Question $1-$ Mine Surveying $($Volumes Calculations & Leveling$)$

$1\mathrm{.}1$ The plan and elevation of an excavation is shown below. Calculate the volume excavated from the pit.

Hints: The excavation can be split in prisms for which volumes need to be calculated and summed up to the total volume. A $2$:$1_{?}$ side slope indicates that for every horizontal distance of $2m,$ the corresponding vertical distance is $1m,$ or slope percent $=50\%.$

$[15]$