StacksVerified U.S. regulatory reference

40 CFR §421.256

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Except as provided in 40 CFR 403.7, any new source subject to this subpart which introduces pollutants into a publicly owned treatment works must comply with 40 CFR part 403 and achieve the following pretreatment standards for new sources. The mass of wastewater pollutants in primary precious metals and mercury process wastewater introduced into a POTW shall not exceed the following values:
  1. (a)Smelter wet air pollution control.
  2. (b)Silver chloride reduction spent solution.
  3. (c)Electrolytic cells wet air pollution control.
  4. (d)Electrolyte preparation wet air pollution control.
  5. (e)Calciner wet air pollution control.
  6. (f)Calcine quench water.
  7. (g)Calciner stack gas contact cooling water.
  8. (h)Condenser blowdown.
  9. (i)Mercury cleaning bath water.