Sorptivity and Infiltration

Sorptivity and unsaturated hydraulic conductivity were measured using a mini disk infiltrometer (Meter Group). Dry samples were prepared as loosely as possible using dry pluviation into a consolidometer mold (height = 2.54 cm, diameter = 6.35 cm) and then compressed in a pneumatic consolidation load frame (Gilson HM series) to stresses of 1, 25, and 50 kPa. The stresses were applied by the consolidometer to simulate the application of 0.2-10 ft of overburden to the lightweight ash layer. The samples compressed at 1 kPa were prepared intentionally to simulate ash that had been freshly deposited after a wildfire. The suction rate for the mini disk infiltrometer was set at 2 cm-1. Sample A3 was not measured as there was insufficient quantity of ash to run the analysis. Sorptivity and unsaturated hydraulic conductivity were calculated based on the steady-state infiltration rate measured during testing, after Zhang (1997).