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alexcivil (Civil/Environmental) (OP)
23 Sep 07 19:44
lots of valuable information by very porfessional individuals. i have been doing some research but i am still not very clear on the weight of fill dirt.

i am going to do the foundation for my house and i would like to estimate how much dirt i am going to use?  any formulas? ideas? comments?

How many pounds does one cubic yard of of compacted *dirt* weight?

by dirt i mean whatever the material is used to do a building pad.  any input will be greatly appreciated.  thank you.

alex



Helpful Member!  DirtPusher (Civil/Environmental)
24 Sep 07 10:25
The answer to your question requires a lot more information..

What type of "dirt"? Sand will have a different weight per unit of volume than high clay content soils. Soils with high percentages of rock fragments may also have different densities. etc. etc.

I'm not sure I understand why you need to know weight or density of the soil. Are you concerned about loads against walls?

If you just want to calculate the volume of earth required to fill an area (or to be removed), then a simple grid cell takeoff can give you a good estimate. However you need to know the existing ground elevation and the proposed ground (sub-grade) elevation at each corner of the cell.

Example:

Say you cut your building pad area into 5 ft X 5 ft squares.
At each corner of each 5 ft grid cell look at the existing elevation and the proposed elevation. An existing elevation that is lower than the proposed would indicate a fill (a cut would be the opposite).

Now lets assume that one corner shows a 3 ft fill.
Another shows a 2 ft fill
Another shows 1 ft fill
And the fourth shows a 2 ft fill.

Adding these together (3+2+1+2)=8

Divide 8 4 (the number of cell corners) = 2

2 ft is the average fill depth.

The area of the grid cell is 25 sq ft (5 X 5)

2 ft multiplied by 25 = 50 cubic ft. or about 1.85 cubic yards.

Truckloads of dirt are usualyl measured in cubic yard (cy)

Repeat this for each grid cell and add all volumes (cy) together for a total volume. Be sure to rember that measured in a dump truck is "loose" measure and when compacted will equal a lesser volume and will vary with the type soil used. You might want to contact a grading contractor to get an idea of the types of soil you may encounter in your area. I could go on and on here but I don't think I can add much usefull information without more info from you.
By the way. May have to figure landscape and slopes beyond the building pad.
Helpful Member!  civilperson (Structural)
24 Sep 07 10:48
1.8 to 2.1 tonnes per cubic yard as a estimate.
Helpful Member!(2)  cvg (Civil/Environmental)
24 Sep 07 12:19
you should not estimate the amount of fill by weight.  better to do it by volume, "in place" which is a more common way to do it.
Helpful Member!  fattdad (Geotechnical)
24 Sep 07 13:16
typical weight of moist soil is 110 pounds per cubic foot (plus or minus 10 pcf).  There are 27 cubic feet in a cubic yard, so a cubic yard would weigh 2,970 pounds plus or minus 270 pounds.

Hope this helps in conjunction with the posts of others. . . . .

f-d

¡papá gordo ain’t no madre flaca!

alexcivil (Civil/Environmental) (OP)
24 Sep 07 15:25
thank you very much gentelman for your time and words.

we are going to use sand to build this foundation.  i do not have elevations nor plans.  

its just a foundation for a house that has to pass densities and i just wanted a way to estimate how much sand i am going to use for this pad.

what are the most common and accurate ways to estimate the amounts of sand for a building pad?  any formulas out there?

to what do they refer when people say a building pad has to be compacted to pass densities?

it is the density of wet sand?

onece again, DirtPusher, Civilperson, and cvg, THANK YOU VERY MUCH for your time and words.
cvg (Civil/Environmental)
24 Sep 07 20:20
your house foundation is arguably the most important thing.  you should have a plan and the permit will tell you the required density for the foundation.  you should consider whether sand is the most appropriate material for your foundation, especially if you are going to haul in the fill material.

I'm just guessing here, but it sounds like you may not be an engineer and probably not a civil.  Sounds like you may need to get an engineer involved or at least a contractor who can explain some of this to you directly.  You can go to city hall and ask the city engineer or county engineer and probably get free advice which will be better for you than what you probably get from this forum.  make sure you get a building permit.  In fact, better yet, require your contractor to get the permit and post a copy at the job site. it's required and will protect you from shoddy contracting work. (at least that is the theory...)
civilperson (Structural)
25 Sep 07 12:57
The fill proposed must extend beyond the limits of the foundation by at least the depth of the fill.  "Maximum dry density" is defined in ASTM D698 for a Standard Proctor.  A specification will say that compaction must achieve 95% or 98% of this "Maximum dry density".  A soils testing laboratory will test and certify the compaction of your fill.
alexcivil (Civil/Environmental) (OP)
25 Sep 07 16:08
fattdad, thank you for your answer.  very helpful. I am planning to calculate the amount of fill dirt by tonnes since i will be buying it by the tonne.  this will only be a rough estimate so that i can prepare a budget.

