Read 40 CFR part 430 at the scope it actually has

Which subcategory governs is a determination

40 CFR 430.00 applies to any pulp, paper or paperboard mill that discharges or may discharge process wastewater pollutants to waters of the United States, or that introduces or may introduce them into a publicly owned treatment works. It then divides that universe into twelve subcategories, A through L, keyed to the pulping route and to the product: Dissolving Kraft; Bleached Papergrade Kraft and Soda; Unbleached Kraft; Dissolving Sulfite; Papergrade Sulfite; Semi-Chemical; Mechanical Pulp; Non-Wood Chemical Pulp; Secondary Fiber Deink; Secondary Fiber Non-Deink; Fine and Lightweight Papers from Purchased Pulp; and Tissue, Filter, Non-Woven, and Paperboard from Purchased Pulp.

The subcategories are not interchangeable and they are not uniformly complete—subpart H reserves its new-source performance standards and both pretreatment standards, while subparts B and E carry an entire additional apparatus the others do not. Which one governs a given mill is a written determination somebody owns, and the limitations that follow are expressed as mass per unit of production. Subpart B’s best-practicable-technology limits for a bleached kraft mill producing market pulp, for example, are 15.45 kg of BOD₅ per 1,000 kg of product as a maximum for any one day and 8.05 as a 30-day average, with TSS at 30.4 and 16.4 on the same basis and pH held within 5.0 to 9.0 at all times. Those are limits on a mill’s output, not on anything in a drum.

What the category regulates

EPA’s summary page records the history in one paragraph: initial guidelines for the category in 1974 and 1977, amendments in 1982 and 1986, and a major 1998 amendment covering toxic pollutants—the “Cluster Rule,” which promulgated air standards for the industry under the Clean Air Act at the same time. The page was last updated March 24, 2026.

It also lists the regulated pollutants by class, and the shape of that list is the useful part. Conventional: biochemical oxygen demand, suspended solids, and pH. Priority: 2,4,6-trichlorophenol, 2,3,7,8-TCDD, pentachlorophenol and zinc. Nonconventional: adsorbable organic halides, chemical oxygen demand, chloroform, trichlorosyringol, and a series of trichloro- and tetrachloro- catechols, guaiacols and phenols. Almost every entry after the first three is a chlorinated organic. That is the category’s centre of gravity, and it is the reason the regulation cares so much about exactly where and with what a fiber line is bleached.

The bleach plant has a boundary written in the rule

40 CFR 430.01(c) defines the bleach plant as all process equipment used for bleaching “beginning with the first application of bleaching agents (e.g., chlorine, chlorine dioxide, ozone, sodium or calcium hypochlorite, or peroxide), each subsequent extraction stage, and each subsequent stage where bleaching agents are applied to the pulp,” and it excludes oxygen delignification carried out before bleaching agents are applied. 430.01(f) then defines elemental chlorine-free as any process bleaching “in the absence of elemental chlorine and hypochlorite that uses exclusively chlorine dioxide as the only chlorine-containing bleaching agent.” Hypochlorite is named on both sides of that line, in the list of bleaching agents and in the exclusion.

The regulation also anticipates a mill changing its bleaching chemistry. 430.01(j)(2) lists changes that do not by themselves make an existing mill a new source, and paragraph (iv) reads: “Bleach plant modifications including changes in methods or amounts of chemical applications, new chemical applications, installation of new bleaching towers to facilitate replacement of sodium or calcium hypochlorite, and installation of new pulp washing systems.” What follows from a change is monitoring, not permission. 430.02(a) sets minimum frequencies for subpart B and E discharges keyed to the bleaching route: for a fiber line that is not exclusively totally chlorine-free, AOX daily, chloroform weekly, and the chlorinated phenolics monthly. For a line that is, the same table specifies no monitoring frequency for AOX and records that the regulation specifies no limit for the individual chlorinated phenolics—those lines are instead given their own AOX limitation of less than the minimum level at § 430.24(a)(2). Which route a line uses is disclosed by the discharger in its permit application under 40 CFR 122.21(g)(3) and certified under 40 CFR 122.22. None of this is something a chemical supplier can determine, and nothing in this library states that any product is suitable, approved or recommended for a bleaching stage, nor supplies an application rate.

The rule names an internal owner

40 CFR 430.03 requires best management practices for spent pulping liquor, soap and turpentine at direct and indirect discharging mills with pulp production in subparts B and E. Its primary objective is to prevent leaks and spills; its secondary objective is to contain, collect and recover them at the immediate process area. The obligations are concrete: return spilled or diverted material to the process to the maximum extent practicable, run a programme to identify and repair leaking equipment with regular visual inspections and a means of tracking repairs over time, and operate the continuous automatic monitoring the mill determines is necessary—high-level alarms on storage tanks, conductivity or pH monitors in process areas and sewers.

Two definitions in that section are worth a purchasing team’s attention. An action level is “a daily pollutant loading that when exceeded triggers investigative or corrective action,” and mills set it themselves by statistical analysis of six months of their own daily measurements—the rule offers the 75th and 90th percentiles of running seven-day averages as an example, not a requirement. And the BMP plan is reviewed by a “senior technical manager,” defined as the chief engineer, the manager of pulping and chemical recovery operations, or another responsible person designated by the mill manager who has knowledge of and responsibility for those operations. The regulation names an internal owner because there is no external one. A purchase record should name the same person.

What this brief did not read

The analytical apparatus behind the category is partly in the regulation and partly outside it. Methods 1650 for AOX and 1653 for the chlorinated phenolics are printed in Appendix A to part 430, and 40 CFR 430.01(i) fixes their minimum levels—20 µg/L for AOX, 2.5 or 5.0 µg/L for the individual phenolics, and 10 pg/L for 2,3,7,8-TCDD by Method 1613. Part 136 governs approved test procedures for the analysis of pollutants more generally. All of these were promulgated for discharge reporting. An approved discharge method is not an acceptance test for a delivered drum, and a minimum level is not a purity limit.

TAPPI standards and ASTM test methods are the documents a mill specification is most likely to invoke for the material itself, and both are sold by their publishers. Neither was readable while this brief was written, so neither is paraphrased here and no limit is reproduced from either. Where a specification cites one, obtain the edition invoked and cite the clauses by number. This brief performed no original testing, evaluates no study, and makes no waste, permit or exposure determination—those belong to the mill, its environmental professional and its permitting authority. Independent specialist review of this collection is pending.

• Which subpart of 40 CFR part 430 governs this mill, and who made and recorded that determination?
• Is the fiber line certified as non-TCF, ECF or TCF, and what monitoring frequency follows from that certification?
• Does the material enter inside or outside the bleach plant boundary as § 430.01(c) draws it?
• Who is the senior technical manager for the BMP plan, and who is the named permit holder reporting against the limits?

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

Revision record

1.0 · September 12, 2026 — Source-based editorial edition. No original testing or product qualification is claimed.

For pulp, paper and paperboard mills and their purchasing teams specifying bulk caustic, bleaching chemistry, coagulants and reducing agents. This collection does not select a bleaching sequence, set a dose or an application rate, design a stock or water circuit, or make a discharge, permit or waste determination.