40 C.F.R. § 471.31
Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT).
Cite as 40 C.F.R. § 471.31 (2026)
Except as provided in 40 CFR 125.30-125.32, any existing point source sub- ject to this subpart must achieve the following effluent limitations for the process operations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT): (a) Rolling spent neat oils—subpart C—BPT. There shall be no discharge of process wastewater pollutants. (b) Rolling spent emulsions. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt rolled with emulsions Chromium 0.075 0.031 Nickel 0.327 0.216 Fluoride 10.1 4.49 Oil and grease 3.4 2.04 TSS 6.97 3.32 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (c) Rolling contact cooling water. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt rolled with water Chromium 1.66 0.679 Nickel 7.24 4.79 Fluoride 225 99.6 Oil and grease 75.4 45.3 TSS 155 73.5 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (d) Tube Reducing Spent Lubricant—subpart C—BPT. (1) There shall be no discharge of process wastewater pollutants except as provided under paragraph (d)(2) of this section. (2) Process wastewater pollutants may be discharged, with no allowance for any pollutants discharged, provided the facility owner or operator demonstrates, on the basis of analytical methods set forth in or approved pursuant to 40 CFR part 136, that the concentrations of nitrosamine compounds in the wastewater discharged from the tube reducing process do not exceed 0.050 mg/l of N-nitrosodimethylamine, 0.020 mg/l of N-nitrosodiphenylamine, and 0.020 mg/l of N-nitrosodi-n-propylamine. (3) The demonstration required under paragraph (d)(2) of this section shall be made once per month until the demonstration has been made for all three nitrosamine compounds for six consecutive months, after which time the demonstration may be made once per quarter. If a sample is found to contain any of the foregoing nitrosamine compounds at concentrations greater than those specified in paragraph (d)(2) of this section, the actions described in paragraph (d)(4) of this section shall be taken, and the demonstration required under paragraph (d)(2) of this section shall be made once per month until it has been made for all three nitrosamine compounds for six consecutive months. (4) If sampling results show that any of the foregoing nitrosamine compounds is present in the process wastewater at concentrations greater than those specified in paragraph (d)(2) of this section, the facility owner or operator shall ensure that, within thirty days of receiving written notification of the sampling results, there is no further discharge of tube reducing spent lubricant wastewater until the owner or operator: (i) Performs a subsequent analysis which demonstrates that the concentrations of the foregoing nitrosamine compounds do not exceed the levels specified in paragraph (d)(2) of this section; or (ii) Substitutes a new tube reducing lubricant and thereafter complies with the requirements of paragraph (d)(3) of this section; or (iii) Determines the source of the pollutant whose concentration exceeded the level specified in paragraph (d)(2) of this section and demonstrates to the satisfaction of the NPDES issuing authority that such source has been eliminated. (5) The concentration limits specified in paragraph (d)(2) of this section apply at the point of discharge from the tube reducing process. However, sampling after the tube reducing wastewater has been commingled with other wastewaters is permitted if: (i) Any dilution caused by the other wastewaters is taken into account in determining the appropriate ( i.e. , lower) allowable discharge concentration; and (ii) An analytical method of sufficient sensitivity is used to measure the levels of each of the foregoing nitrosamine compounds in the wastewaters being sampled. (e) Drawing spent neat oils—subpart C—BPT. There shall be no discharge of process wastewater pollutants (f) Drawing spent emulsions. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt drawn with emulsions Chromium 0.042 0.017 Nickel 0.183 0.121 Fluoride 5.68 2.52 Oil and grease 1.91 1.15 TSS 3.91 1.86 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (g) Extrusion spent lubricants—subpart C—BPT. There shall be no discharge of process wastewater pollutants. (h) Extrusion press or solution heat treatment contact cooling water. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt heat treated Chromium 0.037 0.015 Nickel 0.160 0.106 Fluoride 4.95 2.20 Oil and grease 1.67 0.999 TSS 3.41 1.63 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (i) Extrusion press hydraulic fluid leakage. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt extruded Chromium 0.102 0.042 Nickel 0.446 0.295 Fluoride 13.8 6.13 Oil and grease 4.64 2.79 TSS 9.51 4.53 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (j) Forging equipment cleaning wastewater. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt forged Chromium 0.018 0.007 Nickel 0.077 0.051 Fluoride 2.38 1.06 Oil and grease 0.800 0.480 TSS 1.640 0.780 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (k) Forging contact cooling water. