Arizona is updating its hazardous-waste rules. Here is what to watch.

The short version

ADEQ has opened a rulemaking docket to update 18 A.A.C. Chapter 8, Article 2, Arizona's hazardous-waste rules. The docket covers R18-8-260 through R18-8-273 and has three main parts:

Arizona's current incorporation by reference generally stops at July 1, 2020. In an authorized state such as Arizona, a later federal rule does not necessarily become part of the state-administered program immediately. The result depends on whether the rule was issued under the Hazardous and Solid Waste Amendments, whether it is more or less stringent, and whether state adoption is required or optional. This rulemaking would update Arizona's rules and begin closing that gap.

Docket source: Notice of Rulemaking Docket Opening, File No. R26-45, 32 A.A.R. 842 (April 10, 2026).

Timeline and why the next few weeks matter

ADEQ has not yet published a Notice of Proposed Rulemaking or opened the formal public-comment period. The docket notice says the comment period and agency timetable will be announced with the proposed rule.

The September meeting is therefore an early opportunity to raise implementation concerns before proposed language is publicly filed. Under Arizona's rulemaking procedure, the docket generally terminates if a proposed rule is not filed within one year after publication, making April 10, 2027 the outside date for filing under this docket unless another provision applies.

The seven federal rules and who should care

You probably do not need to study all seven. Start with the operational descriptions below.

Most generators can skip these

Read these if the description fits

Technical corrections

Two additional rules correct provisions in the Generator Improvements Rule, Pharmaceuticals Rule, and Definition of Solid Waste Rule, all of which Arizona has already adopted. EPA describes the corrections as fixing typographical errors, incorrect citations, and language that was unintentionally ambiguous across roughly 50 sections. EPA also classifies the corrections as neither more nor less stringent than current requirements.

Most are not new compliance obligations, but a few can affect how an existing procedure is carried out. For example, the episodic-generation correction expressly requires a very small quantity generator shipping episodic-event waste to follow the small quantity generator recordkeeping provisions in 40 CFR 262.44, including manifest records and exception reporting. Other corrections touch labeling, hazardous waste pharmaceuticals, large quantity generator accumulation-unit closure, and contingency-planning references for certain hazardous secondary material recycling provisions.

If you built a procedure around specific language in one of these rules, it is worth confirming that a correction did not touch the provision you relied on.

88 FR 54086 and 89 FR 99727

The fee change and the unanswered question

This is the part of the rulemaking with the greatest potential financial impact, yet ADEQ's public explanation leaves an important question unanswered.

ADEQ describes the change as replacing the national Consumer Price Index for All Urban Consumers with the October Phoenix-Mesa-Scottsdale index because a regional index better reflects inflation in Arizona. The Phoenix index covers Maricopa and Pinal Counties, not the state as a whole. Changing the index is also only part of the story.

The current hazardous-waste rule uses the national index, compares December to December, and builds each adjustment on the prior year's fee. It does not limit how much a fee can increase in one year. The maximum dollar amounts in the rule cap total site fees, not annual inflation adjustments.

For comparison, ADEQ's newer solid-waste fee rules combine the October Phoenix index and fixed-base calculation with a four-percent annual cap.

ADEQ may intend to use that same cap here. That is an inference from its parallel solid-waste provisions, not a feature ADEQ has announced for this rulemaking. The hazardous-waste rule is not final, and neither the docket notice nor the FAQ says whether the cap will be included.

What the recent numbers show

The annual adjustments under the current method were approximately 3.34 percent, 2.90 percent, and 2.68 percent for 2024 through 2026. These percentages were derived from ADEQ's published fee schedule, not published separately by ADEQ, and they reproduce the posted rates across all fee categories.

*The 2026 Phoenix figure assumes that the missing October 2025 index results in no adjustment, which is the plausible default unless the rule provides a fallback.

For a large quantity generator shipping 900 tons per year and remaining below the per-site maximum, that is approximately $85,500 under the current fee and $81,900 under the Phoenix method, a difference of about four percent.

If ADEQ carries the four-percent cap across and addresses the missing-data problem, the change appears favorable and worth supporting. If ADEQ adopts the regional index without the cap, generators receive metro-level volatility with no ceiling.

The ignitability clarification

The revised federal text at 40 CFR 261.21(a)(1) excludes a liquid from that paragraph's flash-point criterion when it is a solution containing less than 24 percent alcohol by volume and at least 50 percent water by weight.

“Other than a solution containing less than 24 percent alcohol by volume and at least 50 percent water by weight”

The prior text used “aqueous solution” without defining aqueous in the regulation. EPA had long interpreted the term through guidance as requiring at least 50 percent water by weight. The 2020 rule placed that interpretation directly into the regulatory text.

This is a clarification, not a new threshold

EPA classified this part of the rule as less stringent, making state adoption optional. If Arizona adopts it, a generator can support the water component of the exclusion directly from the regulatory text instead of relying primarily on EPA guidance.

The method update expands laboratory options

Methods 1010B and 1020C recognize additional ASTM standards and allow non-mercury temperature-measurement devices. The rule does not require a generator to use every listed method, nor does it automatically invalidate a suitable mercury-based method. The selected method should fit the waste, and the waste-determination file should identify the method or document the process knowledge used.

What to do before September 3