40 CFR § 421.264 - Standards of performance for new sources.
---
identifier: "/us/cfr/t40/s421.264"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 421.264 - Standards of performance for new sources."
title_number: 40
title_name: "Protection of Environment"
section_number: "421.264"
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"
---
# 421.264 Standards of performance for new sources.
Any new source subject to this subpart shall achieve the following new source performance standards:
(a) Furnace wet air pollution control.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of precious metals, including silver, incinerated or smelted | |
| Copper | 5.760 | 2.745 |
| Cyanide (total) | 0.900 | 0.360 |
| Zinc | 4.590 | 1.890 |
| Combined metals | 1.350 | |
| Ammonia (as N) | 599.900 | 263.700 |
| Total suspended solids | 67.500 | 54.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(b) Raw material granulation.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of precious metals in the granulated raw material | |
| Copper | 0.819 | 0.390 |
| Cyanide (total) | 0.128 | 0.051 |
| Zinc | 0.653 | 0.269 |
| Combined metals | 0.192 | |
| Ammonia (as N) | 85.310 | 37.500 |
| Total suspended solids | 9.600 | 7.680 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(c) Spent plating solutions.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/liter of spent plating solution used as a raw material | |
| Copper | 1.280 | 0.610 |
| Cyanide (total) | 0.200 | 0.080 |
| Zinc | 1.020 | 0.420 |
| Combined metals | 0.300 | |
| Ammonia (as N) | 133.300 | 58.600 |
| Total suspended solids | 15.000 | 12.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(d) Spent cyanide stripping solutions.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of gold produced by cyanide stripping | |
| Copper | 4.736 | 2.257 |
| Cyanide (total) | 0.740 | 0.296 |
| Zinc | 3.774 | 1.554 |
| Combined metals | 1.11 | |
| Ammonia (as N) | 493.200 | 216.800 |
| Total suspended solids | 55.500 | 44.400 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(e) Refinery wet air pollution control
<sup>2</sup>.
[^]
<sup>2</sup> This allowance applies to either acid or alkaline wet air pollution control scrubbers. If both acid and alkaline wet air pollution control scrubbers are present in a particular facility the same allowance applies to each.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of precious metals, including silver, produced in refinery | |
| Copper | 1.280 | 0.610 |
| Cyanide (total) | 0.200 | 0.080 |
| Zinc | 1.020 | 0.420 |
| Combined metals | 0.300 | |
| Ammonia (as N) | 133.300 | 58.600 |
| Total suspended solids | 15.000 | 12.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(f) Gold solvent extraction raffinate and wash water.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of gold produced by solvent extraction | |
| Copper | 0.806 | 0.384 |
| Cyanide (total) | 0.126 | 0.050 |
| Zinc | 0.643 | 0.265 |
| Combined metals | 0.189 | |
| Ammonia (as N) | 83.980 | 36.920 |
| Total suspended solids | 9.450 | 7.560 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(g) Gold spent electrolyte.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of gold produced by electrolysis | |
| Copper | 0.011 | 0.005 |
| Cyanide (total) | 0.002 | 0.001 |
| Combined metals | 0.003 | |
| Zinc | 0.009 | 0.004 |
| Ammonia (as N) | 1.160 | 0.510 |
| Total suspended solids | 0.131 | 0.104 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(h) Gold precipitation and filtration.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of gold precipitated | |
| Copper | 5.632 | 2.684 |
| Cyanide (total) | 0.880 | 0.352 |
| Zinc | 4.488 | 1.848 |
| Combined metals | 1.320 | |
| Ammonia (as N) | 586.500 | 257.800 |
| Total suspended solids | 66.00 | 52.800 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(i) Platinum precipitation and filtration.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of platinum precipitated | |
| Copper | 6.656 | 3.172 |
| Cyanide (total) | 1.040 | 0.416 |
| Zinc | 5.304 | 2.184 |
| Combined metals | 1.560 | |
| Ammonia (as N) | 693.200 | 304.700 |
| Total suspended solids | 78.000 | 62.400 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(j) Palladium precipitation and filtration.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of palladium precipitated | |
| Copper | 7.680 | 3.660 |
| Cyanide (total) | 1.200 | 0.480 |
| Zinc | 6.1200 | 2.520 |
| Combined metals | 1.800 | |
| Ammonia (as N) | 799.800 | 351.600 |
| Total suspended solids | 90.000 | 72.000 |
| pH | () | () |
| Within the range of 7.5 to 10.00 at all times. | | |
(k) Other platinum group metals precipitation and filtration.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of other platinum group metals precipitated | |
| Copper | 6.656 | 3.172 |
| Cyanide (total) | 1.040 | 0.416 |
| Zinc | 5.304 | 2.184 |
| Combined metals | 1.560 | |
| Ammonia (as N) | 693.200 | 304.700 |
| Total suspended solids | 78.000 | 62.400 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(l) Spent solution from PGC salt production.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of gold contained in PGC product | |
| Copper | 1.152 | 0.549 |
| Cyanide (total) | 0.180 | 0.072 |
| Zinc | 0.918 | 0.378 |
| Combined metals | 0.270 | |
| Ammonia (as N) | 120.000 | 52.740 |
| Total suspended solids | 13.500 | 10.800 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(m) Equipment and floor wash.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of precious metals, including silver, produced in refinery | |
| Copper | 0.000 | 0.000 |
| Cyanide (total) | 0.000 | 0.000 |
| Zinc | 0.000 | 0.000 |
| Combined metals | 0.000 | |
| Ammonia (as N) | 0.000 | 0.000 |
| Total suspended solids | 0.000 | 0.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
(n) Preliminary treatment.
NSPS for the Secondary Precious Metals Subcategory
| Pollutant or pollutant property | Maximum for any 1 day | Maximum for monthly average |
| --- | --- | --- |
| | mg/troy ounce of total precious metals produced through this operation | |
| Copper | 64.000 | 30.500 |
| Cyanide (Total) | 10.000 | 4.000 |
| Zinc | 51.000 | 21.000 |
| Combined metals | 15.000 | |
| Ammonia (as N) | 6665.000 | 2930.000 |
| Total Suspended Solids | 750.000 | 600.000 |
| pH | () | () |
| Within the range of 7.5 to 10.0 at all times. | | |
[50 FR 38365, Sept. 20, 1985, as amended at 55 FR 31708, Aug. 3, 1990]