§ 423.13 Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable (BAT).
Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this part must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best available technology economically achievable (BAT).
(a) There shall be no discharge of polychlorinated biphenyl compounds such as those commonly used for transformer fluid.
(b)
(1) For any plant with a total rated electric generating capacity of 25 or more megawatts, the quantity of pollutants discharged in once through cooling water from each discharge point shall not exceed the quantity determined by multiplying the flow of once through cooling water from each discharge point times the concentration listed in the following table:
| Pollutant or pollutant property | BAT Effluent Limitations |
|---|---|
| Maximum concentration (mg/l) | |
| Total residual chlorine | 0.20 |
(2) Total residual chlorine may not be discharged from any single generating unit for more than two hours per day unless the discharger demonstrates to the permitting authority that discharge for more than two hours is required for macroinvertebrate control. Simultaneous multi-unit chlorination is permitted.
(c)
(1) For any plant with a total rated generating capacity of less than 25 megawatts, the quantity of pollutants discharged in once through cooling water shall not exceed the quantity determined by multiplying the flow of once through cooling water sources times the concentration listed in the following table:
| Pollutant or pollutant property | BAT effluent limitations | |
|---|---|---|
| Maximum concentration (mg/l) | Average concentration (mg/l) | |
| Free available chlorine | 0.5 | 0.2 |
(2) Neither free available chlorine nor total residual chlorine may be discharged from any unit for more than two hours in any one day and not more than one unit in any plant may discharge free available or total residual chlorine at any one time unless the utility can demonstrate to the Regional Administrator or State, if the State has NPDES permit issuing authority, that the units in a particular location cannot operate at or below this level of chlorination.
(d)
(1) The quantity of pollutants discharged in cooling tower blowdown shall not exceed the quantity determined by multiplying the flow of cooling tower blowdown times the concentration listed below:
| Pollutant or pollutant property | BAT effluent limitations | |
|---|---|---|
| Maximum concentration (mg/l) | Average concentration (mg/l) | |
| Free available chlorine | 0.5 | 0.2 |
| Pollutant or pollutant property | Maximum for any 1 day −(mg/l) | Average of daily values for 30 consecutive days shall not exceed = (mg/l) |
|---|---|---|
| The 126 priority pollutants (Appendix A) contained in chemicals added for cooling tower maintenance, except: | ( 1) | ( 1) |
| Chromium, total | 0.2 | 0.2 |
| Zinc, total | 1.0 | 1.0 |
1 No detectable amount.
(2) Neither free available chlorine nor total residual chlorine may be discharged from any unit for more than two hours in any one day and not more than one unit in any plant may discharge free available or total residual chlorine at any one time unless the utility can demonstrate to the Regional Administrator or State, if the State has NPDES permit issuing authority, that the units in a particular location cannot operate at or below this level of chlorination.
(3) At the permitting authority's discretion, instead of the monitoring specified in 40 CFR 122.11(b) compliance with the limitations for the 126 priority pollutants in paragraph (d)(1) of this section may be determined by engineering calculations which demonstrate that the regulated pollutants are not detectable in the final discharge by the analytical methods in 40 CFR part 136.
(e) The quantity of pollutants discharged in chemical metal cleaning wastes shall not exceed the quantity determined by multiplying the flow of chemical metal cleaning wastes times the concentration listed in the following table:
| Pollutant or pollutant property | BAT effluent limitations | |
|---|---|---|
| Maximum for any 1 day (mg/l) | Average of daily values for 30 consecutive days shall not exceed −(mg/l) | |
| Copper, total | 1.0 | 1.0 |
| Iron, total | 1.0 | 1.0 |
(f) [Reserved—Nonchemical Metal Cleaning Wastes].
(g)
(1)
(i) FGD wastewater. Except for those discharges to which paragraph (g)(2) or (g)(3) of this section applies, the quantity of pollutants in FGD wastewater shall not exceed the quantity determined by multiplying the flow of FGD wastewater times the concentration listed in the table 1 following this paragraph (g)(1)(i). Dischargers must meet the effluent limitations for FGD wastewater in this paragraph by a date determined by the permitting authority that is as soon as possible beginning October 13, 2021, but no later than December 31, 2025. These effluent limitations apply to the discharge of FGD wastewater generated on and after the date determined by the permitting authority for meeting the effluent limitations, as specified in this paragraph.
Table 5 to Paragraph (g)(1)(i)
| Pollutant or pollutant property | BAT effluent limitations | |
|---|---|---|
| Maximum for any 1 day | Average of daily values for 30 consecutive days shall not exceed | |
| Arsenic, total (ug/L) | 18 | 8 |
| Mercury, total (ng/L) | 103 | 34 |
| Selenium, total (ug/L) | 70 | 29 |
| Nitrate/nitrite as N (mg/L) | 4 | 3 |
(ii) For FGD wastewater generated before the date determined by the permitting authority, as specified in paragraph (g)(1)(i), the quantity of pollutants discharged in FGD wastewater shall not exceed the quantity determined by multiplying the flow of FGD wastewater times the concentration listed for TSS in § 423.12(b)(11).