The USACE prepared a Supplemental Draft EIS to evaluate an alternative to the Applicant’s Preferred Alternative involving installation of a replacement pipeline segment under the bed of the Straits of Mackinac by horizontal directional drilling (HDD) (the HDD Installation Alternative). The HDD Installation Alternative was evaluated in USACE’s May 2025 Draft EIS but considered infeasible, based on a 2018 Enbridge report, and therefore eliminated from detailed analysis in the EIS. USACE subsequently received information indicating that the HDD Installation Alternative is now feasible due to advances in technology since the 2018 report. USACE determined that the HDD installation Alternative meets the screening criteria established in its May 2025 Draft EIS and therefore will be carried forward for detailed analysis in the EIS.
Enbridge Line 5 Tunnel Project Supplemental Draft Environmental Impact Statement (Executive Summary)