Results of ice-stream models that treat temperate ice deformation as a two-phase flow are sensitive to the ice permeability. We have constructed and begun using a custom, falling-head permeameter for measuring the permeability of temperate, polycrystalline ice. Chilled water is passed through an ice disk that is kept at the pressure-melting temperature while the rate of head decrease indicates the permeability. Fluorescein dye in the water allows water-vein geometry to be studied using fluorescence microscopy. Water flow over durations of seconds to hours is Darcian, and for grain diameter d increasing from 1.7 to 8.9 mm, average permeability decreases from 2 × 10−12 to 4 × 10−15 m2. In tests with dye on fine (d = 2 mm) and coarse (d = 7 mm) ice, average area-weighted vein radii are nearly equal, 41 and 34 μm, respectively. These average radii, if included in a theory slightly modified from Nye and Frank (1973), yield permeability values within a factor of 2.0 of best-fit values based on regression of the data. Permeability values depend on d−3.4, rather than d−2 as predicted by models if vein radii are considered independent of d. In future experiments, the dependence of permeability on liquid water content will be measured.

Laboratory experiments with compacted kaolinite-bentonite mixtures indicate that degradation of hydraulically transported clay lumps in a dredge pipeline can be predicted and controlled to some extent. The size reduction of these lumps depends not only on the length of the pipeline but also on the density of the clay being dredged, the plasticity index (PI) of the clay, and the velocity of the dragging slurry in the pipe. A series of graphs shows percent reduction in clay lumps as a function of PI and velocity at three levels of relative compacted density. If the relationships obtained in this study are shown to be valid in the field, this information will be useful in selecting dredging equipment, designing dredged material containment area, and estimating costs. Relatively undisturbed specimens of the in situ clay and simple laboratory tests would provide the necessary information.