How EPA Sets Threshold Planning Quantities (TPQ) Under EPCRA

Under the Emergency Planning and Community Right-to-Know Act, a Threshold Planning Quantity is the chemical-specific inventory level that pulls a facility into local emergency planning. Each Extremely Hazardous Substance on EPA’s list carries its own TPQ, and the moment your on-site inventory of that chemical reaches or exceeds the number, a 60-day clock starts running for notifying state and local planners.¹ The threshold planning quantity under EPCRA is not a safe-storage limit or a spill-reporting cutoff; it is a planning trigger, and it works differently from the reportable quantities and Tier II thresholds that sit alongside it.

How EPA Sets the Number

TPQs are assigned through a ranking system built on an Index Value that divides a chemical’s Level of Concern (its toxicity measure) by a volatility factor reflecting how readily the substance becomes airborne. A gas gets a volatility factor of 1, so the full toxicity score drives its ranking. A liquid’s factor depends on molecular weight and boiling point, meaning a quick-evaporating liquid scores close to a gas while a thick, slow-evaporating one scores much lower.²

The Level of Concern itself comes from NIOSH’s Immediately Dangerous to Life and Health values where those exist, and from acute animal toxicity data where they don’t. The most dangerous substances on the list carry a TPQ as low as 1 pound. Nickel carbonyl is one example. Less toxic or less volatile chemicals go as high as 10,000 pounds.³

EPA has statutory authority to revise the list and its thresholds, weighing toxicity, reactivity, volatility, dispersability, combustibility, and flammability.⁴

Finding Your Chemical on the EHS List

Appendix A of 40 CFR Part 355 lists more than 300 Extremely Hazardous Substances, each with its assigned TPQ. Chlorine gas, ammonia, and hydrogen fluoride are on it. Sulfuric acid is on it. So are hundreds of less familiar compounds.³

The practical starting point is EPA’s Consolidated List of Lists, which cross-references chemicals covered under EPCRA, CERCLA, the Clean Air Act, and the Clean Water Act. For each chemical it shows the TPQ, the reportable quantity for spill reporting, and which other statutes apply. EPA cautions that the document is a reference tool, not a substitute for the regulation itself.⁵

Reading a Dual TPQ Like 500/10,000

Many solids on the EHS list show two numbers separated by a slash. The lower number applies only when the solid is in a form that makes it easier to inhale or disperse. The higher number, always 10,000 pounds, applies when the same solid sits in a less dangerous physical state.

The lower TPQ applies if the solid meets any of these conditions:

Powder form with particle size less than 100 microns
Dissolved in a liquid
Molten (heated past its melting point)
Rated 2, 3, or 4 on the NFPA reactivity scale

If none of those apply, for instance when the solid is stored as large pellets or intact chunks, the TPQ defaults to 10,000 pounds.³

Counting What You Have

The quantity that matters is the maximum amount of the EHS present at any single point in time, not annual throughput or an average. Add up the total weight across every container, tank, process unit, and transport vessel on site.

When the EHS is part of a mixture, count only the weight of the hazardous component: multiply the mixture’s total weight by the EHS’s concentration by weight. A 2,000-pound tank of a solution that is 30% sulfuric acid contributes 600 pounds of sulfuric acid toward the threshold.³

Lead-Acid Batteries

Battery banks are a common trap. Sulfuric acid is an EHS, and EPA requires facilities to aggregate the sulfuric acid across every lead-acid battery on site. Sulfuric acid’s TPQ is 1,000 pounds. For Tier II purposes the threshold drops to 500 pounds or the TPQ, whichever is lower, so any facility carrying 500 pounds or more of sulfuric acid across its battery inventory meets the Tier II threshold. The lead inside those batteries does not need to be aggregated unless the facility chooses to report it.⁶

The One Exemption to Know About

EPCRA Section 327 exempts substances that are in transit or stored incident to transportation under active shipping papers. Chemicals moving through your site on their way somewhere else don’t count toward the TPQ. Chemicals that have arrived at their destination or entered a production process do. The exemption also does not cover emergency release notifications under Section 304; if a spill happens during transit at your facility, you still have to report it.⁷

