REM Practice Questions (2026) — Free Sample Questions with Answers

Answer: C

The group may still sue, because its notice was timely and proper: Proper notice is necessary but not sufficient; diligent government prosecution in court bars the suit.

The group's suit must be merged into a state administrative order: The bar here comes from a court action, and the statute gives no merger into an administrative order.

The group may not sue but may intervene in the court action as of right: Correct. CWA §505(b)(1)(B) bars a citizen suit when EPA or the state has commenced and is diligently prosecuting a civil or criminal action in court for the same violations, but any citizen may intervene in that action as a matter of right.

The group may sue only for civil penalties the state did not seek: There is no carve-out for penalties not sought; the citizen suit is barred while the government diligently prosecutes.

Citizen suits supplement, not replace, government enforcement: diligent prosecution in court bars them, but citizens may intervene.

Answer: B

It is covered as a Program 1 process, because propane is flammable: Program level is not assigned here because the fuel exclusion removes the propane from the rule.

It is not covered, because flammables used as fuel are excluded: Correct. CAA §112(r)(4)(B), added by the 1999 Chemical Safety Information, Site Security and Fuels Regulatory Relief Act, and 40 CFR 68.126 exclude a listed flammable substance used as a fuel, or held for sale as a fuel at a retail facility, from the RMP rule even above the threshold quantity. In its March 13, 2000 rule (65 FR 13243), EPA interprets the fuel-use exclusion as available to any facility that uses the flammable as fuel, not only retail facilities, so propane burned in the plant's own ovens is excluded. The General Duty Clause of §112(r)(1) still applies.

It is covered as a Program 3 process, because the quantity exceeds 10,000 lb: Exceeding the threshold quantity does not matter when the substance is used as a fuel and is excluded.

It is not covered, because propane is regulated only under OSHA PSM: Propane is a listed RMP flammable; it is excluded here because of its fuel use, not because OSHA regulates it.

Under 40 CFR 68.126, as EPA interprets it (65 FR 13243), a listed flammable used as fuel at any facility is excluded from RMP; only fuel held for sale at a non-retail facility stays covered, and the General Duty Clause still applies.

Answer: C

1. 1. PSD major-source threshold for an unlisted category: 250 tpy. 180 tpy < 250 tpy, so PSD is not triggered.
2. 2. Title V major-source threshold: 100 tpy of any regulated air pollutant. 180 tpy ≥ 100 tpy, so Title V applies.
3. 3. HAPs are each under 10 tpy, so the source is not a HAP major source, but it is already a Title V major source because of VOC.

Both PSD preconstruction review and a Title V operating permit: PSD review is not triggered: for an unlisted source category the PSD major-source threshold is 250 tpy, and 180 tpy is below it.

PSD preconstruction review only: PSD does not apply at 180 tpy for an unlisted category, while Title V does apply at 100 tpy.

A Title V operating permit only: Correct. Under 40 CFR 52.21(b)(1) a source outside the 28 listed categories is a PSD major source only at 250 tpy, so 180 tpy VOC does not trigger PSD. Title V (CAA §501(2), 40 CFR 70.2) defines a major source as 100 tpy of any air pollutant, so the plant needs a Title V operating permit (state minor NSR may still apply).

Neither program, because the area is in attainment: Attainment status matters for choosing PSD over nonattainment NSR, but Title V applies to major sources wherever they are located.

PSD: 100 tpy for the 28 listed categories, 250 tpy for all others. Title V: 100 tpy of any air pollutant (lower in some nonattainment areas), 10/25 tpy HAP.

Answer: A

1. 1. Buried capacity: 2 × 22,000 = 44,000 gal, but both USTs are subject to all 40 CFR 280 technical requirements, so they are excluded; counted buried capacity = 0 gal.
2. 2. Aboveground containers ≥ 55 gal: used oil tank 1,000 gal + drums 4 × 55 = 220 gal, for 1,220 gal.
3. 3. Pails (30 × 5 = 150 gal) are under 55 gal each and are not counted.
4. 4. 1,220 gal does not exceed 1,320 gal and 0 does not exceed 42,000 gal, so the facility is not subject to SPCC.

No; only 1,220 gal of aboveground capacity counts: Correct. Completely buried tanks subject to all technical requirements of 40 CFR 280 are excluded from the buried-capacity count, and containers under 55 gal are not counted (40 CFR 112.1(d)(2)). The counted aboveground capacity is 1,000 + 220 = 1,220 gal, which does not exceed 1,320 gal, so the rule does not apply.

