Floors of Class 2 and Class 3 impounding systems must, to the extent feasible— (a) Slope away from the component or item impounded and to a sump basin installed under § 193.2171; (b) Slope away from the nearest adjacent component; (c) Drain surface waters from the floor at rates based on a storm of 10-year frequency and 1-hour duration and other natural water sources; and (d) Be designed to minimize the wetted floor area.