REP38413

• Permit No: M1999002
• IBM Index Class Name: Report
• Doc Date: 6/22/2000
• Doc Name: Characterization Report
• From: American Soda LLP
• To: DMG
• Media Type: D
• Archive: No

June 20, 2000 /'age 9
would be difficult to establish with this method and more suitable geophysical techniques exist
(Naeva Geophysics Inc.-Tom I-Iogg and Colorado School of Mines-Dr. Thomas Davis). Also,
there are no guarantees that introducing magnetic material into the cavern will be successful, cost
effective, or even permissible.
4.8 Tiltmeters
"Tiltmeters are high-precision instruments which can measure ground movements as small
as .00] inch (Applied Geomechanics-Jeff Skyler). The instrument actually measures changes in
resistance of a partially fluid electrical circuit. A gas bubble in the conductive fluid is assumed to
orient itself perpendicular to a vertical line and any movement of the bubble will be detected as a
change in electrical resistance.
Tiltmeters have been used successfully in the oil industry for characterization ofthe extents
of hydraulic fracturing (Pinnacle Technology). Tiltmeters are reported to achieve a resolution of
about 100 ftat depths around 2000 ft (Pinnacle Technology-Brie Davis). Combined with computer
model ing, tiltmeter information can produce reasonable estimates ofthe geometry of an underground
reservoir/fracture system. A tiltmeter survey with computer modeling would cost about $30,000,
with a monthly monitoring charge of $3,500 to $4,500 (Pinnacle Technology Eric Davis).
Tiltmeters are well suited for subsidence monitoring of solution mines, but are unlikely to provide
the desired resolution for this application of cavern shape characterization.
S.O REFERENCES
Berest, P. (1986). A Simple Method for Gvalua/ing the Volume of Underground Cavities. Solution
Mining Research Institute.
Bureau of Land Management (1999). Final Tnvironmentallmpac[Statement, Yankee Gulch Sodium
Minerals Project, American Soda, L.L.P. U.S. Department of the Interior.
Cook, .l. C. (1974). Yes, GVe Ccrn Locale Solution Cavity l3omrdaries. 4'"International Symposium
on Salt, Northern Ohio Geological Society.
Dorbin, M. B. (197b). Introduction to Geophysical Prospecting.
Agapito Associates, Inc.