$5.$ a $40-$ton crane with a $3-$cubic$-$yard clamshell bucket to excavate the sand out of the bottom of a river channel to be used in a concrete plant. The fill factor of dredging sand with the bucket is $1\mathrm{.}20.$ The contractor will use dump trucks to haul the sand off$-$site to the concrete plant and estimates that the clamshell will operate at an efficiency of about $52$ minutes per hour. The estimated cycle time of the clamshell is $25$ seconds. Please calculate what the estimated production rate is for the clamshell in cubic yards per hour.