Class I Injection Wells: Permit Rules, State Agency Splits, and the Arbuckle Pressure Problem
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Class I Injection Wells: Permit Rules, State Agency Splits, and the Arbuckle Pressure Problem

Class I injection well permitting, state by state: a different agency in Kansas, Oklahoma, Texas and Nebraska, EPA direct in Colorado, and banned in Missouri.

by iSi Environmental

If your plant is in Kansas and you are pricing a deep disposal well for process wastewater, the regulator has already told you something worth hearing. The Kansas Department of Health and Environment reports on its Underground Injection Control page that while Class I injection volumes have held steady, formation pressure has increased and fluid levels have risen noticeably in some Class I wells. As fluid levels climb toward the surface, KDHE says, a well can lose its ability to operate. The agency now requires a Waste Minimization Plan as a permit condition.

Nobody can tell you which agency you are applying to until they know your state and your waste. In Kansas, Oklahoma and Texas, industrial deep disposal and oil-and-gas disposal sit with different agencies. In Colorado there is no state agency. In Missouri the well is illegal. Below are the federal Class I underground injection control permit requirements, then the agency answer for each state iSi serves.

What exactly makes a well a Class I injection well?

Under 40 CFR 144.6(a), a Class I well injects hazardous waste, other industrial or municipal wastewater, or radioactive waste beneath the lowermost formation containing an underground source of drinking water within one-quarter mile of the well bore. The defining test is depth relative to drinking water. Waste type alone does not settle it. 40 CFR 146.5(a) carries the identical classification.

These are the deepest disposal wells in the federal program, with typical injection zones from 1,700 feet to more than 10,000 feet. KDHE puts it plainly: Class I is for wastewater that cannot feasibly be treated, stored or disposed of another way.

How is a Class I hazardous well different from a Class I non-hazardous well?

40 CFR 146.61(a) says Subpart G applies instead of Subpart B for hazardous wells. The practical deltas: a fixed 2-mile Area of Review against a quarter-mile-minimum option, annual pressure testing plus an annual radioactive tracer survey against one mechanical integrity test every five years, mandatory tubing and packer, post-closure care, a perpetual deed notation, and a Part 148 no-migration petition.

Subpart G also brings casing cemented to surface at a minimum of 120 percent of calculated annular volume (146.65(c)) and financial responsibility for plugging and post-closure under Part 144 Subpart F and 146.73. Non-hazardous wells run under the lighter Part 146 Subpart B. Which subpart you land in gets decided by the analytical lab.

How long is a Class I UIC permit good for?

40 CFR 144.36(a) sets a fixed term not to exceed 10 years for Class I and Class V permits. The mandatory five-year permit review in that same subsection applies only to Class II, III and VI wells, a distinction routinely misreported. Oklahoma DEQ confirms the 10-year term and allows operation under an expired permit if renewal is filed before expiration.

If guidance tells you a Class I permit reopens every five years, check the citation. That clock belongs to other well classes.

How big is the Area of Review I have to study?

For a Class I hazardous well, 40 CFR 146.63 fixes the Area of Review at a 2-mile radius around the well bore, with the Director able to enlarge it based on the cone of influence. Elsewhere, 40 CFR 146.6 permits either a modeled zone of endangering influence or a fixed radius of not less than one-quarter mile.

The 2-mile figure has no discretion downward and drives application cost more than any other number. Inside it you owe a tabulation of every well penetrating the injection or confining zone plus plugging records for each (146.64). Anything improperly plugged goes into a corrective action plan that becomes a permit condition, capped at 2 years for existing wells and finished before first injection for new ones.

How often must I run a mechanical integrity test?

Class I hazardous wells under 40 CFR 146.68(d) need an annual pressure test of long-string casing, injection tube and annular seal, plus workovers; an annual radioactive tracer survey of bottom-hole cement; and a temperature or noise log at least once every five years. Class I non-hazardous wells demonstrate mechanical integrity at least once every five years, 40 CFR 146.13(b)(3).

Under 146.67(h), a loss of mechanical integrity means immediate shut-in and notice to the Director within 24 hours.

What does the no-migration petition actually have to prove?

40 CFR 148.20(a)(1)(i) requires a showing, to a reasonable degree of certainty, that injected fluids will not migrate vertically out of the injection zone or laterally to an underground source of drinking water within 10,000 years, or alternatively that the fluid ceases to be hazardous before it gets there. Mechanical integrity tests must be under one year old at submission.

The petition applies whenever RCRA-restricted waste goes down the well, and it carries an Area of Review meeting 146.63, well condition data per 146.64, the certification at 148.22(a)(4), and sensitivity analysis. The Director re-examines it at every reissuance.

Is there any federal exemption from the Class I permit requirement?

Very little. 40 CFR 144.31(a) prohibits all injection activity, including well construction, until a permit is issued, unless authorized by rule under Subpart C, which does not reach new Class I disposal. 40 CFR 148.1(d) adds one narrow carve-out: characteristic-only hazardous wastes are not Part 148 prohibited if they no longer exhibit a prohibited characteristic at the point of injection.

