EVALUATION OF AIRBORNE CONDUCTIVITY AND VERY LOW FREQUENCY TECHNIQUES AS WATERSHED MANAGEMENT TOOLS SUBJECT: Airborne Conductivity and Very Low Frequency Techniques as Watershed Management Tools DESC: The U.S. Department of Energy's Federal Energy Technology Center (FETC), Pittsburgh, PA intends to award a purchase order on a sole-source basis to the Geoterrex-Dighem's (DIGHEM) to purchase the following services: Statement of Work: FETC has targeted 52 square miles within the Cheat River watershed and approximately 10 square miles of area related to two near-by mine sites for airborne investigations with thermal infrared imagery, conductivity and very low frequency. A map of the 52 square mile area of the Muddy Creek and Roaring Creek watersheds, within the Cheat River watershed, is available in digital form on request. The two small mine sites, Omega and T&T Mines, are located near Morgantown and Albright, WV, respectively. Early November 1999 is targeted for the implementation of this remote sensing work because of the technological need for cold weather, leaf-off conditions and no snow cover.Because of the technological objectives to identify underground mine pools and vertical water-filled fractures (conduits for surface and ground water exchange), and the mountainous topography associated with the targeted survey areas, it is crucial that effective depths of penetration and resolution of data are maximized. FETC has determined that Geoterrex-Dighem's DIGHEMVRES electromagnetic (EM) system with 5 frequencies and coplanar geometry is uniquely capable of meeting the distinctive objectives of this work and provide the greatest opportunity for a successful demonstration. A horizontal coplanar coil orientation is to be used. This work will involve data acquisition by helicopter, such that traverse flight line spacing is to be 100 meters and these lines are not to deviate from the intended flight path by more than one-half of the nominal line spacing over a distance of 1.5 miles. Terrain clearances for the helicopter and instrumentation during normal survey flights are to be maximized, 30 meters or 100 ft is desired. It is recognized, that based on the pilot's judgement of safe flying conditions around man-made structures or in rugged terrain, terrain clearance may vary. The effective depth of penetration of the measured ground penetrating signals are be maximized, such that desired depths should be about 300 feet. It is recognized that geological factors have a significant impact on the effective depths of particular frequencies. The electromagnetic system noise must also be minimized, such that resolution of data is maximized. The detection of underground mine characteristics that may be distinguishable because of the presence of partial or total inundation will require the maximum resolution feasible. The EM system should be calibrated at the start and end of the survey and with an internal coil approximately 3 times per hour during survey flights. Appropriate electronic navigation controls are to be employed, including a GPS system that will determine the absolute position of the helicopter in three dimensions, using orbiting satellites. Post-flight satellite corrections that would result in a positional accuracy of better than 15 feet is required. Since sferic pulses may occur, the EM the data should only be used when their occurrence is less than 5 peaks exceeding 5 ppm per 100 samples over a distance of 1.5 miles. Since VLF data are directionally dependent, two transmitters are to be utilized, one in the northeastern and one in the northwestern United States (e.g., states of Maine and Washington). It is recognized that VLF results may be poor due to weak, irregular or non-existent transmitted fields. However, the scheduling of flights will consider the conventional maintenance times that are generally followed by the military installations. Also, the survey should include the use of a VHS color video camera and cassette recorder operating in the NTSC format, such that the flight path terrain passing beneath the helicopter will be recorded. Time and fiducials are to superimposed on the video recording and can be used to verify the exact flight line location. Finally, all appropriate safety measures should be implemented. DELIVERABLES. Maps at a scale of 1:12,000: Preliminary color conductivity maps for field and office use should be provided as data is collected. Two sets of final color maps including: (1) color conductivity maps for all 5 frequencies, (2) colored filtered VLF maps for the two transmitting stations, and (3) conductivity cross-sections for every 4th line. Contours and flight paths are to be presented on the color maps and X,Y coordinate crosses should appear on all maps. Finally, a topographic base should be prepared such that it appears as grey line-work on the final color maps. 2. Digital Data: All digital data collected on this project should be provided on CD-ROM or 8 mm tape in ER Mapper format, such that FETC will be able to not only duplicate the delivered mapping, but also be provided the opportunity to manipulate and enhance the data. 3. Additional Products: Three copies of a survey report, generated by experienced airborne geophysical analyst, all work related analog chart records and flight path video cassettes should also be provided. This purchase order is being issued to Geoterrex-Dighem because they have developed and manufactured an electromagnetic (EM) resistivity mapping system which uses five coplanar coils at widely separated frequencies (400 Hz, 1600 Hz, 6400 Hz, 25 kHz, and 100 kHz). This system features the greatest frequency range and widest coil separation of any commercially available airborne EM system. Because of the depth of exploration is a function of EM frequency, the wide range of frequencies provides measurements of both shallow and deep geology, and the high number of frequencies provides for detailed sampling within that range of depth. The system is specifically designed to provide the optimum frequency range and resolution for mapping the conductivity of horizontally layered geology with a high degree of accuracy and fine resolution. This award shall be made using simplified acquisition procedures. This is 100% set aside for Small Business. Request for information should be addressed to Mr. Robert L. Mohn, FAX 412-892-6216. E-MAIL: mohn@fetc.doe.gov, mohn@fetc.doe.gov. Posted 09/01/99 (W-SN375471).

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