Yes; aboveground capacity of 1,370 gal exceeds 1,320 gal: This total wrongly counts the 5-gal pails; only containers of 55 gal or more are counted.

Yes; buried capacity of 44,000 gal exceeds 42,000 gal: The buried USTs are fully subject to 40 CFR 280, so they are excluded from the 42,000-gal buried-capacity count.

Yes; total oil storage of 45,370 gal exceeds both thresholds: The aboveground and buried thresholds are applied separately, and this total includes excluded tanks and containers.

For SPCC applicability, count aboveground containers of ≥ 55 gal against 1,320 gal and completely buried capacity against 42,000 gal, leaving out buried tanks fully regulated under 40 CFR 280.

Answer: C

1. 1. Process wastewater counted for the 25,000 gal/day test: 18,000 gal/day (noncontact cooling 9,000 and sanitary 4,000 are excluded).
2. 2. 18,000 < 25,000 gal/day, so the process-flow criterion is not met.
3. 3. 5% of POTW capacity: 0.05 × 2,000,000 = 100,000 gal/day; total flow 18,000 + 9,000 + 4,000 = 31,000 gal/day < 100,000.
4. 4. The plant is not categorical, so it is an SIU only if the control authority designates it.

It is a significant industrial user because its total flow exceeds 25,000 gal/day: The 25,000 gal/day criterion counts process wastewater only and excludes sanitary, noncontact cooling and boiler blowdown flows; 18,000 gal/day falls below it.

It is a significant industrial user because its flow exceeds 5% of the POTW's capacity: Five percent of 2,000,000 gal/day is 100,000 gal/day; even the 31,000 gal/day total is far below that.

It does not meet the flow criteria, but the control authority may still designate it: Correct. A non-categorical user is an SIU if it discharges an average of ≥ 25,000 gal/day of process wastewater, contributes ≥ 5% of the POTW's dry-weather hydraulic or organic capacity, or is designated by the control authority (40 CFR 403.3(v)(1)(ii)). Its 18,000 gal/day of process wastewater meets neither flow test, so only designation could make it an SIU.

It must obtain an NPDES permit because its flow exceeds 25,000 gal/day: An indirect discharger to a POTW is regulated through the pretreatment program, not an NPDES permit, whatever its flow.

The SIU flow test uses process wastewater only (≥ 25,000 gal/day) or ≥ 5% of POTW capacity; categorical users are always SIUs, and the control authority may designate others.

Answer: C

1. 1. Rank the results lowest to highest: 0.22, 0.35, 0.48, 0.61, 0.74, 0.90, 1.05, 1.22, 1.41, 1.88.
2. 2. Position of the 90th percentile: 10 samples × 0.9 = 9.
3. 3. The 9th value is 1.41 mg/L.
4. 4. 1.41 mg/L > 1.3 mg/L, so the copper action level is exceeded.

The 90th percentile is 0.886 mg/L, so there is no exceedance: 0.886 mg/L is the arithmetic mean of the samples; the rule uses the 90th percentile value, not the mean.

The 90th percentile is 1.22 mg/L, so there is no exceedance: 1.22 mg/L is the 8th-ranked value; with 10 samples the 90th percentile is the 9th value (10 × 0.9 = 9).

The 90th percentile is 1.41 mg/L, so the action level is exceeded: Correct. Ranked lowest to highest, the sample at position 10 × 0.9 = 9 is the 90th percentile under the Lead and Copper Rule's tap-sampling method (40 CFR 141 Subpart I). That value, 1.41 mg/L, exceeds the 1.3 mg/L copper action level. The exceedance is not an MCL violation, but it triggers treatment and other follow-up requirements.

The 90th percentile is 1.88 mg/L, so the action level is exceeded: 1.88 mg/L is the maximum (10th-ranked) result, not the 90th percentile; the conclusion is right but the value is wrong.

Rank lead or copper tap results lowest to highest, multiply the number of samples by 0.9, and compare the value at that position with the action level; an exceedance triggers follow-up requirements but is not itself a violation.

Answer: D

As applicable requirements, because the waste is hazardous: "Applicable" means the requirement legally covers the substance or action; the stem says it does not.

As to-be-considered guidance the remedy may disregard: TBCs are non-promulgated advisories; promulgated RCRA standards that are relevant and appropriate are binding ARARs.

As inapplicable, because CERCLA remedies are exempt from RCRA: §121(d) requires remedies to attain ARARs, including RCRA standards, unless a waiver applies.

