Secondary containment calculator
- Rule: capacity ≥ the greater of 10% of all containers or the largest container
- Total volume: 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 + 55 = 1,100 gal
- 10% of the total: 0.10 × 1,100 = 110 gal
- Largest container: 55 gal
- Take the greater: 10% of the total
- Answer: at least 110 gal
Formulas and sources
- RCRA containers: capacity ≥ max(0.10 × total volume, largest container)
- SPCC bulk storage: capacity ≥ largest container + rain freeboard
- Rain freeboard (gal) = (rain in ÷ 12) × dike area ft² × 7.48052
The formula comes from
40 CFR 264.175(b)(3)(opens ecfr.gov in a new tab)“The containment system must have sufficient capacity to contain 10% of the volume of containers or the volume of the largest container, whichever is greater. Containers that do not contain free liquids need not be considered in this determination;”
The formula comes from
40 CFR 112.8(c)(2)(opens ecfr.gov in a new tab)“Construct all bulk storage tank installations (except mobile refuelers and other non-transportation-related tank trucks) so that you provide a secondary means of containment for the entire capacity of the largest single container and sufficient freeboard to contain precipitation.”
Formulas and calculators on the BCSP exams
- BCSP gives you no formula sheet, and you can't bring one.
- When a question needs a formula, the formula is written into the question, unless the question is testing whether you know that formula.
- You get an on-screen calculator that works like the TI-30XS, plus a whiteboard. You can't bring your own calculator.
- On the ASP, Mathematical Calculations is its own domain, worth 10% of the exam (ASP11 blueprint).
BCSP on formulas
BCSP, What to Expect When Sitting for a BCSP Exam (item 7)(opens bcsp.org in a new tab)“For any question requiring a mathematical formula, the formula will be included within the exam question (unless the question is specifically testing your knowledge of a formula). You will not be provided or permitted to bring a formula sheet.”
BCSP on calculators
BCSP, What to Expect When Sitting for a BCSP Exam (item 6)(opens bcsp.org in a new tab)“You will be provided an on-screen calculator, emulating the TI-30XS scientific calculator. You will also have access to a white board and dry erase marker. The testing center will not provide a physical calculator or permit candidates to bring their own.”
FAQ
How much secondary containment do hazardous waste containers need?
Under 40 CFR 264.175(b)(3), the greater of 10% of the total volume of the containers or the volume of the largest container. Containers without free liquids aren't counted. For 20 drums of 55 gal: 10% of 1,100 is 110 gal, which beats 55 gal, so 110 gal.
How much containment does an oil tank need under SPCC?
Under 40 CFR 112.8(c)(2), enough for the entire capacity of the largest single container plus sufficient freeboard to contain precipitation.
How much rain should freeboard hold?
112.8(c)(2) says "sufficient freeboard" and doesn't set a number. Enter the rain depth your design uses. Covered or indoor storage may not need any.
How do I turn cubic feet into gallons?
Multiply by 7.48052. A U.S. gallon is 231 cubic inches and a cubic foot is 1,728, so 1,728 ÷ 231 = 7.48052 gallons per cubic foot.
This tool is for study and estimates. It doesn't replace your SPCC plan, a professional engineer's certification or state rules, which can be stricter.