Hydraulic testing of low-permeability Silurian and Ordovician strata, Michigan Basin, southwestern Ontario

•Hydraulic testing of Silurian and Ordovician sediments – eastern Michigan Basin.•Test equipment, methods and analysis specifically adapted for low-permeability rock.•Parameter perturbation analysis method allows quantification of uncertainty.•K values range from 4E−14 to 4E−8m/s (Silurian) and 2E−16 to 2E−10 m/s (Ordovician).•Scaled Ordovician K values consistent with laboratory and natural analog estimates. Straddle-packer hydraulic testing was performed in 31 Silurian intervals and 66 Ordovician intervals in six deep boreholes at the Bruce nuclear site, located near Tiverton, Ontario, as part of site-characterization activities for a proposed deep geologic repository (DGR) for low- and intermediate-level radioactive waste. The straddle-packer assembly incorporated a hydraulic piston to initiate in situ pulse tests within low hydraulic conductivity (