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Engineers and dirt balance

DPete

Senior Member
Joined
Feb 21, 2007
Messages
1,677
Location
Central Ca.
Somewhere there are engineers that understand dirt balance, not here:cool:, we have been short on the last several projects ( same engineer) anywhere from 25 to 35 %, frustrating to say the least. How many of you have the same issue? With all the hotsy totsy computer programs it still comes down to practical experience on different soil types and percentage of cut dirt over fill, this engineer has no clue!
 

lantraxco

Senior Member
Joined
Jan 1, 2009
Messages
7,704
Location
Elsewhen
Worked for an outfit years ago, went computerized, and in the hands of an experienced man it really did produce good results. Funny part was, the one partner in the company would go out and walk the job site with the prints in his hands, scratch some numbers on the back of a bar napkin, and was usually within 3-5%, about the same as the computer system at the time.

One thing about it, the computer programs are only as good as the topogs, if there's any errors in starting elevation or the survey, the computer won't know it. I remember one job where after a short meeting the general agreed to raise the elevation on the whole job by a few inches to avoid hauling away several thousand yards of excess. Nothing's ever flat in Western Oregon so nobody would ever notice, lol.
 

CM1995

Administrator
Joined
Jan 21, 2007
Messages
13,250
Location
Alabama
Occupation
Running what I brung and taking what I win
How is your contract and pricing set up Dpete? I do mostly small earth moving jobs and I have to calculate the cut/fill and import/export - it's all on me to a certain extent. If we run into unsuitable soils then it rolls into a unit price change order.
 

Red Roan

Active Member
Joined
Nov 13, 2013
Messages
30
Location
SE PA
Any unbalanced earthwork is apparent as soon as I run the cuts and fills. Some sites just can't be balanced because they are bordered by existing hard structure on 2,3 or 4 sides, and they are what they are. Plenty of other factors can come into play such as getting sewer and water to leave the site on their own accord, or entrance and exit slopes exceeding allowed grade percentages. If the engineer has a reason, fine. But if he doesn't have a reason, and the site's out of balance, by the end of the day, I'll make him looked like a smacked behind to whoever is paying him.

I've been doing it long enough that I can tell if the site is unbalanced because of the engineers ignorance or complacency, or even his unwillingness to change the design he's been working on for the last couple months. Thousands of dirt jobs give me the experience to look through the BS that contour lines portray.

If you are working the site and come to the stark realization that you're going to be short on dirt, that's your fault for not running the cuts and fills ( that's just generally speaking and not directed at the OP ). If it's the case where the owner or GC is providing quantities, I still always verify them, and if they are dictating quantities, they are most certainly responsible for any import or export required to bring the site into balance. ( and if that happens, they are at the mercy of my pencil ) And as far as topo being off, one of my first line items in an estimate is verification of existing topo. 6" low across the board on a 20 acre site can equal a lot of dollars.

I never go into a site without knowing my quantities and options before hand. I routinely bid sites with 100, 200, 300 thousand yards of dirt or more. And, there's just a host of things to do balance a site while it's being worked as well, especially a big site. Balancing a site by raising or lowering the site uniformly is child's play, raising and lowering specific areas within a site and making sure everything works is an art form.

But like you said, some engineers still don't have a clue, or just don't care. 20 years ago, it was out of hand, but most recently, most attempt to try to bring balance, but a lot of them do it on strictly surface to surface basis, and have no clue as to the importance layers and the manipulation of said layers can have on the overall dirt balance.

So, I feel your pain, and thanks for bringing up an interesting and important topic!
 

390eric

Senior Member
Joined
Feb 24, 2009
Messages
274
Location
pittsburgh PA
I know on the last few bigger dirt jobs, We did our own topo with our own equipment and they were all dirt heavy compared to the bid quantities. Talking from 20,000 to one job think was 50,000 heavy. That's a lot of extra dirt. The last job that was 50,000. Was a high side low side housing development. Total yardage was in the 400,000 yard range with out numbers. All the slopes were extended 30 foot wherever they could be for bigger back yards. We still had extra dirt at the end that ended up in a stockpile for the next phase

We also had. a job two years ago and basically the contracted stated we owed a balanced site when done. That was a pain. It was a big site, think 250,000 or so yards. Took awhile to make everything right.
 

