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#47358  04/04/04 11:22 PM
Re: How to estimate cubic yards of earth in excavation

Hall of Fame 2014
Lunker
Registered: 10/10/03
Posts: 871
Loc: St. Mary Parish, Louisiana


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#47362  04/05/04 10:17 AM
Re: How to estimate cubic yards of earth in excavation

Lunker
Registered: 05/28/03
Posts: 211

Treat the sloping sides as half of a solid rectangle and subtract their volumn from you 829 cu yds. ie, for 2:1 slope on sides :
Total yards : 829  (14 * 80 * 7)/27 = 539 cu yds
Note: the volumn of one sloping side is 1/2 of the (14 * 80 * 7)
If you slope the ends also, then : Total yards : 539  (14 * 40 * 7 )/27 + 4*Vc = 410 cu yds
where Vc is the inclusive yardage in the intersecting corners. This value can be approximated in your this case at about 4 cu yrds.

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#47364  04/05/04 12:29 PM
Re: How to estimate cubic yards of earth in excavation

Member
Registered: 08/21/03
Posts: 150
Loc: Southwestern Virginia

Dudley, I'm glad you pointed that out about the corners being irregular, I was worried someone would slip up on that. But Cecil I agree with Dudley, that should be close enough for a rough estimate. Plus most likely your corners will be rounded and not be the type of thing you get when two trangles intersect. Still a good estimate.

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#47365  04/05/04 01:11 PM
Re: How to estimate cubic yards of earth in excavation

Member
Registered: 04/18/02
Posts: 241
Loc: Dallas, TX

Cecil, if you have figured it out from the previous posts, good. But I thought that I would splain it another way.
The formula that they are referring to is Pythagoreans theorem. Look it up on the web for more answers.
But, I think that there is an easier way.
If you are doing a 1 to 1 drop, imagine a square 10 feet by 10 feet, if it had a 1 to 1 drop from one corner to the other, the bisecting line would cut the square exactly in half. So, knowing that a 10 X 10 square is 100 square feet, half would be 50 feet. This can easily be converted to cubic feet.
In the same way, a 2 to 1 drop would take a 20 X 10 box and cut it in half, so the 200 square feet would be bisected into two 100 square foot sections.
So in your application, if you dig down 7 feet, in a 1 to 1 scenario, it would take 7 horizontal feet to get down 7 vertical feet. (Pythagorenans theorem says that the length of that slope would be 9.89 feet.) A 7 X 7 slope, running 10 feet long would be 7 x 7 x 10 = 490 cubic feet, the half you are removing is 245 cubic feet of dirt.
In the 2 to 1 scenario, it would take 14 horizontal feet to get down 7 vertical feet. (Pythagorean says the slope is 15.65 feet long.) A 14 x 7 x 10 cube = 980 cubic feet, taking out half; you are moving 490 cubic feet of dirt. But the flat bottom portion of the pond will be smaller. (By 7 feet on each side) so you have to calculate in a savings there.
_________________________
Nick Smith

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#47367  05/03/04 12:26 AM
Re: How to estimate cubic yards of earth in excavation

Hall of Fame 2014
Lunker
Registered: 10/10/03
Posts: 871
Loc: St. Mary Parish, Louisiana

Cecil, I've been thinking about this problem for the past month, searching for a simpler approach to calculating excavated yardage involving square and rectangular ponds. How about this approach: Consider a point midway the sloped edges. At that point, the volume of dirt removed from the upper half will be very nearly the same as the volume of dirt remaining in the lower half of the sloped area. (because of the corners, the volumes won't be exactly equal, but in the interest of simplicity and because we're estimating, we'll ignore that minor difference). In the case of the 1:1 slope, with a seven foot pond depth, the dimensions of the pond at midslope would be seven feet less than the full pond dimensions (3 1/2ft on each side). A 40ft x 80ft pond would measure 33ft x 73ft at midslope. If we use those dimensions as the basis for our estimate, we would have 33ft x 73ft x 7ft = 16863cu ft. Dividing this figure by 27 cu ft/cu yd will give us 625 cu yd to be removed. With a 2:1 slope, the dimensions of the pond at midslope would be 14ft less than surface dimensions. 26ft x 66ft x 7ft = 12012cu ft. Dividing by 27 = 445cu yd. This approach seems accurate to me, Cecil, and certainly easier to work with than all that squaring stuff. I hope that Squeeky, Tritonvt, and Nick will offer their opinions. As a reminder, if you're loading into trucks, the volume of the dirt can increase by up to 1/3 because of decompaction.

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#47370  05/03/04 10:45 PM
Re: How to estimate cubic yards of earth in excavation

Lunker
Registered: 05/28/03
Posts: 211

Yes Dudley, you are actually computing the volumn of a rectangular solid whose sides extend through the midslope points of the excavation. Ignoring the geometry of the corners, You have come up with a niffty way to approximate the excavation volumn.

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#47371  05/06/04 02:10 PM
Re: How to estimate cubic yards of earth in excavation

Junior Member
Registered: 02/13/04
Posts: 2
Loc: N. Central Texas

Cecil, Here is a website I found with volume calculators. If they don't have what you need, an internet search should be able to find others. volume calculator

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