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What is the Unsaturated Flow Apparatus or UFA? AN INNOVATIVE TECHNOLOGY FOR MEASURING TRANSPORT IN SOIL AND ROCK |
The Unsaturated Flow Apparatus or UFATM is an innovative hydrogeochemical instrument for rapidly, directly and accurately determining the fluid transport properties of almost any porous media, such as soil, rock, cement, grout, ceramic or sludge, with respect to almost any fluid, including water, waste effluent, oils and organic solvents. The most important transport properties that require measurement are the hydraulic conductivity of liquids and gases (or the intrinsic permeability of the porous media), diffusion coefficients, the retardation factor or chemical behavior of migrating contaminants, and the composition of the pore fluids. Traditionally, these are very difficult to measure in relatively impermeable materials or under unsaturated conditions. But the UFA directly measures these in hours to days.
The UFA achieves steady-state in hours in cores of any porous media by using an adjustable, whole-body driving force together with precision fluid flow. The instrument consists of an ultracentrifuge with an ultralow pump that provides fluid to the sample through a rotating seal assembly (See Figure). The UFA can attain accelerations up to 20,000 g (soils are generally run up to 1,000 g), temperatures from -20° to 150°C, and non-pulsating flow rates as low as 0.001 ml/h. Effluent is collected in a transparent, volumetrically-calibrated chamber. Samples can be run as recomposites or as in situ samples subcored directly into the UFA sample chamber. Cores of whole rock, ceramic, grout, and other solids are cast in an appropriate resin sleeve.
Because of the large driving forces, steady-state is reached within hours even at hydraulic conductivities as low as 10-10 cm/s, removing the traditional time barrier to these types of experiments. With rapid, direct, accurate measurements of transport properties possible for any porous media, the UFA can address issues facing expedited response actions, screening tests of formulations and material properties, and other problems needing immediate answers.
Click here to read the Cost/Saving Analyses prepared by the Office of Technology Development for using the UFA.
Click here to see a Cost Comparison between using the UFA or the services of UFA Ventures and using Baseline Methods such as Soil Columns or Curve Fitting.
©1996-08 UFA Ventures Inc.
