40 CFR § 421.124 - Standards of performance for new sources.

---
identifier: "/us/cfr/t40/s421.124"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 421.124 - Standards of performance for new sources."
title_number: 40
title_name: "Protection of Environment"
section_number: "421.124"
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"
---


# 421.124 Standards of performance for new sources.

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

(a) Subpart L—Film Stripping.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver from film stripping |  |
| Copper | 64.450 | 30.720 |
| Zinc | 51.360 | 21.150 |
| Ammonia (as N) | 6,712.000 | 2,951.000 |
| Total suspended solids | 755.300 | 604.200 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(b) Subpart L—Film Stripping Wet Air Pollution Control and Precipitation and Filtration of Film Stripping Solutions Wet Air Pollution Control.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver from precipitation and filtration of film stripping solutions |  |
| Copper | 1.242 | .592 |
| Zinc | .990 | .408 |
| Ammonia (as N) | 129.300 | 56.840 |
| Total suspended solids | 14.550 | 11.640 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(c) Subpart L—Precipitation and Filtration of Film Stripping Solutions.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver precipitated |  |
| Copper | 73.690 | 35.120 |
| Zinc | 58.720 | 24.180 |
| Ammonia (as N) | 7,674.000 | 3,374.000 |
| Total suspended solids | 863.600 | 690.900 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(d) Subpart L—Precipitation and Filtration of Photographic Solutions.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver precipitated |  |
| Copper | 34.048 | 16.226 |
| Zinc | 27.132 | 11.172 |
| Ammonia (as N) | 3,545.000 | 1,559.000 |
| Total suspended solids | 399.000 | 319.200 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(e) Subpart L—Precipitation and Filtration of Photographic Solutions Wet Air Pollution Control.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver from precipitation and filtration of photographic solutions |  |
| Copper | 15.540 | 7.406 |
| Zinc | 12.380 | 5.099 |
| Ammonia (as N) | 1,618.000 | 711.400 |
| Total suspended solids | 182.100 | 145.700 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(f) Subpart L—Electrolytic Refining.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver from electrolytic refining |  |
| Copper | .973 | .464 |
| Zinc | .775 | .319 |
| Ammonia (as N) | 101.300 | 44.540 |
| Total suspended solids | 11.400 | 9.120 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(g) Subpart L—Furnace Wet Air Pollution Control.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver roasted, smelted, or dried |  |
| Copper | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(h) Subpart L—Leaching.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver produced from leaching |  |
| Copper | .110 | .053 |
| Zinc | .088 | .036 |
| Ammonia (as N) | 11.470 | 5.040 |
| Total suspended solids | 1.290 | 1.032 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(i) Subpart L—Leaching Wet Air Pollution Control and Precipitation of Nonphotographic Solutions Wet Air Pollution Control.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver produced from leaching or silver precipitated |  |
| Copper | 5.671 | 2.703 |
| Zinc | 4.519 | 1.861 |
| Ammonia (as N) | 590.500 | 259.600 |
| Total suspended solids | 66.450 | 53.160 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(j) Subpart L—Precipitation and Filtration of Nonphotograhic Solutions.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver precipitated |  |
| Copper | 3.930 | 1.873 |
| Zinc | 3.132 | 1.290 |
| Ammonia (as N) | 409.300 | 179.900 |
| Total suspended solids | 46.050 | 36.840 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

(k) Subpart L—Floor and Equipment Washdown.

NSPS

| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
|  | mg/troy ounce of silver production |  |
| Copper | .000 | .000 |
| Zinc | .000 | .000 |
| Ammonia (as N) | .000 | .000 |
| Total suspended solids | .000 | .000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. |  |  |

[49 FR 8821, Mar. 8, 1984, as amended at 49 FR 29795, July 24, 1984]