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• 2.05.6(6) <br />A detailed subsidence study for Terror Creek Reservoir dam will be <br />completed prior to mining within one mile of the dam which will occur late <br />2002 or early 2003. The study will establish baseline conditions, potential <br />mining-induced seismicity and potential translated effects. Deadlines for the <br />study are as follows: <br />^ August 1, 2001 -Complete the drilling program including installation of piezometers <br />or other down-hole instrumentation. <br />^ October 1, 2001 -Report of the results for the investigation and seismic evaluation <br />of the structure including recommendations for any additional instrumentation. <br />^ December 1, 2001 -Install any additional instrumentation and a report on the final <br />instrumentation plan. <br />^ Gather baseline data before mining proceeds within one mile of the dam. <br />^ Reports are to be submitted to the DMG for review and approval. <br />Experience at the Bowie No. 1 Mine supports the position that springs and <br />ponds will not be damaged by the effects of subsidence. Under similar <br />geologic conditions, the Bowie No. 1 Mine mined under numerous springs <br />and ponds with no reported detrimental effect on any of the resources. <br />During the period from 1980 through 1997, as presented on the following <br />• table, a total of 12 springs and 28 ponds were undermined. Six springs and <br />six ponds were undermined at depths of less than 800 feet of overburden. <br />Yet there was no detrimental effect on any of the springs or ponds. <br />Bowie No. 1 Mine Hydrologic Monitoring Summary <br />"---____ __----- - Overburden Overburden <br />-----"- ---- No. S rin s Ran a No. Ponds Ran e <br />Total Analyzed I 12 250 tt to 1950 ft 28 100 ft - 2200 ft <br />Less than 800' Overburden I 6 250 ft to 750 ft 6 100 ft - 750 ft <br /> <br />Advance Only I 3 400 ft to 700 ft 3 350 ft - 700 ft <br />_____________________________1__________ ______-___-_____ _________ ______________ <br />Secondary Mined i 3 250 ft to 750 ft 3 100 ft - 750 ft <br />Greater than 800' Overburden i 6 900 tt to 1950 ft 22 850 ft - 2200 ft <br />_____________________________1_-________ <br />1 ______________-_ _________ ______________ <br />Advance Only I 5 1400 ft to 1950 ft 12 900 ft - 2200 ft <br />----_-_- <br />Seconda Mined I 1 900 ft 10 850 ft - 1600 ft <br />This data provides significant validity to the Operators position that no <br />subsidence protection will be provided for springs or ponds unless they are <br />a decreed water right and only then if the spring or pond has an overburden <br />• depth of less than 800 feet. <br />PR-04 2.05 - 109 - 02/22/01 <br />