Means and method of soil water desorption

An apparatus for soil desorption procedures comprising:

• a tubular cylinder;
• top and bottom plates secured over opposite open ends of the cylinder;
• sealing gaskets between the top and bottom plates and the opposite open ends of the cylinder;
• means connected between the top and bottom plates to hold the plates in compression to the cylinder;
• a plurality of holes in the bottom plate aligned with one of the open ends of the cylinder;
• a thin nylon membrane means positionable between the holes in the bottom plate and the cylinder, the nylon membrane means providing low impedance, high rate water flow while maintaining sufficient pressure differentials for soil desorption over a wide range of pressures;
• a channel through the top plate for communication of a high pressure source to the cylinder;
• valve means for opening and closing the channel;
• and
• collection means operatively attachable to the apparatus beneath the bottom plate for collecting desorped liquid, the collection means including means to maintain the collection means at atmospheric pressure.

An apparatus for soil desorption procedures comprising:

• a pressure cell adapted to hold a soil sample containing sorbed water;
• pressurized air supply manifold in fluid communication between a pressurized air source and the pressure cell;
• liquid collection means positioned beneath the pressure cell for collecting any water passing from the pressure cell, the liquid collection means including means for maintaining the liquid collection means at atmospheric pressure;
• pressure regulation means for regulation of air pressure to the supply manifold;
• valve means for independently opening and closing the fluid communication of the manifold to the pressure cell;
• pressure monitoring means for continuously detecting the pressure int he manifold;
• the pressure cell including a hollow cylinder into which can be placed a soil sample, means to secure top and bottom plates over opposite open ends of the cylinder, a plurality of apertures through the bottom plate, elastomeric gasket means to providing a fluid seal between the top and bottom plates and opposite ends of the cylinder, and a thin nylon membrane between the soil sample and the apertures of the bottom plate.

A method of soil desorption comprising in the steps of:

• hydrating a soil sample;
• placing the soil sample in abutment with a thin nylon membrane means for providing low impedance, high rate water flow while maintaining sufficient pressure differentials for soil desorption over a wide range of pressures in a substantially sealed container;
• creating a superatmospheric pressure potential between the soil sample and the side of the nylon membrane opposite to the side abutting the soil sample, where the superatmospheric pressure potential is created between the container holding the soil sample and the opposite side of the nylon membrane which is at atmospheric pressure;
• increasing the high pressure potential to urge any free water in or around the soil sample out of the soil sample and through the nylon membrane;
• increasing the high pressure potential incrementally for adsorbed and absorbed water in the soil sample from the soil sample through the membrane;
• correlating the amount of water forced through the membrane to the corresponding high pressure potential.