DPete

Senior Member
Joined
Feb 21, 2007
Messages
1,677
Location
Central Ca.
How is your contract and pricing set up Dpete? I do mostly small earth moving jobs and I have to calculate the cut/fill and import/export - it's all on me to a certain extent. If we run into unsuitable soils then it rolls into a unit price change order.
We are digging an extra basin to get material (lucky to have room ), I will get a change order and get paid for it but still it runs the job a week late. The material is brown silty sand probably laying @ 75% in bank yards, we are compacting to 95%.
 

jaclo

Well-Known Member
Joined
Apr 22, 2014
Messages
108
Location
Midwest
We are digging an extra basin to get material (lucky to have room ), I will get a change order and get paid for it but still it runs the job a week late. The material is brown silty sand probably laying @ 75% in bank yards, we are compacting to 95%.

I read somewhere there are water restrictions in cali for use in compaction - any experience with this yet this year?
 

dirtfan

Member
Joined
Nov 27, 2010
Messages
24
Location
Southern Ohio
DPete:
I have been working in sitework and road building for over 40 years, and this has been a question of mine for years as well.

What I have come to understand over the last few years, is that today the availability of information on the internet, has replaced good old fashioned leg work in the field, to some degree. In many cases the owner/developer of a site will not spend funds on preliminary work, in the field, for such mapping and topo verification in an effort to make a project more cost effective. Instead the engineers will rely on existing U.S.G.S. maps and satellite photos for the site topo info and mapping of existing structures, trees, roads ect. Often some of this information isn't as accurate as it should be and leads to bad numbers for the contractor. I have seen some topo info from some of the old U.S.G.S. maps be off by as much as 10 feet in elevation. This is why I think that Red Roan is dead on with his statements about doing your own legwork and verification of topo and volume information, prior to bidding. This seems to be a cost that the contractor has to absorb, but it is better to know in advance. Even if the site was "topo'ed" with an aerial fly over, it can be off in wooded areas by varying degrees. I was in a meeting a couple of years ago about underground utilities that were not on the plans and were at elevations that conflicted with the proposed new utilities, when the owner asked the engineer why this wasn't discovered in their preliminary onsite investigation, the engineer replied that they were not paid to investigate that part of site. This told me that their wasn't enough money to do all of the investigation work that they should have.

The thing that really gets me going is that, in most spec books, you will probably find a paragraph that says something like,,,,,, ""The contractor shall be responsible for verifying all quantities for earthwork and underground utilities"". If owner/developers whether public or private wants to hold the contractor to this, then they should at least provide reliable information.

We all have been there,,, What ever happened to the "good old days" when you could count on the plans being "gospel" for the site??? I'll have to go with Red Roan on this one and say; "I feel your pain"
 

Raildudes dad

Senior Member
Joined
Dec 29, 2007
Messages
411
Location
Grand Rapids MI
Somewhere there are engineers that understand dirt balance, not here:cool:, we have been short on the last several projects ( same engineer) anywhere from 25 to 35 %, frustrating to say the least. How many of you have the same issue? With all the hotsy totsy computer programs it still comes down to practical experience on different soil types and percentage of cut dirt over fill, this engineer has no clue!

I'll wager a guess that he's not factoring in the cut will require about 25% more once it's compacted in place in the fill. If he's using an earthwork program, one has put input that factor. I started my career almost 44 years ago doing all the calcs by hand. One learned how to calc dirt. Today's "kids" just rely on computer output, don't even due a rough scaling and calcing to verify their results.:(

Several of the large dirt guys here are running a robotic gps over the sites to verify the quantities.
 

390eric

Senior Member
Joined
Feb 24, 2009
Messages
274
Location
pittsburgh PA
Raildudes dad;560914 Several of the large dirt guys here are running a robotic gps over the sites to verify the quantities.[/QUOTE said:
That's what we do. Well we use a rover that has to be held a certain distance from the ground Then you have to walk in 10' by 10' squares in a grid It records the elevation. Have a quad set up to do this with Saves a lot of walking.
 

Tones

Senior Member
Joined
Mar 15, 2009
Messages
3,062
Location
Ubique
Occupation
Ex land clearing contractor, part-time retired
I ran an earthmoving job years ago and the engineer was a real novice. We were over 50% short of dirt and finally got through to him about the problem. He came out to the job on a Saturday morning to peg out a new area for us to win some fill, He couldn't understand why the levels wouldn't work out with the contour on the plans. I explained I had already cut the fill out of that area to keep the gear running but were still short. Unbeknown he had been up until 1am drawing plans for what was already done. He ended up saying to win the fill anywhere on site, leave it tidy and he would do an ascon later
 
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