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| Environmental Technology Listing |
Title of Listing: | | EMFLUX Soil-Gas Detection System |
Category: | | Characterization Technologies |
Subcategory: | * | Air, All Listings |
Media: | | Soil Gas, LNAPL, Groundwater |
Contaminants: | | Halogenated and Non-Halogenated Volatiles, Non-Halogenated Semivolatiles, PNAs, Solvents, Organic Acids, BTEX |
Web Site: | | http://www.mbay.net/~fmasmus/quadrel |
Email: | | quadrel@erols.com |
Technology Description: | |
Quadrel's EMFLUX Soil-Gas System is a fully operational, passive, surface-placed investigative technology capable of identifying buried volatile and semivolatile organic compounds at concentrations in the low parts-per-billion range.
EMFLUX is unique in exploiting -- through a predictive computer model -- the crustal effects of gravity (generally referred to as "earth tides"). These geophysical forces dominate vertical soil-gas velocities, increasing them by three-to-five orders of magnitude. The ability to predict such velocity changes (which dwarf influences of barometric pressure, temperature, moisture, and other phenomena) allows EMFLUX to take advantage of maximum gas emissions at ground surface through simultaneous, cumulative sampling, thereby greatly enhancing detection accuracy and survey reliability. As a result, EMFLUX survey results are reproducible in excess of 90% of the time in terms of both (i) correct identification of individual volatile and semivolatile organic compounds and (ii) proportional duplication at ground surface of changes in subsurface concentrations of targeted compounds.
Field work is simple. Deployment, by individuals or, in some cases, by two-person teams, takes less than two minutes per point (exclusive of initial sample-location survey); retrieval requires half that time; and collectors remain in the field for 72 hours. Field components of the system (9-inch stainless steel shells used above ground; 3.5-inch glass vials or 8-inch copper tubes for shallow subsurface placement) are completely portable. Analytic components range from van-housed mobile laboratories to transportable gas chromatographs.
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Performance Status/
Limitations: | |
Performance Status:
As of August 1996, EMFLUX had been used on some 250 major projects in 34 states and Canada. EMFLUX has been successfully employed to locate a broad spectrum of subsurface volatile and semivolatile toxins, including halogenated compounds, aliphatic and aromatic hydrocarbons, methane, etc. In representative projects the system has detected VOC/SVOC and/or methane contamination at NPL (Superfund) sites; Army, Air Force, Navy, and Marine Corps bases; five national laboratories; EPA emergency removal sites; industrial properties (including manufactured-gas plants); dry-cleaning establishments, paint shops, truck maintenance facilities, and other commercial sites; and sanitary and mixed waste landfills. The system functions in desert heat and freezing temperatures; on rocky and frozen ground, in mud, and under water; over clay lenses and above caliche layers.
Limitations:
By definition, the EMFLUX Soil-Gas System is not reliable in detecting subsurface contaminants which, under ordinary conditions, do not have a vapor phase -- e.g., heavy metals -- or those located beneath an impermeable barrier. In addition, the effectiveness of the technology is reduced for compounds which preferentially adhere to soil or other materials -- e.g., PCBs and pesticides. And finally, the utility of EMFLUX with regard to semivolatile compounds (SVOCs), like that of any other soil-gas system, is directly related to the volatility of the substance in question and inversely related to the sensitivity of the system employed; therefore, given the EMFLUX technology's superior sensitivity, the method performs well over an unusually broad range of SVOCs.
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Topics
Technologies, Characterization
Additional Topics/Tags/Keywords
VOCs, Passive, Monitor, Subsurface, Soil Gas |
Organization: | | Quadrel Services, Inc. |
Address: | | 1896 Urbana Pike
Suite 20 | Phone: | Description | Number |
City: | | Clarksburg | | Primary | (301) 874-5510 |
State/Province/Territory: | | MD | 2. | | |
Zip/Postal Code: | | 20871 | 3. | | |
Country: | | United States | 4. | Fax: | (301) 874-5567 |
Branch Locations: | |
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