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of forged nickel-cobalt cooled with water Chromium 0.209 0.086 Nickel 0.910 0.602 Fluoride 28.2 12.5 Oil and grease 9.48 5.69 TSS 19.5 9.25 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (l) Forging press hydraulic fluid leakage. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt forged Chromium 0.083 0.034 Nickel 0.359 0.238 Fluoride 11.2 4.94 Oil and grease 3.74 2.25 TSS 7.67 3.65 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (m) Forging spent lubricants—subpart C—BPT. There shall be no discharge of process wastewater pollutants. (n) Stationary casting contact cooling water. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt cast with stationary casting methods Chromium 5.33 2.18 Nickel 23.3 15.4 Fluoride 720 320 Oil and grease 242 145 TSS 496 236 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (o) Vacuum melting steam condensate—subpart C—BPT. There shall be no allowance for the discharge of process wastewater pollutants. (p) Metal powder production atomization wastewater. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt metal powder atomized Chromium 1.16 0.472 Nickel 5.03 3.33 Fluoride 156 69.2 Oil and grease 52.4 31.5 TSS 108 51.1 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (q) Annealing and solution heat treatment contact cooling water—subpart C—BPT. There shall be no allowance for the discharge of process wastewater pollutants. (r) Wet air pollution control scrubber blowdown. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt formed Chromium 0.357 0.146 Nickel 1.56 1.03 Fluoride 48.2 21.4 Oil and grease 16.2 9.72 TSS 33.2 15.8 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (s) Surface treatment spent baths. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt surface treated Chromium 0.412 0.169 Nickel 1.80 1.19 Fluoride 55.7 24.7 Oil and grease 18.7 11.2 TSS 38.4 18.3 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (t) Surface treatment rinse. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt surface treated Chromium 10.4 4.25 Nickel 45.3 30.0 Fluoride 1410 623 Oil and grease 472 283 TSS 968 460 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (u) Alkaline cleaning spent baths. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt alkaline cleaned Chromium 0.015 1.52 Nickel 16.2 10.7 Fluoride 502 223 Oil and grease 169 101 TSS 346 165 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (v) Alkaline cleaning rinse. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt alkaline cleaned Chromium 1.03 0.420 Nickel 4.48 2.96 Fluoride 139 61.5 Oil and grease 46.6 28.0 TSS 95.6 45.5 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (w) Molten salt rinse. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt treated with molten salt Chromium 3.72 1.52 Nickel 16.2 10.7 Fluoride 502 223 Oil and grease 169 101 TSS 346 165 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (x) Ammonia rinse. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt treated with ammonia solution Chromium 0.007 0.003 Nickel 0.029 0.019 Fluoride 0.881 0.391 Oil and grease 0.296 0.178 TSS 0.607 0.289 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (y) Sawing or grinding spent emulsions. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt sawed or ground with emulsions Chromium 0.018 0.007 Nickel 0.076 0.050 Fluoride 2.35 1.04 Oil and grease 0.788 0.473 TSS 1.62 0.769 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (z) Sawing or grinding rinse. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of sawed or ground nickel-cobalt rinsed Chromium 0.797 0.326 Nickel 3.48 2.30 Fluoride 108 47.8 Oil and grease 36.2 21.7 TSS 74.2 35.3 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (aa) Steam Cleaning Condensate. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt steam cleaned Chromium 0.013 0.006 Nickel 0.058 0.039 Fluoride 1.79 0.795 Oil and grease 0.602 0.361 TSS 1.24 0.587 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (bb) Hydrostatic tube testing and ultrasonic testing wastewater—subpart C—BPT. There shall be no allowance for the discharge of process wastewater pollutants. (cc) Degreasing spent solvents—subpart C—BPT. There shall be no discharge of process wastewater pollutants. (dd) Dye penetrant testing wastewater. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt tested with dye penetrant method Chromium 0.094 0.039 Nickel 0.409 0.271 Fluoride 12.7 5.63 Oil and grease 4.26 2.56 TSS 8.74 4.16 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (ee) Electrocoating rinse. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt electrocoated Chromium 1.48 0.607 Nickel 6.47 4.28 Fluoride 201 89.0 Oil and grease 67.4 40.5 TSS 138 65.7 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (ff) Miscellaneous wastewater sources. Subpart C—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of nickel-cobalt formed Chromium 0.108 0.044 Nickel 0.473 0.313 Fluoride 14.7 6.50 Oil and grease 4.92 2.95 TSS 10.1 4.80 pH ( 1 ) ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. [50 FR 34270, Aug. 23, 1985; 51 FR 2884, Jan. 22, 1986, as amended at 54 FR 11348, Mar. 17, 1989]
- Cross-references to the CFR
- 40:125.30-125.32