What goes wrong

Diluted to get under the number

Updated October 2026

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How it happens The clause, again It is not a technicality And it happens by accident more than by design Which also preserves the silver Sewer discharge is a separate permission So the honest arrangement Separation costs one container and a marker References

The most natural idea in the category, and the rule names it.

How it happens

Spent fixer goes into a carboy that already holds wash water, or into the sink with the taps running, and the reasoning is that the concentration is now low. The determination was due before that happened.

The clause, again

The determination must be made at the point of waste generation, before any dilution, mixing, or other alteration of the waste occurs. Dilution and mixing are both named.

It is not a technicality

The silver has not gone anywhere. Diluting changes the concentration in the container and not the mass of silver heading for the sewer or the ground, which is what the rule is actually about.

And it happens by accident more than by design

One carboy under the bench for everything is a tidy arrangement and it mixes the streams. Keeping the fixer separate takes a second container and a label, and that is the whole intervention.

Which also preserves the silver

A recovery service wants spent fixer unmixed, because that is where the recoverable silver is. Mixing it with wash water destroys the commercial value as well as the determination.

Sewer discharge is a separate permission

Many municipalities regulate silver to the sewer under their own pretreatment rules, with their own limits, independent of RCRA. Being right federally does not mean a drain is an option.

So the honest arrangement

Spent fixer into its own labeled container at the point of generation, held for a recovery service or a hazardous waste contractor, with the determination written down. Everything else follows from that.

Separation costs one container and a marker

Which is the whole intervention. A second labeled carboy at the tray preserves the determination, preserves the recoverable silver and prevents the failure, and it is the cheapest line in this property.

References

40 CFR 262.11, Hazardous waste determination and recordkeeping. The determination must be made at the point of waste generation, before any dilution, mixing or other alteration occurs, and again if the properties change; and it may be made using knowledge of the waste including its origin, composition, the process producing it and the feedstock. law.cornell.edu

40 CFR 261.24, the Toxicity characteristic. A solid waste exhibits it where the Toxicity Characteristic Leaching Procedure extract contains a Table 1 contaminant at or above the listed level, and where the waste contains less than 0.5 percent filterable solids the waste itself is considered to be the extract. Table 1 lists D011 Silver at 5.0 mg/L. law.cornell.edu

Written from federal regulation and from measured catalog data, not from a darkroom. Hazardous waste regulation is federal with authorized state programs on top, and many states and municipalities regulate silver discharge to sewer separately. The determination for a specific waste is the generator’s to make.