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# How to figure yards of topsoil ?

#1
10-14-13, 01:50 PM
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Join Date: Jun 2013
Location: USA
Posts: 116
How to figure yards of topsoil ?

I need to cover 2 areas, 2" deep:

1) 30' diameter circle

2) 10' X 20'

Thanks

Last edited by JimMcC; 10-14-13 at 02:08 PM.
#2
10-14-13, 02:46 PM
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Area of a circle = pi r² = 3.14 (15')² = 706.5'²
706.5'² x 2" depth = 117.75'³
117.75'³ x 1 yd³/27'³ = 4.36 yd³

10' x 20' x 1/6' = 33 1/3'³ = 1 1/4 yd³

I'd order 6 yards.

Last edited by stickshift; 10-15-13 at 12:21 PM. Reason: fixed error
#3
10-14-13, 02:50 PM
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First one...30' is 360" to keep measurements the same. Radius is 1/2 that or 180".

Calculating the Volume of a cylinder

Divide result by the cubic inches in a cubic yard. Cubic yd is 46656 cu in.

4.37 cubic yds needed

Second is 120" x 240" x 2" = 57600/ 46656= 1.23 cu yds needed

Total is just under 6 cu yds.

EDIT...Uh oh....one of us is off by about 2 cu yds on the circle. I've checked my using different measurements and I still get the same. Mitch, shouldn't the 2" in the second line actually be a fraction/decimal since 2" is 1/6th/.166 of a ft? Thats where our numbers diverge anyway. I may just not be understanding your math.

Call the Ref!

Last edited by Gunguy45; 10-14-13 at 03:19 PM.
#4
10-14-13, 08:36 PM
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Join Date: Jun 2013
Location: USA
Posts: 116
Thanks guys. Someone is wrong!!

#5
10-15-13, 06:48 AM
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Join Date: Feb 2006
Location: USA
Posts: 6,474
Cubic Yards

3.1417 x 15 x 15 = 707 sq ft ; 2 in deep = 707/6 = 118 cu ft/ 27 = 4.37 cu yds

10 x 20 = 200 sq ft/6 = 33.3 cu ft/27 = 1.23 cu yd

4.37 + 1.23 = 5.6 cu yd

Is this a tie breaker?

#6
10-15-13, 07:22 AM
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For landscaping you might want to order about 25% more than your calculation to allow for compaction.

#7
10-15-13, 12:18 PM
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Hmm... we agree on the rectangle, let me do the math on the circle again.

#8
10-15-13, 12:21 PM
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Found an error - 775/6 is not 177; my second line should end 117.75'³. This then leads to a total of 4.36 yd³, which matches Vic's total.

Sorry about that. I've updated my original post so no one gets confused by it later.

#9
10-17-13, 11:20 AM
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Join Date: Jun 2013
Location: USA
Posts: 116
When raking the topsoil before seeding, do I want the topsoil height slightly higher than the current grade to allow for settling, or do I make it the same height? If higher, how much higher? Thanks.

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