Code of Federal Regulations Title 40. Protection of Environment 40 CFR Pt. 435, Subpt. A, App. 8 APPENDIX 8 TO SUBPART A OF PART 435—REFERENCE C 16–C 18 INTERNAL OLEFIN DRILLING FLUID FORMULATION

The reference C₁₆–C₁₈ internal olefin drilling fluid used to determine the drilling fluid sediment toxicity ratio and compliance with the BAT sediment toxicity discharge limitation (see § 435.13) and NSPS (see § 435.15) shall be formulated to meet the specifications in Table 1 of this appendix.

Drilling fluid sediment toxicity ratio = 4–day LC₅ of C₁₆–C₁₈ internal olefin drilling fluid/4–day LC₅ of drilling fluid removed from drill cuttings at the solids control equipment as determined by EPA Method 1644:  “Method for Conducting a Sediment Toxicity Test with Leptocheirus plumulosus and Non–Aqueous Drilling Fluids or Synthetic–Based Drilling Muds” after sediment preparation procedures specified in EPA Method 1646, which are published as appendices to Subpart A of this part and in “Analytic Methods for the Oil and Gas Extraction Point Source Category,” EPA–821–R–11–004. See § 435.11(ee) and (uu).