This calculator requires the use of Javascript enabled and capable browsers. It is to determine the volume of a bund structure. For those of you that do NOT know what a bund is (as I didn't until I researched this request), a bund is a reservoir-like structure, of regular or irregular shape, to hold the contents of another structure, such as an above ground tank of liquid, in the event of the tank's failure. This calculator does not approach the construction methods of the bund, only the volume requirements. There are basic environmental disaster prevention requirements for bunds used on applications such as farms for above ground storage of fertilizer, pesticides or petroleum products. The first requirements calculation method implies that if the bund is for only one tank structure, the bund volume must be at least 110% of the tank's potential ; if used for multiple tanks, it must be at least 125% of the total potential volume of all the tanks. The alternative requirements calculation method implies that if the bund is for only one tank structure, the single tank volume potential must be no greater than 90% of the bund; if used for multiple tanks, the total potential volume of all the tanks must be no greater than 75% of the volume of the bund. The methods sound similar but the requirement values calculated are entirely different. In this calculator, the bund is assumed to be irregular but it could be the surface shape of a square, a rectangle, a triangle, all with depth (examples might be a cube, rectangular prism or triangular prism, or an irregular shaped of those combinations), volume capable, structure. If it is a square or rectangle surface shape, enter the depth, length and width dimensions in the Rectangle section only. If it is an irregular bund, segment it into the surface shape of a rectangle and up to four triangles. They do NOT need to be right triangles. Enter the consistent depth used in all the calculations. Enter the height and base of all of the triangles in each Triangle section required (up to 4), and length and width dimensions in the Rectangle section. If you only have one triangle and a rectangle, only use those fields. In triangles, the height is measured in a perpendicular from the highest point to the base. The depth is from the surface of the structure to the flooring and is consistent in all calculations. All entries should be numeric. The answers are returned as cubic unit numbers, based on your entries. Enjoy! NOTE!!! If this bund is being used for environmental protection, be sure to check with local authorities regarding volume requirements, materials requirements and other guidelines and regulations.