40 CFR § 421.254 - Standards of performance for new sources.
---
identifier: "/us/cfr/t40/s421.254"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 421.254 - Standards of performance for new sources."
title_number: 40
title_name: "Protection of Environment"
section_number: "421.254"
section_name: "Standards of performance for new sources."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "N"
subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"
part_number: "421"
part_name: "NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
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 (b), (c), (e), and (g), 1316 (b) and (c), 1317 (b) and (c), 1318 and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 101 Stat. 7, Pub. L. 100-4."
regulatory_source: "49 FR 8790, Mar. 8, 1984, unless otherwise noted."
cfr_part: "421"
---
# 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 | |
| Lead | 0.364 | 0.169 |
| Mercury | 0.195 | 0.078 |
| Silver | 0.377 | 0.156 |
| Zinc | 1.326 | 0.546 |
| Gold | 0.130 | |
| Oil and Grease | 13.000 | 13.000 |
| Total suspended solids | 19.500 | 15.600 |
| pH | () | () |
| 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 | |
| Lead | 0.112 | 0.052 |
| Mercury | 0.060 | 0.024 |
| Silver | 0.116 | 0.048 |
| Zinc | 0.408 | 0.168 |
| Gold | 0.040 | |
| Oil and Grease | 4.000 | 4.000 |
| Total suspended solids | 6.000 | 4.800 |
| pH | () | () |
| 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 | |
| Lead | 5.544 | 2.574 |
| Mercury | 2.970 | 1.188 |
| Silver | 5.742 | 2.376 |
| Zinc | 20.200 | 8.316 |
| Gold | 1.980 | |
| Oil and Grease | 198.000 | 198.000 |
| Total suspended solids | 297.000 | 237.600 |
| pH | () | () |
| 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 | |
| Lead | 0.014 | 0.007 |
| Mercury | 0.008 | 0.003 |
| Silver | 0.015 | 0.006 |
| Zinc | 0.051 | 0.021 |
| Gold | 0.005 | |
| Oil and Grease | 0.500 | 0.500 |
| Total suspended solids | 0.750 | 0.600 |
| pH | () | () |
| 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 | |
| Lead | 6.160 | 2.860 |
| Mercury | 3.300 | 1.320 |
| Silver | 6.380 | 2.640 |
| Zinc | 22.440 | 9.240 |
| Gold | 2.200 | |
| Oil and Grease | 220.000 | 220.000 |
| Total suspended solids | 330.000 | 264.000 |
| pH | () | () |
| 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 | |
| Lead | 4.928 | 2.288 |
| Mercury | 2.640 | 1.056 |
| Silver | 5.104 | 2.112 |
| Zinc | 17.950 | 7.392 |
| Gold | 1.760 | |
| Oil and Grease | 176.000 | 176.000 |
| Total suspended solids | 264.000 | 211.200 |
| pH | () | () |
| 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 | |
| Lead | 1.162 | 0.540 |
| Mercury | 0.623 | 0.249 |
| Silver | 1.204 | 0.498 |
| Zinc | 4.233 | 1.743 |
| Gold | 0.415 | |
| Oil and Grease | 41.500 | 41.500 |
| Total suspended solids | 62.250 | 49.800 |
| pH | () | () |
| 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 | |
| Lead | 3.864 | 1.794 |
| Mercury | 2.070 | 0.828 |
| Silver | 4.002 | 1.656 |
| Zinc | 14.080 | 5.796 |
| Gold | 1.380 | |
| Oil and Grease | 138.000 | 138.000 |
| Total suspended solids | 207.000 | 165.600 |
| pH | () | () |
| 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 | |
| Lead | 0.392 | 0.182 |
| Mercury | 0.210 | 0.084 |
| Silver | 0.406 | 0.168 |
| Zinc | 1.428 | 0.588 |
| Gold | 0.140 | |
| Oil and Grease | 14.000 | 14.000 |
| Total suspended solids | 21.000 | 16.800 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
[50 FR 38361, Sept. 20, 1985; 50 FR 41144, Oct. 9, 1985]