Changing the weight of cubic yards

Question

A pipe trench is 72’ long 2’6” wise and has an average depth of 4’3” how many cubic yards of soil were removed? If the soil weighs 2700lbs per cubic yard how many tons would that be?

Answer 1

Hi Chris.

 

In order to use the fact that soil weights 2700 pounds per cubic yard, means we need all of the measurements to be in yards.

 

1 yard = 36 inches = 3 feet.

 

So 72 feet long  (divide it by 3 feet per yard) is 24 yards long.

 

2'6" is 2 feet (* 12 inches per foot) + 6 inches = 24 inches + 6 inches = 30 inches wide.    And 30 inches wide (divided b y 36 inches per yard) = 0.8333 yards wide

 

4'3" deep is 4*12 + 3 = 48 + 3 = 51 inches deep (divided by 36 inches per yard) = 1.417 yards deep.

 

Now we just need length * width * depth to get how many cubic yards.

 

Volume is 24 yards * 0.8333 yards * 1.417 yards = 26.25 cubic yards.  

 

Soil weighs 2700 pounds per cubic yard, so multiply 2700 pounds per cubic yard * 26.25 cubic yards = 70,875 pounds.

 

A ton is 2000 pounds, so divide this number (70,875 pounds)  by 2000, and find the number of tons.

 

70,875/2000 = 35.4375 tons  (and that is the answer!)