Sequence construction against 144.31(a). Drilling ahead of the permit is itself the violation.

How long is the public comment period on a draft Class I permit?

40 CFR 124.10(b)(1) requires at least 30 days for public comment on a draft UIC permit, and at least 30 days’ notice before any hearing. 40 CFR 124.10(c)(1)(vii) adds a Class-I-specific requirement: notice must be mailed to state and local oil and gas regulatory agencies and to state mineral exploration and recovery agencies.

Up front, 40 CFR 124.3(c) sets a completeness review target of 30 days for a new injection well and 60 days for an existing one. No agency publishes a median for total Class I issuance time, so treat a quoted schedule as an opinion.

Six states, six answers on who holds your permit

Every state below holds Section 1422 primacy for Class I except Colorado. Two rows correct the CFR.

StateClass I agencyRule citationNotes
KansasKDHE, Bureau of Water, Geology SectionK.A.R. 28-46-1 through 28-46-42; K.S.A. 65-161, 65-164 to 65-166a, 65-171dSection 1422 primacy, 48 FR 54350. Class II is the Kansas Corporation Commission. FY24: 7 hazardous, 61 other. Nearly all inject into the Arbuckle.
OklahomaOklahoma DEQ, Land Protection DivisionOAC 252:652; fees at 27A O.S. 2-7-119 to 2-7-122 and OAC 252:205 Subch. 21Section 1422 primacy, 47 FR 27273. CFR text is stale: 40 CFR 147.1850 still names the “Oklahoma State Department of Health.” DEQ is the live agency. Class II is the Oklahoma Corporation Commission. DEQ reports five Class I non-hazardous wells; EPA FY24 shows 7.
MissouriNone. Class I wells are banned.10 CSR 20-6 series; Chapter 259 RSMo for Class IIMoDNR fact sheet PUB2883 states Class I injection wells are banned, as are Class IV. EPA FY24: 0 Class I wells. Class V is permitted; Class III is regulated but none issued.
NebraskaNebraska Department of Water, Energy and Environment (DWEE), formerly styled NDEETitle 122, Rules and Regulations for Underground Injection and Mineral Production WellsSection 1422 primacy. Class II is the Nebraska Oil and Gas Conservation Commission. DWEE says four Class I wells operate; a July 2024 release said five permitted; EPA FY24 shows 11.
TexasTCEQ, Radioactive Materials Division, UIC Permits30 TAC Chapter 331; Texas Water Code Chapter 27Section 1422 primacy since 1982. Class II and Class III brine mining sit with the Railroad Commission, which also took Class VI effective 2025-12-15. FY24: 73 hazardous, 86 other.
ColoradoEPA Region 8, direct implementation. No state Class I program.40 CFR Parts 124, 144, 146 and 148 apply directly; state additions at 40 CFR 147.302 to 147.30540 CFR 147.301(a) puts Class I, III, IV and V on all Colorado lands with EPA. Class II is the Colorado Energy and Carbon Management Commission. FY24: 13 wells, none hazardous.

Across the footprint: Texas 159 Class I wells, Kansas 68, Colorado 13, Nebraska 11, Oklahoma 7, Missouri zero.

Who regulates Class I injection wells in Kansas?

The Kansas Department of Health and Environment, Bureau of Water, Geology Section. 40 CFR 147.850 grants KDHE Safe Drinking Water Act Section 1422 primacy for Class I, III, IV and V wells effective 1983-12-02 (48 FR 54350), under K.A.R. 28-46-1 through 28-46-42. The Kansas Corporation Commission handles Class II only, under Section 1425 primacy.

Kansas holds the third-largest Class I inventory in the country, and the application package starts at KDHE’s Class I forms page.

Can I put a Class I disposal well in Missouri?

No. The Missouri DNR fact sheet PUB2883 states that Class I injection wells are banned in Missouri. EPA’s FY 2024 State UIC Inventory records zero Class I hazardous and zero Class I other wells in the state. The Water Protection Program permits Class V UIC wells (Class III is regulated but no permits have been issued); Class II sits with the Missouri Geological Survey under Chapter 259, RSMo.

At a Missouri plant the conversation moves to treatment or off-site management.

Does Texas TCEQ or the Railroad Commission handle my industrial disposal well?

TCEQ. Under 40 CFR 147.2200, Texas holds Section 1422 primacy for Class I, III, IV and V wells through TCEQ, effective 1982-02-07 with a 2004 revision. The Railroad Commission holds Section 1425 Class II primacy and, since 2025-12-15, Section 1422 Class VI primacy. TCEQ notes the Railroad Commission reviews and comments on Class I applications.

Comment rights do not make the Railroad Commission your permitting agency. TCEQ issues the permit.

What does a Class I permit cost in Oklahoma?

Oklahoma DEQ’s fee schedule (27A O.S. 2-7-119 to 2-7-122; OAC 252:205 Subchapter 21; OAC 252:652-1-6) sets a hazardous-waste injection well permit application at the $3,000 base fee plus $15,000, and a non-hazardous injection well at a $2,000 application fee with a $500 renewal. Annual injection fees run $0.03 per gallon hazardous and $0.0002 per gallon non-hazardous, capped at $50,000.