cvg, you are correct in guessing that i am not an engineer and certainly not a civil.  i apologize if i misled you in any way to think that i was one.  I will check with the city and ask for assistance there.  

i am going to hire a contractor to do the foundation but i thought it necessary to learn a little bit as to whats going to happen.  i have been reading this forum for several weeks now and have found very valuable infromation.  independent research has confirmed this.  the information i get from this forum is a very good beginning.

i am an actuary for a small investments firm who wants to be informed as to what to expect when i hire a contractor.  in addition to that, i have learned that earthwork (building pads jobs) seem to have a good profit margin.  i will consider a business of this nature as an aquisition target for our future investments.  

civilperson, thank you for replying on densities.  i am  clearer now.  also, it is good to know that i have to expand my foundation a couple of feet more on the sides.  i will take this into account to budget for the fill dirt.  

GENTLEMAN, I GREATLY APPRECIATE YOUR TIME AND HELP.  I UNDERSTAND HOW VALUABLE YOUR TIME IS.  ONCE AGAIN, THANK YOU.  I AM VERY GLAD TO SEE THIS IS A VERY FRIENDLY, PROFESSIONAL FORUM.   
cvg (Civil/Environmental)
25 Sep 07 19:36
again, I would warn not to buy material by the ton, but to pay for it by volume "in place and compacted to meet specifications"  Let the contractor worry about the tonnage
Dozerman56 (Civil/Environmental)
25 Sep 07 19:45
Alex:

I'm with fattdad, about 1.5 ton/cy. Having said that, if they're selling the material by the ton they certainly ought to be able to tell you the max dry density.

As far as the grading business making big profits, unless you're willing to start shepherding the operation at 5 AM and chase people until 8 PM, it won't happen.
alexcivil (Civil/Environmental) (OP)
26 Sep 07 12:49
cvg, how do i calculate the material volume "in place and compacted to meet specifications"?

is it just CY + some% to compensate for compaction?  If so, what percentage is it optimal for sand?

any input will be greatly appreciated, cvg.  thank you and all who particpated.
cvg (Civil/Environmental)
26 Sep 07 15:56
its not that complicated, just fill area times thickness. dirtpusher gave you a method to calculate it based on using a grid method.  But there are other methods such as average end area and pancake methods that also work.

you will set finish grades on your grading plan and the contractor has to build (the fill) to those grades.  He will continue to add material and compact in layers until he makes grade.  Once he is done you pay him based on the volume that was calculated (previously) based on your grading plan.  If he tries to charge you for an extra truckload of dirt (either by weight or by volume) he will need to prove that the in place volume changed for some reason.  If he has to add more material to account for shrinkage during compaction, that is his problem.  

the following site may provide a little more insight into earthwork estimating:
http://www.forester.net/gx_0409_taking.html
GrumpyG (Civil/Environmental)
1 Oct 07 9:05
As a rule of thumb, the 1.8-2.1 tons/CY seems to work.  I figure sand @ 2 tons/CY.
Multiply your neat/in-place fill volume by 1.15 for 15% compaction.  This will get you close. As Dozerman56 stated, your material supplier should know the weight of his materials.  

Also, you can ask for a copy of the delivery tickets from the excavation contractor, quarry or sand pit, verifying the quantity and cost. The site contractor is entitled to some profit or markup on this cost, unless you buy direct and assume the risk on the fill budget yourself.


TDAA (Geotechnical)
5 Oct 07 18:59
That will probably be the wettest / heaviest sand you ever see.  Pay by the yard, and don't buy water.
jtatlow (Mining)
23 Oct 07 23:53
FOR A ROUGH ESTIMATE ON DIRT USE 1.5

SQUARE FEET X DEPTH X WEIGHT(1.5) WILL GIVE YOU THE YARDAGE NEEDED FOR YOUR FILL.  THIS IS ROUGH BUT SHOUDL GET YOU CLOSE.

I.E. A 10 BY 10 PAD WITH 5 FEET OF FILL

100 X 5= 500 X 1.5 = 750 YARDS OF DIRT

PS-  AB/AC USE 2.

civilperson (Structural)
24 Oct 07 11:15
jtatlow,
 The formula submitted does not work.  Area times height equals volume, OK; but divide by 27 or multiply by 0.037037. Answer in cubic yards. Or multiply by 0.0704 for answer in Tonnes.

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