As relevant and appropriate requirements the remedy must meet: Correct. A requirement that is not legally applicable but addresses problems sufficiently similar that its use is well suited to the site is "relevant and appropriate" (40 CFR 300.5). Under CERCLA §121(d), relevant and appropriate requirements must be met just as applicable ones are, unless waived.

ARARs include both legally applicable requirements and those relevant and appropriate to similar situations; both must be attained unless waived.

Answer: B

Innocent landowner: The innocent landowner defense requires that the buyer did not know and had no reason to know of the contamination; the Phase I told the developer.

Bona fide prospective purchaser: Correct. A BFPP may buy property knowing it is contaminated, provided all disposal occurred before acquisition, AAI was performed, and the buyer meets continuing obligations such as reasonable steps, cooperation and compliance with land-use restrictions (CERCLA §§101(40), 107(r)).

Contiguous property owner: That protection covers contamination migrating from a neighboring property, and it also requires no knowledge at purchase.

De micromis exemption: That exemption covers arrangers and transporters of very small amounts, not purchasers of contaminated land.

Knowing purchase of contaminated property is protected only through BFPP status, which requires AAI before acquisition and ongoing compliance with continuing obligations.

Answer: A

No NRC report, because it is a federally permitted release: Correct. CERCLA §101(10)(A) defines discharges in compliance with a CWA §402 (NPDES) permit as federally permitted releases, and §103(a) and 40 CFR 302.6(a) exclude federally permitted releases from NRC notification, even at or above the RQ.

An immediate NRC report, because the amount exceeds the RQ: Exceeding the RQ does not matter when the release is federally permitted; a discharge in compliance with the NPDES permit is excluded from §103.

An NRC report only if the discharge reaches the receiving water: An outfall discharge to surface water is a release into the environment, but the permit compliance makes it federally permitted and not reportable.

A written follow-up report to EPA within 30 days of the discharge: A written follow-up applies to continuous releases reported under 40 CFR 302.8, not to federally permitted releases.

Releases in compliance with a federal permit, such as an NPDES discharge within its limits, are federally permitted releases and need no CERCLA §103 report; an exceedance of the permit limit at or above the RQ is reportable.

Answer: C

1. 1. 2.1 mg/L < 5.0 mg/L, so the treated waste no longer exhibits the toxicity characteristic.
2. 2. LDR attached at generation (9.0 mg/L), so the 0.75 mg/L treatment standard still applies.
3. 3. 2.1 mg/L > 0.75 mg/L, so the waste is still prohibited from land disposal until it is treated further.

It may go to the landfill, because it is no longer a hazardous waste: Removing the characteristic is not enough; LDR attaches when the waste is generated and must still be met.

It may go to the landfill after a 90-day holding period: There is no holding period that substitutes for meeting the treatment standard.

It must be treated further to 0.75 mg/L before land disposal: Correct. LDR attaches when a characteristic waste is first generated, so a waste that has been decharacterized must still meet its treatment standard, including any underlying hazardous constituents, before land disposal (40 CFR 268.9(c)–(d)). At 2.1 mg/L, it exceeds 0.75 mg/L. Once it meets the standard, it may go to a Subtitle D landfill with a one-time notice and certification kept on file.

It must go to a hazardous waste landfill even after it meets 0.75 mg/L: A decharacterized waste that meets its LDR standard may go to a Subtitle D unit with a one-time notice and certification kept in the file.

Removing a characteristic does not end LDR: the waste must meet its treatment standard (and UHC standards) before land disposal.

Answer: B

1. 1. Exclude the used oil (900 kg, managed under part 279) and the universal waste lamps (40 kg), which 40 CFR 262.13(c) does not count.
2. 2. Non-acute hazardous waste counted: 70 kg + 45 kg = 115 kg.
3. 3. Acute hazardous waste: 0.4 kg, which is not more than 1 kg.
4. 4. 115 kg is above 100 kg and below 1,000 kg, so the plant is an SQG for March.

VSQG, because only the 70 kg of spent solvent counts: The paint sludge is also a hazardous waste and counts; 70 + 45 = 115 kg.

SQG, because 115 kg of non-acute hazardous waste counts: Correct. Under 40 CFR 262.13(c), used oil managed under part 279 and universal waste managed under part 273 are not counted. The counted non-acute waste is 70 + 45 = 115 kg, which is above 100 kg and below 1,000 kg, and the 0.4 kg of acute waste does not exceed 1 kg. The plant is an SQG for March (40 CFR 262.13(a)).

LQG, because the used oil and lamps raise the total above 1,000 kg: Used oil managed under part 279 and universal waste lamps are excluded from the count.