Oklahoma is the one state in the footprint that publishes a clean, verifiable Class I fee schedule. The $18,000 hazardous application against the $2,000 non-hazardous application is the sharpest dollar illustration of what waste characterization buys you. No Kansas or Texas fee appears here; neither could be verified against a primary source.

How much can EPA fine me for a UIC violation?

Per 40 CFR 19.4 Table 1, for violations after 2015-11-02 assessed on or after 2025-01-08: judicial civil penalties up to $71,545 per day under 42 USC 300h-2(b)(1), and administrative penalties for Class I wells up to $28,619 per day capped at $357,729 under 300h-2(c)(1). Willful violations carry up to three years’ imprisonment under 300h-2(b)(2).

The enforcement record is more instructive than the ceilings, and none of it involves contaminated aquifers. In consent agreements dated 2025-04-07, EPA penalized McKittrick Limited $19,363 and Live Oak Limited $19,364 on the same theory: failure to timely establish and report a historic cyclic range of annular pressures during normal operating conditions, in violation of 40 CFR 144.51(a). EPA’s Imperial Irrigation District settlement, announced 2023-04-11, covered two Class I non-hazardous wells and three permit-condition failures found in a virtual inspection: failure to maintain required pressure, failure to report pressure drops, and no continuous monitoring data. Penalty $67,110.

The continuous-recording duties at 146.67(f) and the quarterly reporting duties at 146.69 are where operators get caught, and both are administrative work a plant can staff correctly.

One caveat. The most recent Part 19 inflation adjustment is 90 FR 1375, published 2025-01-08, and no later adjustment appears as of the 2026-08-27 eCFR issue date. These are the operative amounts for penalties assessed on or after 2025-01-08, and a catch-up rule could raise them.

Four things the market gets wrong about Class I disposal

Oklahoma did not restrict Class I disposal because of earthquakes. The state’s seismicity response sits with the Oklahoma Corporation Commission, whose Induced Seismicity and UIC Departments describe their mission as mitigating induced seismicity risk related to oil and gas activity. OCC’s jurisdiction is Class II saltwater disposal. DEQ holds Class I and keeps issuing 10-year permits. Anyone saying Oklahoma clamped down on industrial deep disposal over seismicity has conflated two agencies and two well classes.

The seismicity issue does reach Class I in Kansas, through pressure. KDHE’s UIC page states that Kansas earthquake activity has correlated with Arbuckle injection volumes, that Kansas Geological Survey research indicates earthquakes and injection volumes are connected, and that re-examined Class I data shows steady injection volumes alongside rising formation pressure and noticeable fluid level rise in some wells. The volume a Kansas generator can plan on 15 years out is now an engineering question the permit asks you to answer.

Class I is not shrinking. EPA’s March 2001 study, EPA 816-R-01-007, counted 473 Class I wells on 1999 data. The FY 2024 State UIC Inventory counts 930: 132 hazardous, 798 other. The honest caveat is that the FY 2024 file counts Proposed, Under Construction, Active and Temporarily Abandoned wells while EPA’s narrative page cites roughly 800 operational wells, so the comparison overstates growth. The population is still not contracting, and no primary-source data showing treatment displacing Class I disposal was located.

The permit-backlog story is real for carbon storage and unproven for Class I. EPA OIG Report 25-E-0045, issued 2025-07-28, found EPA is not on track to issue final Class VI permits within its 24-month goal. Of 36 applications with 2024 decision dates, 24 were expected to land late, averaging 212 days over. Of 138 applications under review in May 2024, 40 percent of completeness determinations exceeded the 30 days at 124.3(c). Regions 5, 6 and 9 told OIG they lacked the capacity to meet the goal, and Region 6 covers Texas and Oklahoma. The limit worth stating plainly: OIG examined Class VI, not Class I. Treat it as forward-looking risk, not a measured slowdown.

There has also been no substantive federal Class I rulemaking in 2025 or 2026. The movement is all at the state layer.

Where to start if you are evaluating deep-well disposal

Confirm the class and the agency first, because a Class I application sent to a Class II regulator costs months. Characterize the waste next, since hazardous against non-hazardous decides the Area of Review, the mechanical integrity schedule, post-closure care and whether you owe a Part 148 petition. If you already run a Class I well, pull your last four quarterly reports and your annulus pressure records against 146.67 and 146.69 and see whether they would survive the inspection that produced the cases above, ideally inside an environmental compliance audit.

That sequence is where iSi works. We handle the waste characterization that decides which subpart your well falls under, we build the permit application package for the agency that actually holds your class, and we run the compliance monitoring and recordkeeping the quarterly reporting and mechanical integrity schedules demand. We Plug In alongside the environmental staff you already have rather than replacing them, and You Level Up on a program most plant teams build once in a career. If deep-well disposal is on your capital plan, settle the characterization and the agency question before the application gets drafted.

Sources

Federal regulations (eCFR), verified 2026-08-31

Statute

Federal Register

U.S. EPA

State agencies

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