Regulations last checked for updates: May 19, 2024

Title 40 - Protection of Environment last revised: May 16, 2024
All TitlesTitle 40Chapter IPart 421Subpart W - Subpart W—Primary Precious Metals and Mercury Subcategory
View all text of Subpart W [§ 421.250 - § 421.257]
§ 421.254 - Standards of performance for new sources.

Any new source subject to this subpart shall achieve the following new source performance standards:

(a) Smelter wet air pollution control.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/troy ounce of gold and silver smelted
Lead0.3640.169
Mercury0.1950.078
Silver0.3770.156
Zinc1.3260.546
Gold0.130
Oil and Grease13.00013.000
Total suspended solids19.50015.600
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(b) Silver chloride reduction spent solution.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/troy ounce of silver reduced in solution
Lead0.1120.052
Mercury0.0600.024
Silver0.1160.048
Zinc0.4080.168
Gold0.040
Oil and Grease4.0004.000
Total suspended solids6.0004.800
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(c) Electrolytic cells wet air pollution control.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/troy ounce of gold refined electrolytically
Lead5.5442.574
Mercury2.9701.188
Silver5.7422.376
Zinc20.2008.316
Gold1.980
Oil and Grease198.000198.000
Total suspended solids297.000237.600
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(d) Electrolyte preparation wet air pollution control.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/troy ounce of silver in electrolyte produced
Lead0.0140.007
Mercury0.0080.003
Silver0.0150.006
Zinc0.0510.021
Gold0.005
Oil and Grease0.5000.500
Total suspended solids0.7500.600
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(e) Calciner wet air pollution control.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds) of mercury condensed
Lead6.1602.860
Mercury3.3001.320
Silver6.3802.640
Zinc22.4409.240
Gold2.200
Oil and Grease220.000220.000
Total suspended solids330.000264.000
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(f) Calcine quench water.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds) of mercury condensed
Lead4.9282.288
Mercury2.6401.056
Silver5.1042.112
Zinc17.9507.392
Gold1.760
Oil and Grease176.000176.000
Total suspended solids264.000211.200
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(g) Calciner stack gas contract cooling water.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds) or mercury condensed
Lead1.1620.540
Mercury0.6230.249
Silver1.2040.498
Zinc4.2331.743
Gold0.415
Oil and Grease41.50041.500
Total suspended solids62.25049.800
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(h) Condenser blowdown.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds) of mercury condensed
Lead3.8641.794
Mercury2.0700.828
Silver4.0021.656
Zinc14.0805.796
Gold1.380
Oil and Grease138.000138.000
Total suspended solids207.000165.600
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

(i) Mercury cleaning bath water.

NSPS for the Primary Precious Metals and Mercury Subcategory

Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average
mg/kg (pounds per million pounds) of Mercury condensed
Lead0.3920.182
Mercury0.2100.084
Silver0.4060.168
Zinc1.4280.588
Gold0.140
Oil and Grease14.00014.000
Total suspended solids21.00016.800
pH( 1)( 1)

1 Within the range of 7.5 to 10.0 at all times.

[50 FR 38361, Sept. 20, 1985; 50 FR 41144, Oct. 9, 1985]
authority: Secs. 301, 304 (b), (c), (e), and (g), 306 (b) and (c), 307 (b) and (c), 308 and 501 of the Clean Water Act (the Federal Water Pollution Control Act Amendments of 1972, as amended by the Clean Water Act of 1977) and the Water Quality Act of 1987 (the “Act”); 33 U.S.C. 1311,1314,c,e,and, 1316 (b) andc, 1317 (b) andc,1318; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 101 Stat. 7, Pub. L. 100-4
source: 49 FR 8790, Mar. 8, 1984, unless otherwise noted.
cite as: 40 CFR 421.254
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