A client has approached you about building a rectangular dam to hold a specific volume of water of

$9000$ m$3$

$.$ The client has limited room and proposes a dam base of $30$m x $40$m and $40$m x $60$m at the

top. If the desired batter slopes at corners for the dam is $2$:$1($rise:run$),$ calculate the depth and

volume of the dam $($fully document all working$).$