Episodic generation of dangerous waste

The episodic generation rules allow small and medium quantity generators to maintain their current generator category, even when larger-than-normal waste amounts are generated from qualifying episodic events. Using this rule is optional.

To take advantage of this rule, you must notify Ecology's Hazardous Waste and Toxics Reduction Program (HWTR) program within specific timeframes based on the type of episodic event and fill out a Site ID form and an Episodic Addendum form.

If your unplanned event involves a spill of dangerous waste or hazardous substances, you must also report the spill. You must report any spill that poses a threat to human health or the environment, regardless of size.

NOTE: Unplanned events require immediate action.

Unplanned events: contact regional HWTR office within 72 hours. Submit forms within 30 days. Planned events: submit forms 30 days in advance

Notification deadlines and requirements for episodic events

What’s an episodic event?

Episodic event is an activity, either planned or unplanned, that:

  • Does not normally occur during generator operations.
  • Results in an increase of dangerous waste generated that exceeds the calendar month Quantity Exclusion Limits (QELs) for your generator category.

Planned vs. unplanned

  • Planned event is an episodic event you planned and prepared for, such as tank cleanouts, short-term projects, or removal of excess chemical inventory.
  • Unplanned event is an unexpected episodic event or one you did not plan for, such as a production process upset, product recall, accidental spill, or "act of nature," such as a tornado, hurricane, earthquake, flood, or wildfire.

You can manage waste from one planned or unplanned episodic event per calendar year under this rule provided you notify us correctly. Follow the instructions below.

How do I notify Ecology of an episodic event?

If you’d like to manage your dangerous waste under the episodic generation rules, you must:

  1. Get an EPA/State Identification Number (if you don’t already have one).
  2. Meet the notification deadlines for the type of episodic event.

Unplanned episodic event

Step 1

Notify the Hazardous Waste and Toxics Reduction Program in writing within 72 hours of your event.

Step 2

Submit the following forms by mail, postmarked within 30 days of your event: 

HWTR Annual Reporting Team
P.O. Box 47658
Olympia, WA 98504

Step 3

The HWTR Annual Reporting Team will email you to confirm all forms have been received and if there's anything further they need.

Planned episodic event

Step 1

Plan ahead:

  • We must receive your request (Step 2) at least 30 days before your planned event, but 60 days is recommended to ensure the entire review process can be completed in time.
  • If we receive your form less than 30 days before the proposed start date, we will change your start date to meet the minimum 30-calendar day requirement. We will inform you of the revised event start date.

Step 2

Submit the following forms by mail, postmarked at least 30 days before your event: 

HWTR Annual Reporting Team
P.O. Box 47658
Olympia, WA 98504

Step 3

Wait for confirmation that your forms have been received and accepted as complete.

  • We will contact you once your planned event paperwork has been accepted.
  • DO NOT proceed with a planned episodic event until you receive confirmation.

How should waste from an episodic event be handled?

On-site management requirements

Accumulate episodic waste in tanks and containers, which are:

  • In good condition.
  • Compatible with the dangerous waste.
  • Kept closed except when adding or removing waste.
  • Clearly marked or labeled.


Clearly label or mark your tanks and containers with the:

  • Words “Episodic Dangerous Waste” or “Episodic Hazardous Waste.”
  • Hazards associated with the waste (ignitable, corrosive, reactive, and/or toxic).
  • Episodic event start date.

Except for the start date, labels must be legible from 25 feet or the lettering size at least one-half inch in height. For containers one gallon (or four liters) and under, the label, marking, or lettering can be appropriate for the size of the container.

Read more about labeling requirements for dangerous waste.

Off-site disposal

Send episodic waste to a treatment, storage, and disposal facility within 60 calendar days from the start date of the event.

On-site treatment

Medium quantity generators may treat episodic waste within 60 calendar days from the start date of the event following treatment by generator guidance.

SQGs cannot treat episodic waste on site.

Frequently asked questions