Calculate the Amount of Import or Export

For the project site shown in Figure, the amount of import or export to bring the entire site to elevation 90-ft is most nearly:

Solution:

By inspection, the project has a combination of areas where there are imports and exports to bring the entire site to elevation 90-ft.Further, the multiple choices given for the answer should be analyzed.There is a spread of approximately 20% among the choices which suggests a broad perspective analysis to determine the solution. 

The figures to the right illustrate a broad based analysis.  Assume one grid:

  Existing          90.50-ft

  Proposed        90.00-ft

  Cut                 0.50-ft

  Total Export = [150-ft x 300-ft x 0.50-ft] ÷ 27ft³/yd³ = 833-yd³