40 C.F.R. § 435.43
Except as provided in 40 CFR 125.30-125.32 , any existing point source subject to this subpart must achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best available technology economically achievable (BAT):
BAT Effluent Limitations
| Stream | Pollutant parameter | BAT effluent limitations |
| Produced Water: | ||
| (A) All coastal areas except Cook Inlet | No discharge. | |
| (B) Cook Inlet | Oil & Grease | The maximum for any one day shall not exceed 42 mg/l, and the 30-day average shall not exceed 29 mg/l. |
| Drilling Fluids, Drill Cuttings, and Dewatering Effluent:1 | ||
| (A) All coastal areas except Cook Inlet | No discharge. | |
| (B) Cook Inlet: | ||
| Water-based drilling fluids, drill cuttings, and dewatering effluent | SPP Toxicity | Minimum 96-hour LC50. of the SPP Toxicity Test4 shall be 3% by volume. |
| Free oil | No discharge.2 | |
| Diesel oil | No discharge. | |
| Mercury | 1 mg/kg dry weight maximum in the stock barite. | |
| Cadmium | 3 mg/kg dry weight maximum in the stock barite. | |
| Non-aqueous drilling fluids and dewatering effluent | No discharge. | |
| Drill cuttings associated with non-aqueous drilling fluids | No discharge.5 | |
| Well Treatment, Workover and Completion Fluids: | ||
| (A) All coastal areas except Cook Inlet | No discharge. | |
| (B) Cook Inlet | Oil & Grease | The maximum for any one day shall not exceed 42 mg/l, and the 30-day average shall not exceed 29 mg/l. |
| Produced Sand | No discharge. | |
| Deck Drainage | Free Oil3 | No discharge. |
| Domestic Waste | Foam | No discharge. |
1 BAT limitations for dewatering effluent are applicable prospectively, BAT limitations in this rule are not applicable to discharges of dewatering effluent from reserve pits which as of the effective date of this rule no longer receive drilling fluids and drill cuttings. Limitations on such discharges shall be determined by the NPDES permit issuing authority.
2 As determined by the static sheen test. See § 435.41(ff) .
3 As determined by the presence of a film or sheen upon or a discoloration of the surface of the receiving water (visual sheen).
4 As determined by the suspended particulate phase (SPP) toxicity test. See § 435.41(ee) .
5 When Cook Inlet operators cannot comply with this no discharge requirement due to technical limitations (see appendix 1 of subpart D of this part), Cook Inlet operators shall meet the same stock limitations (C16-C18 internal olefin) and discharge limitations for drill cuttings associated with non-aqueous drilling fluids for operators in Offshore waters (see§ 435.13 ) in order to discharge drill cuttings associated with non-aqueous drilling fluids.
40 C.F.R. §435.43