A municipal landfill utilizes a compacted 1.08-m-thick clay liner that has a hydraulic conductivity of 1 x 10-7 cm/sec. If the depth of the leachate above the clay liner is

30 cm and the porosity of the clay is 55%, the time (years) required for the leachate to migrate through the liner is most nearly: (А) 15; (В) 17; (C) 25; (D) 27