to go up to 10 meter depth as per the drawing, and at actual location you drilled 15 meter pile.
You need to pay for extra 5 meter depth even though your drawing says drill for 10 meter.

In similar way if instead of 10 meter you got a strata at say 3 meter, contractor will never ask you to pay for 10 meter because it is shown on drawing as 10 meter.
The payment is done against physically verifiable works by taking actual measurement's.

Defining the depth on the drawing for pile could be a serious issue because its a minimum requirement and if the contractor is not going to that depth due to his machinery problem like he cant dig, in case anything happen to structure, the engineer getting that work executed will be held responsible.

So make sure the structural consultant do revise the drawing for the minimum depth of the pile which you achieved at site. so he can verify his superstructure design and if required will make changes in design.
 
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Thang Nguyen, my response differs a bit from Dnyan's, but this is a great topic for discussion.


With piles, there are always 2 criteria that need to be considered when it comes to pay provisions:
--The pile order length
--The pile driven length

The Contractor, when ordering the piles, has to be given the pile length. Either the length is provided by the Engineer in the contract documents, or test pile(s) are driven to determine/better-estimate the anticipated length of piles required, and the result of the test piles is used to refine/determine the order length.

The driven length is typically (for the agencies that I work with....) a separate payment vehicle. If a pile drives short, the Contractor is paid for the full length of pile that he ordered & delivered but the driven length is paid for what it was, and the cutoff length is a simple result of achieving bearing before the entire length was driven. If a pile drives longer than the ordered length and requires additional length to achieve bearing, the Contractor is paid for the additional pile material PLUS the additional driven length PLUS the cost of the labor, equipment & materials needed to splice the additional section of pile onto the initial pile

My reading of your specification, the key is "...to the level of pile toes shown on the Drawings..." The Contractor ordered the piles based on the lengths shown in the drawings, so that should be the payment length. If the piles drive short and bearing is achieved at a higher tip elevation than the design engineer anticipated/specified, that's simply a field condition that resulted from the operation, but the Contractor should not have to absorb the costs of the extra pile length that wasn't required to achieve bearing. All of the lengths (ordered, driven & cutoff) and the finished pile tip elevations and bearing values achieved should all be measured & recorded in the project's records & as-built drawings.
Cheers!!

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Thang Nguyen, my response differs a bit from Dnyan's, but this is a great topic for discussion.


With piles, there are always 2 criteria that need to be considered when it comes to pay provisions:
--The pile order length
--The pile driven length

The Contractor, when ordering the piles, has to be given the pile length. Either the length is provided by the Engineer in the contract documents, or test pile(s) are driven to determine/better-estimate the anticipated length of piles required, and the result of the test piles is used to refine/determine the order length.

The driven length is typically (for the agencies that I work with....) a separate payment vehicle. If a pile drives short, the Contractor is paid for the full length of pile that he ordered & delivered but the driven length is paid for what it was, and the cutoff length is a simple result of achieving bearing before the entire length was driven. If a pile drives longer than the ordered length and requires additional length to achieve bearing, the Contractor is paid for the additional pile material PLUS the additional driven length PLUS the cost of the labor, equipment & materials needed to splice the additional section of pile onto the initial pile

My reading of your specification, the key is "...to the level of pile toes shown on the Drawings..." The Contractor ordered the piles based on the lengths shown in the drawings, so that should be the payment length. If the piles drive short and bearing is achieved at a higher tip elevation than the design engineer anticipated/specified, that's simply a field condition that resulted from the operation, but the Contractor should not have to absorb the costs of the extra pile length that wasn't required to achieve bearing. All of the lengths (ordered, driven & cutoff) and the finished pile tip elevations and bearing values achieved should all be measured & recorded in the project's records & as-built drawings.
Cheers!!

View attachment 4004
I highly appreciated your comment! I am going for a final discussion with the Employer related to the topic.
So I would like to get your suggestion on my understand that rule of measurement is likely a lumpsum measurement in which the quantity has been fixed base on the design drawings levels (The specification says nothing). The Contractor gets the same payment if the pile toe's shallower or deeper than the estimated in the drawings. Do you think my understanding is correct in this case?
Thanks a lot for your comments.
 
I highly appreciated your comment! I am going for a final discussion with the Employer related to the topic.
So I would like to get your suggestion on my understand that rule of measurement is likely a lumpsum measurement in which the quantity has been fixed base on the design drawings levels (The specification says nothing). The Contractor gets the same payment if the pile toe's shallower or deeper than the estimated in the drawings. Do you think my understanding is correct in this case?
Thanks a lot for your comments.
Thang Nguyen, if the pile is paid as a lump sum, that's a whole different conversation, I've not had a job situation where that is the pay provision, the agency specifications we use for piling are always linear measurement (such as US FOOT). Lump sum pay items are easy when there is little/no variability in the installation parameters, like a storm sewer manhole or an electrical controller panel - Those are elements that can be well-defined and don't have any site-based variability. Piling, though, almost always has some degree of installed-length variability given that soils, by nature, are typically non-homogeneous, and don't really lend themselves to providing conditions to install an EXACT length of pile for each and every pile.

But, if you are saying the the contract that you are working pays for piling on a Lump Sum basis, the first thing is to check how the Engineer wrote the specification for it - What is included in the lump sum?

Let's look at a potential Lump Sum scenario for a pile. Let's say, your design drawings show the design length of the pile to be 20 M and the pay provision is 1 Lump Sum, or 1 Each - For this pile to be fabricated, delivered & driven and be in compliance with the pay provision, unless the pile achieves design bearing at EXACTLY 20 M, then technically, the Lump Sum / Each isn't valid since the scope of work which requires EXACTLY 20 M of piling to be installed wasn't performed. Not 17 M and not 24 M, but 20.0 M. I could see the Contractor making a claim that his Lump Sum price does not include extra pile length if the pile drives long, or that it doesn't include the time it takes to cut-of the pile length if it drives short, his price is based on installing a 20.0 M pile.

My opinion: If a pile drives short, there may be some scrap value of the cut-off portion that the owner/agency could ask to be reimbursed but typically, there isn't a cost issue that develops for short drives. If, however, a pile drives long requiring the contractor to acquire additional length of pile AND spend the labor & equipment time to splice, it could be construed as additional work not anticipated Lump Sum pay item. Again, the drawings, contract & technical specification requirements will be the primary documents referenced to make the determination.
 
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