Diking requirements are based on size, not whether you're a farmer or dealer, notes Matt Pearson, fertilizer administrator for the Office of Indiana State Chemist. The two key numbers are 2,500 gallons and 7,500 gallons.
Tanks larger than 2,500 gallon capacity are regulated, even if you only have one of them. If you have more than 7,500 gallons total capacity at your facility, you are also regulated. Anything larger than a 55-gallon drum adds to the total.

Here's what this means, Pearson says. A farmer with three 2,500 gallon tanks and nothing else legally does not have to have a dike. A farmer with 8,000 gallons storage does. This could be four 2,000 gallon tanks. A farmer with one 3,000 gallon tank also falls under the regulations.
Once you fall into the regulated category, you must have a dike and a loading pad, Pearson says. Mini-bulks of micronutrients larger than 55 gallons must be in secondary containment as well.
You don't need a permit from the Office of Indiana State Chemist to build a dike. You may need a building permit from your local government. There is no requirement to call the Office of Indiana State Chemist before building. However Pearson says most call either him or Fred Whitford, coordinator of Purdue Pesticide programs, before they build, and he advises them to do so.
However, you are required to register the facility with the Office of Indiana State Chemist. Pearson wants to know your location, and how much you are storing. There is no fee to register.
There is one advantage to complying with the rules. Since the mid-'90s, there are deductions in assessed value for property tax purposes for improvements installed to comply with the containment rules.
If you're wondering where to start, Pearson has a simple kit of information he can send you. Reach him at 765-494-1547 or email [email protected].