40 C.F.R. § 435 app 8 to Subpart A of Part 435
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) .
Table 1-Properties for Reference C16-C18 IOs SBF Used in Discharge Sediment Toxicity Testing
| Mud 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 (%) |
| 8.5-11 | 9.0 | 75/25 |
| [GREATER THAN]11-14 | 11.5 | 80/20 |
| [GREATER THAN]14 | 14.5 | 85/15 |
| Plastic Viscosity (PV), centipoise (cP) | 12-30 | |
| Yield Point (YP), pounds/100 sq. ft | 10-20 | |
| 10-second gel, pounds/100 sq. ft | 8-15 | |
| 10-minute gel, pounds/100 sq. ft | 12-30 | |
| Electrical stability, V | [GREATER THAN]300 |
40 C.F.R. 435 app 8 to Subpart A of Part 435