I'm betting there is a good formula out there to estimate the volume of a pile if you have a measurement of its circumference, the height, and the angle of the slope?? I think I missed that day of algebra or trigonometry, or maybe the principal had me in his office? Anyway, a new client just built a 2 acre building and most of the excavation from the project is sitting next to the building & needs to be removed. So I was trying to figure out the best way to get an idea of just how much it is. Thanks for any help with that.
Well if you could figure out what kinf of hole they dug length x width x height it would be like any other job that you must figure that is how I would look at it unless they piled dirt from every where at that spot and not only just from the foundation oh don't forget the fluff factor to. roughly 20%
What you have is a “Cone†of dirt. The volume of a cone is 1/3(Area of Base)(height) = 1/3 ð r2 h Example: Pile 20 feet in diameter 8’ high, would have a radius of 10’ Remember that ð or Pie roughly equals 3.1416 So the volume would be 3.1416 x 10squared x 8 and dived all the previous step by 3 for the 1/3 part. = 2531.3 divided by 3 = 837.76 cubic feet. 837.76 cubic feet divided by 27 = 31.03 cubic yards
Estimating Volume of a material pile There is a couple of ways I approach it. Depends on how exact you want to be. Quick and dirty way: Treat it like a cone. Volume = (pi x radius(squared) x height) / 3 or Volume (cu.ft.) = 0.2618 x Diameter(squared) x height I then 'fudge' for the shape characteristics. If you want to get more exact (take into account that sides are not same, compaction of material, etc.) we would need to break out some calculus and break the pile into segments. I have yet to encounter the need to do that on a construction site. That's your call. There are probably some programs out there that are more exact.
Now I know why I should have listened more in math class. It look like a foreign language to me.
SO, did you know the cone formula off the top of your head, or did you have to look it up ?
I knew the cone formula in my head. The volume formula is from my notebook. I keep a running set of frequently used formulas with me.
Impressive !
Had to go to the book!
I believe they broke ground around 2 years ago, its around 80,000 sq ft of building, there 2 drainage basins, and 2 acres of roads & parking lots. So estimating off of what hole they dug for the foundation measurements method wasn't going to work in this case. Plus I think some of it has been removed already. Thanks for the formula, I actually recall that now through the fog in my brain, so maybe I was there that day afterall I can look at the small piles of stuff I usually deal with and get a rough estimate by eye. But this pile is as tall as the 2-3 story building, and maybe 100' or more in diameter, so I had no idea what to estimate looking up at it lol. Now I can go take some measurements & get a rough idea. What I don't understand is why removing it wasn't included in the construction process? I'll have to ask them that when I see them again.
Estimating the cone volume is correct. If you are dealing with the measurements from the hole from which the dirt was removed, you must also allow for the swell factor. Dirt which is dug swells and if you forget to allow for the swell you will have more dirt than you calculated. To determine swell, clay soils swell by a factor of 1.12 to 1.17. If you dig a 100 cubic yard hole, it will take 117 yards of truck space to truck it away. This really gets to be critical with topsoils and muck which can swell as much as 1.5 to 1.65. There are some nice software estimating packages which allow you to trace the lines on a set of plans and be able to calculate all quantities to 3 decimal places. In a situation like you have, you could just enter the cone measurements and have really accurate information for your bid. There is a link on my website for estimating software if you'd care to look. I am convinced that more contractors get hurt and go out of business bidding volume than any other part of the services we bid. Remember in the third grade, the teacher took out several dissimilar glasses and proved you can't tell which glass will fill the other, she was telling you that we, as a species, are not that good at estimating volume!
BRL since you did not excavate the building and do all the cutting of fill would it not be easier and safer to give a per load price. this way you get wat you deserve and the customer does not get overbilled.
Even if you priced per load it would be nice to know the estimate of material so that you and the customer can judge time, proper equipment, disposal and cost.
I was told to figure out how much material you will have after it is excavated is for example if you figure you dug a hole that when measured 1k cubic feet of meterial just add 20% for the fluff factor.
