{"data":{"id":"us/40-cfr-appendix-8-to-subpart-a-of-part-435","jurisdiction":"us","citation":"40 CFR Appendix 8 to Subpart A of Part 435","heading":"Appendix 8 to Subpart A of Part 435—Reference C16-C18 Internal Olefin Drilling Fluid Formulation","body":"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.\nDrilling 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).\nTable 1—Properties for Reference C16-C18 IOs SBF Used in Discharge Sediment Toxicity Testing\nMud weight of SBF discharged with cuttings (pounds per gallon) Reference C16-C18 IOs SBF (pounds per gallon) Reference C16-C18 IOs SBF synthetic to water ratio (%)\n8.5-11 9.0 75/25\n\u003e11-14 11.5 80/20\n\u003e14 14.5 85/15\nPlastic Viscosity (PV), centipoise (cP) 12-30\nYield Point (YP), pounds/100 sq. ft 10-20\n10-second gel, pounds/100 sq. ft 8-15\n10-minute gel, pounds/100 sq. ft 12-30\nElectrical stability, V \u003e300","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER N—EFFLUENT GUIDELINES AND STANDARDS","PART 435—OIL AND GAS EXTRACTION POINT SOURCE CATEGORY","Subpart A—Offshore Subcategory"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"140c3f93b78e2200bee562b4b3700088507f810e92dc75fc9f03fadb50047f3b","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-appendix-7-to-subpart-a-of-part-435","next":"us/40-cfr-435.30"},"notice":"GroundRules: Original legal text. Not legal advice."}