Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT).

Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject 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 emulsions. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium rolled with emulsions Chromiun 0.033 0.014 Zinc 0.109 0.046 Ammonia 9.95 4.37 Fluoride 4.440 1.97 Oil and grease 1.49 0.895 TSS 3.06 1.46 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (b) Forging spent lubricants—subpart B—BPT. There shall be no discharge of process wastewater pollutants. (c) Forging contact cooling water. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of forged magnesium cooled with water Chromium 1.27 0.520 Zinc 4.22 1.77 Ammonia 385 170 Fluoride 172 76.3 Oil and grease 57.8 34.7 TSS 119 56.4 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (d) Forging equipment cleaning wastewater. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium forged Chromium 0.018 0.007 Zinc 0.059 0.025 Ammonia 5.32 2.34 Fluoride 2.38 1.06 Oil and grease 0.798 0.479 TSS 1.64 0.778 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (e) Direct chill casting contact cooling water. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium cast with direct chill methods Chromium 1.74 0.711 Zinc 5.77 2.41 Ammonia 527 232 Fluoride 235 105 Oil and grease 79.0 47.4 TSS 162 77.1 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (f) Surface treatment spent baths. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium surface treated Chromium 0.205 0.084 Zinc 0.681 0.285 Ammonia 62.1 27.3 Fluoride 27.8 12.3 Oil and grease 9.32 5.59 TSS 19.1 9.09 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (g) Surface treatment rinse. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium surface treated Chromium 8.32 3.4 Zinc 27.6 11.5 Ammonia 2520 1110 Fluoride 1130 499 Oil and grease 378 227 TSS 775 369 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (h) Sawing or grinding spent emulsions. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium sawed or ground Chromium 0.009 0.004 Zinc 0.029 0.012 Ammonia 2.60 1.15 Fluoride 1.16 0.515 Oil and grease 0.390 0.234 TSS 0.800 0.381 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times. (i) Degreasing spent solvents—subpart B—BPT. There shall be no discharge of process wastewater pollutants. (j) Wet air pollution control scrubber blowdown. Subpart B—BPT Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/off-kg (pounds per million off-pounds) of magnesium sanded and repaired or forged Chromium 0.273 0.112 Zinc 0.904 0.378 Ammonia 82.5 36.3 Fluoride 36.9 16.4 Oil and grease 12.4 7.43 TSS 25.4 12.1 pH ( 1 ) 1 Within the range of 7.5 to 10.0 at all times.