Depending on the type of tank that is required, the tank will be designed according to ASCE 7, AWWA D100 or API-650 standards.
Depending on site soil conditions, tank foundation systems varies from a simple ring beam or mat slab to pile or geopier system.
Can you provide more information about this needed tank? One of the first items on the list would be a soils report-- Your engineer than will recommend
the proper type of foundation based on tank design and customer requirements.
You are asking very basic questions that suggests an experience level that is not going to result in an efficient use of your time, or those on this forum. Basic engineering: determine the loads, discover the soil bearing capacity and characteristics, design the foundation. API 650 slope is 1 inch in 120 inches cone up but many others are used with great success, depending on many many factors. Insulation depends on the thermal properties of the stored product and the foundation as well as the acceptable operating temperature range. There is lots more to know and learn, It's going to be tough for you to do that in this medium. Good luck!
