What considerations do I need to specify that the bottom of the tank have a slope.

The TANK software doesn't consider sloped bottoms.

Thanks Richard,
Can somebody who has an experience in the field do a favor to answer my question.

Seems to be almost too much of an open question: You will need to know the reason for the slope (cleaning and flushing between different chemicals or sources, draining naturally to a low point, draining to a mixer, etc.)

Based on why you need the slope, then from temperature and viscosity and degree of cleanliness (percent residue allowed by the customer) you figure out the amount of slope needed and direction of the slope: drain in the middle, drain at one point, drain from a "pit" around the edge of the tank ... From that, figure out how you are going to support the sloped floor: a sloped reinfiorced slab underneath a simple metal floor I'd assume is cheapest.

About 10 degree