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Environmental Technology Listing
Title of Listing:
DMLS - Passive Multilayer Sampler For Groundwater
Category:
Characterization Technologies
Subcategory:
 *Water, All Listings
Media:
Groundwater
Contaminants:
Halogenated Volatiles and Semivolatiles, Organic pesticides/Herbicides, Gases, Heavy Metals
Web Site:
Email:
dzr@randomc.com
Technology Description:

The DMLS is a Diffusion Multi-Layer Sampler for groundwater. Sampling occurs passively through natural diffusion and therefore, no pumping or other displacement is involved. The DMLS provides a vertical profile of groundwater samples at a resolution of 1 foot or better.

          The DMLS is based on a cell dialysis technique. Dialysis cells are filled with distilled water and covered by semipermeable membranes at both ends. When the cells are exposed to the aquifer water, a diffusion starts which is driven by the gradient of concentration. Water moves from the aquifer into the cell until equilibrium is reached. At equilibrium the cell contents represent the external water.

          Cells are positioned on a rod and separated by seals which fit the inner diameter of the well. The seals stratify the aquifer into layers.

          The DMLS can be left in the well for any period of time (but not less than 10 days). Upon retrieval, cell contents are tested and analytical results provide a vertical profile of the chemical composition of the aquifer water at a resolution of 1 foot or better.

          A vertical profile of the layers' flow rates can be obtained through reverse diffusion of a tracer which is loaded in cells and diffuses into the aquifer water. Determination of the flow rate is accomplished by measuring the end dilution of the tracer in the cell.

          The DMLS is modular. Units can be connected one to another to form any length and the assembled modular units can be lowered to any depth. The DMLS can be a carrier platform for a large variety of cells, analytical traps and in situ measurement devices. Cells for general sampling, for colloidal particle trapping, and for flow rate measurement are already available. Cells with selective trapping capabilities are under development. Cells capable of in situ analytical measurements will be developed in the future.
Performance Status/
Limitations:

Performance Status:

          Since its introduction to the U.S. market in November 94, the DMLS has been successfully installed commercially at 10 sites. DMLS applications include:
          1) Sampling of a deep (>600-foot) reference well used as background for several cleanup projects at a DOE facility (Hanford). Parameters measured: Ions and heavy metals.
          2) Characterization of a DCE plume at a DOD AFB (Clear cut boundaries of the plume and its exact location have been shown).
          3) Characterization of a chromium and organics plume (done by the Robert S. Kerr Laboratory).
          4) Follow-up sampling to optimize a pump-and-treat remediation at a DOE site. Based on the DMLS profile one zone of the well turned out to be clean. More elaborate tests are planned which should lead to reduction of the volume of requiring pump-and-treat for PCE contamination.
          5) Flow rate measurement at a DOE site.
          6) Delineation of an Atrazine plume at a site in Israel and follow-up bioremediation treatability study in which the dialysis cells were used as in situ bacteriological chambers.

          Limitations:

          Presently there are no technological limitations known except the detection limit of the analytical method and DMLS can be used for any groundwater sampling purpose. If needed, pretesting of specific materials easily can be performed in the lab.
Topics
Sample Collection, Technologies, Characterization
Additional Topics/Tags/Keywords
Sampler, Groundwater, Passive

Organization:
Margan M.L.S (1994) Ltd.
Address:
4052B Dunwoody Park
Phone:
DescriptionNumber
City:
Dunwoody
1.
Primary (770) 390-9950
State/Province/Territory:
GA
2.
Zip/Postal Code:
30338
3.
Country:
United States
4.
Fax:(770) 390-0487
Branch Locations: