Spill Containment Volume Calculator: SPCC Volume Prompts

How It Works

1. Enter Container Data

   Input each container capacity and its footprint area inside the containment. The calculator identifies the largest entered container and the aggregate entered volume.

2. Choose a Volume Basis

   Use the largest-container prompt for a federal SPCC-style arithmetic calculator, or the aggregate prompt where the project basis requires stricter local review.

3. Enter Rainfall, Freeboard, and Margin

   Enter the approved rainfall depth, freeboard, and any capacity factor required by a state, owner, insurer, fire code, or AHJ. The default capacity factor is 100 percent.

4. Review Source Warnings

   Use the screened berm height only as a planning prompt, then verify SPCC applicability, site geometry, imperviousness, drainage, inspection, and qualified review requirements.

Built For

• Environmental managers screening containment volume before SPCC plan or consultant review
• Plant engineers comparing largest-container and aggregate local-margin prompts for a tank area
• Facility teams documenting the assumptions that need qualified SPCC, civil, structural, or AHJ review
• Fuel storage operators estimating how entered rainfall affects preliminary containment volume
• Agricultural or construction teams checking whether local containment assumptions need escalation before purchase or layout decisions
• Environmental consultants checking simple rectangular containment arithmetic before using project-specific models or drawings

Features & Capabilities

Largest-Container Prompt

Screens the selected container basis without silently adding a 110 percent margin. Enter a local capacity factor only when the project basis requires it.

Precipitation Volume

Adds the user-entered rainfall depth over the containment footprint. The app does not perform a NOAA lookup or approve the storm event.

Footprint Area Deduction

Subtracts entered tank footprint areas from the rectangular containment footprint. Piping, pads, slopes, sumps, and appurtenances remain source gaps.

Berm Height Prompt

Calculates a screened liquid height plus entered freeboard from the simplified rectangular geometry.

Existing Berm Screen

Compares an entered existing height against the entered prompt and reports shortfall or surplus without claiming compliance approval.

PDF Export

Export the arithmetic screen with source warnings and residual gaps for qualified review.

Assumptions

• Largest-container prompt uses the largest entered container volume; aggregate prompt uses the sum of entered container volumes
• Capacity factor defaults to 100 percent and is user-entered for local/state/owner/insurer/AHJ margins such as 110 percent
• Precipitation allowance uses the user-entered rainfall depth; the app does not perform a NOAA PFDS lookup
• Entered tank footprint areas are subtracted from rectangular containment area; other displacement and geometry details remain unresolved
• Freeboard is user-entered and added to calculated liquid height
• SPCC applicability, oil definition, qualifying facility tier, certification, inspections, and state/local requirements are not determined by this app

Limitations

• Does not determine whether your facility meets the SPCC threshold - consult EPA 40 CFR 112.1 applicability criteria
• Does not treat 110 percent as a universal federal SPCC requirement
• State, local, owner, insurer, fire-code, or AHJ rules may require a larger factor or aggregate-volume basis
• Does not account for piping, transfer hose, pump, or manifold failures outside the bermed area - these may require separate containment
• Precipitation accumulation from storms smaller than the design event can reduce available containment if rainwater is not drained regularly
• Does not evaluate containment material compatibility with the stored product (chemical resistance of liners, coatings, and concrete)
• Does not approve freeboard, stormwater discharge, drain-valve procedure, inspection interval, or emergency response assumptions
• Underground storage tank (UST) containment requirements under 40 CFR 280 are separate from SPCC and are not addressed

References

• eCFR 40 CFR Part 112 - Oil Pollution Prevention and SPCC secondary-containment sections
• EPA SPCC secondary containment FAQ and applicability guidance
• NOAA PFDS / Atlas precipitation-frequency data for approved site storm-depth review
• NIST SP 811 - unit conversion and SI usage reference
• Project-specific state, local, fire-code, building-code, stormwater, insurer, owner, and AHJ requirements

Frequently Asked Questions