LQG, because any amount of acute hazardous waste triggers LQG status: LQG status for acute waste requires more than 1 kg in a month; 0.4 kg does not.

Count only the hazardous waste that 40 CFR 262.13(c) does not exempt, such as used oil under part 279 and universal waste, then compare the non-acute and acute totals with the category thresholds.

Answer: D

The former Appendix A table of hazardous substances: The rule replaces the Appendix A table to 49 CFR 172.101 with a cross-reference to 40 CFR 302.4, so the former table is no longer the list to use after December 2, 2026.

The marine pollutant list in the 172.101 appendix: The marine pollutant list (Appendix B) identifies marine pollutants, not CERCLA hazardous substances or RQs.

The EPCRA extremely hazardous substances list in 40 CFR 355: The EHS list sets EPCRA planning thresholds; it does not define DOT hazardous substances.

EPA's CERCLA hazardous substance list and RQs in 40 CFR 302.4: Correct. PHMSA's final rule (91 FR 49305, published August 4, 2026; effective December 2, 2026) revises Appendix A to 49 CFR 172.101 into a pointer to EPA's Table 302.4 in 40 CFR 302.4 and has the HMR definitions refer to that list for hazardous substances and their RQs. A material remains a DOT hazardous substance when one package holds at least its RQ.

From December 2, 2026, DOT hazardous substances and RQs are identified from EPA's list in 40 CFR 302.4; Appendix A to 49 CFR 172.101 only points to that list.

Answer: A

Applying it at a lower rate than the label specifies: Correct. FIFRA §2(ee)(1) states that applying a pesticide at a dosage, concentration or frequency less than the labeling specifies is not a use inconsistent with the labeling, unless the label prohibits it. Using it any other way the label does not allow is unlawful under §12(a)(2)(G).

Applying it at a higher rate to improve control: Exceeding the labeled rate is a use inconsistent with labeling and violates §12(a)(2)(G).

Applying it to a site that is not listed on the label: §2(ee) allows treating a pest not named on the label only at a labeled site; an unlisted site is a misuse.

Letting crews reenter treated areas before the restricted-entry interval ends: Ignoring label safety requirements such as restricted-entry intervals is a label violation.

The label is the law: deviations are allowed only as §2(ee) permits, such as a lower rate or frequency, or an unlisted pest at a labeled site, unless the label prohibits them.

Answer: C

OSHA PSM and RMP Program 1: Program 1 requires, among other things, that no public receptor be within the worst-case distance.

OSHA PSM and RMP Program 2: Program 2 is for processes not eligible for Program 1 and not subject to Program 3; PSM coverage moves this process to Program 3.

OSHA PSM and RMP Program 3: Correct. The process is above both thresholds. It is not eligible for Program 1 because a public receptor is within the worst-case distance, and a process subject to OSHA PSM that is not Program 1 eligible is in Program 3 (40 CFR 68.10).

OSHA PSM only, with no RMP coverage: PSM coverage does not exempt a process from the RMP rule; the two programs apply independently.

A process above the RMP threshold quantity that is not Program 1 eligible and is subject to OSHA PSM falls in RMP Program 3.

Answer: C

Source reduction, because less waste leaves the plant: Reducing the volume shipped is not source reduction when the waste is still generated in the same amount.

Recycling, because the water removed is reused: Nothing in the stem is reclaimed for reuse; dewatering for disposal is not recycling.

Treatment, because it changes the waste after it is generated: Correct. The Act excludes from source reduction any practice that alters the characteristics or volume of a hazardous substance through a step not integral to production (42 U.S.C. 13102(5)(B)). Dewatering sludge is end-of-pipe treatment.

Disposal, because the dewatered sludge is still landfilled: Disposal is the final step; the filter press itself is a treatment step before disposal.

If the same pollutant load is generated and only processed afterward, the project is treatment, not source reduction, even if shipped volume drops.

Answer: A

No, because discovery through legally required monitoring is not voluntary: Correct. One of the Audit Policy's nine conditions is voluntary discovery: the violation must not be found through monitoring, sampling or auditing required by statute, regulation, permit or order. CEMS data required by the Title V permit do not qualify.

Yes, a 100% gravity-based reduction, because it disclosed within 21 days: Prompt disclosure is only one condition; it cannot make up for discovery through required monitoring.

Yes, a 75% gravity-based reduction, because no audit was involved: The 75% reduction is for meeting every condition except systematic discovery; voluntary discovery is still required.

Yes, because it corrected the cause within 60 days: Timely correction is necessary but not sufficient.

Violations found by legally required monitoring or reporting are not eligible for Audit Policy credit.