20% fluff may not be e-nuff for all de stuff adding a 20% fluff factor is a good rule of thumb for heavy clay. It is very close to multiplying by 1.17 which is what I suggested earlier, so we agree about clay. If you attempt to apply this 20% rule to fluffier soils like loam, sandy loam, or muck, you will produce an estimate that will be off as much as 35%, and you may loose a very important part of your anatomy. Each soil type fluffs ( swells at break out) at a different rate. That is why most better quality plans tell you exactly what types of soils exist on your site, and where. Civil engineering charts exist which tell you the exact amount of swell to expect for each soil type. The larger sites you work, the more critical this becomes. ( miss a small site bit by 5% and laugh about it at the bar tonight. miss a large site by 5% and maybe go out of business) When larger companies bid, they use a digital pen to trace all the lines on the plans while telling the computer what information is existing and proposed. The computer then turns the information into digital information and is able to make precise calculations on every volume calculation on your site. Imagine how much more accurate and safe your bid would be if you knew exactly what every volume was. The computer estimating programs also give you the ability to "balance a site." [ figure out what evevation to build your site so no dirt is imported or exported] Many surveying companies do not have the math skills to calculate a balanced site in this lifetime so an arbitrary elevation is chosen. If you can offer a balanced site alternative to the plans, you often become the only bidder in a new proposal which saves the developer money and seperates you from the other bidders. Another big advantage area of computer bids is in roadbuilding. The computer programs allow you to insert dimensions of the specific road profile into the computer and trace the centerline of the road. The computer then does all the cut and fill calculations and gives you an average materials move list, like: move 5670 cu yds an average of 516 feet. Most non-computerized bids are the product of 1. an educated guess, plus 2. the addition of a fudge factor, and 3. the prayer for a profit. When you know exactly how much dirt will move and what kind of dirt it is, you can bid much closer without fear of hurting yourself. Since most of us can't run out and drop $6 to 14K on a computer estimating program, and many of us don't have an honors math degree to make the calculations ourselves, it is often best to change the rules, if possible, and convert the bid to unit and hourly pricing. Some bids are pre-funding and may be building their budget to apply for project funding. Unit and hourly won't work if they are going to the bank for funding in most cases. Most out-of-pocket type projects may work well with unit and hourly pricing and since this type project often comes without plans, unit and hourly pricing is a good way to protect yourself and insure your profit. (someone mentioned this earlier but it seemed like it fit in here too.) This approach keeps poor math skills from hurting you, too. Some demolition jobs are good candidates for unit and hourly, too, because of the difficulty of bidding debris volumes, and small blasting and rock removal jobs fall into this category, too. Quest and HeavyBid are two of many project estimating softwares. Happy Estimating
NAC et al, This thread was from 2004, the pile is gone now. They got lucky & found someone who needed fill & so didn't have to pay to have it hauled. Now I'm not sure who paid for replacing the curbs, pavement & sidewalks that got destroyed during the process though But if I had done it, the price would have been per load plus excavator for loading. As Ct18 points out, even so, it is nice to give the client a rough idea of how many loads are there etc. so they have an idea of what they will need to pay.
As long as the topic of "swell factors" is on the table... If material is already in a pile, then it has already been fluffed up, so to speak. Depending on how it was stacked (it might have simply been cast on the pile from an excavator bucket, or dumped from trucks and pushed up by a tracked loader or dozer, for example), it will have been recompacted to some extent, but probably not to its original density. Is there any well defined swell factor that can be applied to (for lack of a more scientific term), "loosley compacted" material? Or are we back to the realm of educated guesswork again?
Uh-oh, I made a point As was also said, estimating volume is perhaps the hardest part of the business. I had a topsoil job that ended up taking 40% more then I originally told the customer. (Some of this was there choice to do more work.) I had told the customer though, what the price per yard was and what I thought the min. was. I told them to excpect to use more and when it was needed to do the job right they had no problem with it.