



 
Hi Mark. If I understand correctly, you are looking for the wedgeshaped volume in this diagram: Where it is actually 75 ft long, 3 feet horizontally and between 6 and 2 inches deep. Thus, the cross section looks like this: This shape is a trapezoid (in the UK it is called a trapezium). The area of this trapezoid times the length of the trench will be the volume of the fill you need. The area of a trapezoid is simply the distance between the parallel sides times the midpoint distance. Thus, in your case, it is 36 inches times 4 inches. So the volume of your wedge is this: So that's how much dirt you'll need to fill the trench. Stephen La Rocque. >  


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