7.8 The following data are for a falling-head permeability test: • Length of the soil sample = 140 mm • Diameter of soil sample = 70 mm • Area of the standpipe = 19.6 mm² • At time t = 0, head difference = 500 mm • At time t = 7 min, head difference = 350 mm a. Determine the hydraulic conductivity of the soil (cm/sec) b. What was the head difference at t = 5 min?

4. A constant-head permeability test was conducted on a soil sample retained inside a cylindrical mould with a length of 40cm and an inner diameter of 18cm. In the test setup, a total of 55cm³ of water was collected during 3 hours and 15 minutes after reaching a constant-head difference of 60cm. a. Calculate the hydraulic conductivity (cm/s) of the soil sample. b. Estimate the type and permeability class of the soil. (Show all working calculations.)

Problem (2) The following data are for a variable head permeability test: Area of soil specimen=1200mm? Length of the soil specimen = 150mm Area of the standpipe = 1.3cm² At time t=0, head difference = 750mm At time t=2min, head difference = 500mm 2 %3D a) Find the hydraulic conductivity of the soil in cm/min.

A cylindrical soil sample with length = 15cm and diameter = 4cm was taken from a site where a groundwater contamination piume was found. The sample was tested in the lab to determine its hydraulic conductivity. A hydraulic gradient of 0.05 was applied across the sample, and a flow rate of 0.025 cm³/sec was measured. Calculate the hydraulic conductivity of the soil sample using Darcy's law.