The Spill Prevention, Control, and Countermeasure (SPCC) rule under 40 CFR Part 112 can apply to facilities that store, handle, transfer, distribute, use, or consume oil and could reasonably be expected to discharge oil to navigable waters or adjoining shorelines. EPA applicability questions include non-transportation status, oil storage activity, discharge expectation, aggregate aboveground capacity greater than 1,320 gallons, buried capacity greater than 42,000 gallons, and container exclusions.
This guide covers containment math and review boundaries. It is not a legal determination, SPCC plan, PE certification, state/local compliance checklist, or approval to construct containment. Use the app to work out a rectangular-volume estimate, then reconcile the source gaps with the current rule, EPA guidance, site facts, and qualified review.
SPCC Applicability Is a Source Check
EPA asks whether the facility is non-transportation-related, handles oil, could reasonably discharge oil in harmful quantities to navigable waters or adjoining shorelines, and exceeds the applicable storage-capacity thresholds after exclusions. The aboveground threshold is greater than 1,320 gallons; containers less than 55 gallons and some other categories are excluded from that count.
Capacity generally means container storage capacity, not the amount currently in the container. Underground tanks, wastewater-treatment containers, motive-power containers, permanently closed containers, farm-specific paths, qualified facilities, and state/local overlays can change the review. Do not use a volume worksheet alone to decide whether a facility is regulated.
The app warns when entered aggregate aboveground capacity exceeds 1,320 gallons, but that warning is only an escalation prompt. It does not decide oil definition, discharge expectation, container exclusions, qualified facility status, or certification path.
• Non-transportation status
• Oil storage/handling/use activity
• Reasonable discharge expectation
• Aboveground capacity >1,320 gallons after exclusions
• Buried capacity >42,000 gallons after exclusions
• Current EPA rule, state/local overlays, and qualified review
Spill Containment Volume Calculator
Calculate required secondary containment volume per EPA SPCC regulations with precipitation allowance.
Secondary Containment Volume Basis
For bulk storage container installations, EPA/eCFR language points to secondary containment for the entire capacity of the largest single container and sufficient freeboard to contain precipitation. That is not the same as saying every federal SPCC screen must silently use 110 percent of the largest container.
A 110 percent factor, 125 percent factor, or aggregate-volume basis may still be required by a state rule, local code, owner standard, insurer, fire marshal, permit, or AHJ. The app handles that by exposing a capacity-factor field and an aggregate-volume option, keeping the project basis visible.
The simplified screen uses entered container volumes, entered footprint areas, rectangular containment dimensions, entered rainfall, and entered freeboard. Actual designs may need to model sloped floors, low points, sumps, drain valves, supports, pumps, piping, wall geometry, tank foundations, liners, cracks, and other displacement or loss-of-capacity details.
Liquid basis = selected container basis × entered capacity factor
Precipitation = L × W × entered rainfall depth
Net area = L × W - entered tank footprint areas
Height prompt = total required volume / net area + entered freeboard
Rainfall, Freeboard, and Drainage
The app does not look up NOAA rainfall or choose the required storm event. Replace the placeholder rainfall depth with the approved site value from NOAA PFDS/Atlas data, a plan basis, local drainage criteria, or the authority having jurisdiction.
Accumulated stormwater inside containment can reduce available capacity before a design storm occurs. Drainage procedure, valve type, inspection before discharge, treatment, permits, records, and sheen response are compliance and operational controls that a volume screen cannot approve.
Freeboard is user-entered because the accepted value can come from rule language, plan history, local criteria, owner standards, or engineer judgment. Treat zero or unusually small freeboard as a review warning unless the project basis clearly supports it.
Use an approved site-specific storm depth and keep the source in the project record. The app only multiplies the depth you enter by the containment footprint.
Construction and Qualified Review Gaps
Secondary containment performance depends on more than volume. Wall and floor imperviousness, liner/coating compatibility, concrete joints, penetrations, hydrostatic load, settlement, erosion, chemical compatibility, valves, sumps, pumps, and access/egress all need project-specific review.
Inspections, integrity testing, plan amendments, records, employee training, spill response, and certification path are governed by the current rule, EPA guidance, state/local requirements, and facility facts. The app exports source warnings and residual gaps so the arithmetic output is not mistaken for compliance approval.
Before relying on a containment prompt, reconcile the current regulation, EPA guidance, NOAA or local rainfall source, owner standards, insurer/fire-code requirements, drawings, field measurements, and qualified environmental, civil/structural, legal, AHJ/regulator, or PE review.
• SPCC applicability decision
• PE or self-certification path
• State/local or fire-code approval
• Impervious containment design
• Drainage/discharge procedure approval
• Inspection or recordkeeping program