There are no other Section 302 exemptions. Factories, water treatment plants, and farms are all covered if they hold an EHS at or above its TPQ.⁸

What You Have to Do Within 60 Days

Once your inventory reaches or exceeds the TPQ, the owner or operator must notify the State Emergency Response Commission and the Local Emergency Planning Committee within 60 days. The same 60-day clock restarts if EPA revises the EHS list and a chemical already on your shelves appears at or above its newly assigned TPQ.¹

The notification identifies the facility, lists the covered substances, and provides contact information. Within the same 60-day window the facility must designate a facility emergency coordinator to participate in local planning and report that person’s name to the LEPC.⁹ If the LEPC later requests information needed to build or update the local emergency plan, the facility must supply it within the committee’s timeframe.

The obligation to keep planners informed is ongoing. If the facility switches to a different EHS or significantly increases storage, notify the LEPC. The statute doesn’t fix a deadline for every possible change, but silence is not the safe path.

How the TPQ Fits With Release Reporting and Tier II

The TPQ triggers planning. It is not the same number that triggers a spill call, and it is not the same number that triggers your annual inventory filing.

If an EHS or CERCLA hazardous substance is actually released at or above its reportable quantity, Section 304 requires immediate notification to the SERC and to the LEPC for any area likely to be affected, followed by a written report as soon as practicable. For CERCLA substances the facility must also call the National Response Center at 1-800-424-8802.¹⁰

Sections 311 and 312 layer on annual reporting for any chemical requiring an OSHA Safety Data Sheet, not just EHSs. The Tier II inventory form is due every March 1 for the prior calendar year. Reporting thresholds are:

Extremely Hazardous Substances: 500 pounds or the TPQ, whichever is lower
All other hazardous chemicals: 10,000 pounds
Gasoline at a retail station (underground tanks in UST compliance): 75,000 gallons
Diesel fuel at a retail station (underground tanks in UST compliance): 100,000 gallons

¹¹

Penalties for Missing the Planning Notification

Congress set the base civil penalty for Section 302 emergency planning violations at $25,000 per day. After mandatory inflation adjustments it now stands at $71,545 per day for each day the violation continues.¹² Release notification violations under Section 304 carry the same $71,545-per-day figure on a first offense and $214,637 per day for a second or subsequent violation.¹³

Criminal exposure attaches to release notification failures, not to missed planning notifications. Knowingly and willfully failing to report an emergency release under Section 304 carries up to $25,000 in fines and two years in prison on a first conviction, doubling to $50,000 and five years on a second.¹³

Tier II violations under Sections 311 and 312 run $71,545 per day for first violations, with a separate $28,619-per-day figure for certain trade secret violations.¹² Because each penalty runs per day, an overdue filing can build a large liability quietly before anyone flags it.

1
Office of the Law Revision Counsel. 42 U.S.C. Chapter 116 – Emergency Planning and Community Right-to-Know
2
Regulations.gov. Assigning Threshold Planning Quantities for Extremely Hazardous Substances
3
eCFR. 40 CFR Part 355 – Emergency Planning and Notification
4
Office of the Law Revision Counsel. 42 U.S.C. 11002 – Substances and Facilities Covered and Notification
5
U.S. Environmental Protection Agency. Consolidated List of Lists
6
U.S. Environmental Protection Agency. How Does a Facility Report Batteries for Tier II?
7
U.S. Environmental Protection Agency. Chemicals in Facility Pipelines and the EPCRA Transportation Exemption
8
Environmental Protection Agency. Chapter 2 – EPCRA Section 302: Emergency Planning Notification
9
U.S. Environmental Protection Agency. Emergency Planning
10
U.S. Environmental Protection Agency. EPCRA Emergency Release Notifications
11
eCFR. 40 CFR Part 370 – Hazardous Chemical Reporting: Community Right-to-Know
12
eCFR. 40 CFR Part 19 – Adjustment of Civil Monetary Penalties for Inflation
13
Office of the Law Revision Counsel. 42 U.S.C. 11045 – Enforcement