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Matthew S. Hayes <br />June 28, 1989 <br />Page 14 <br />"B Amendments to the F Seam Mine Plan" <br />Three additional monuments will be installed, one at approximately S max above <br />the 1S and 3S panels and the Northwest submain, prior to retreat mining. <br />Exhibit S-1 shows the proposed location of the monuments. These monuments <br />will be surveyed once, one yeaz prior to the anticipated start of retreat mining. <br />One survey will be completed each year until subsidence is complete. Subsidence <br />will be considered complete when two successive years of data show no move- <br />ment other than that attributable to surficial settling, survey error, or other <br />reasons. Exhibit S-1 should be placed with the Upper Water Pile designs in <br />Appendix C-1, Volume II. <br />Stipulation Number 1 to the Mt. Gunnison Mining and Reclamation Plan has <br />been complied with by submittal of an adjudicated plan of augmentation for the <br />unlikely event of measurable water loss caused by subsidence in the Minnesota <br />Creek Basin in this technical revision. <br />Additionally WECC has submitted extensive analysis of F seam subsidence data <br />and interpretations, Bseam geotechnical information, and B seam subsidence <br />predictions as stipulation in No. 19. <br />WECC is unaware of other stipulations or conditions which would not allow <br />subsidence to occur by angle of draw or otherwise in the Minnesota Creek Basin <br />(except 50% extraction limitations under certain creeks), although from a mine <br />planning standpoint, pillars in the East submain will not be pulled during the <br />current 5 year permit therm. Long term plans will likely include additional <br />panels permitted south of the East submain (also south of the drainage divide). <br />No subsidence will occur south of the drainage divide during this permit term. <br />Any plans to subside south of the drainage divide will be addressed by an ap- <br />propriate revision to the permit. <br />"C Subsidence Evaluation and Control Plan" <br />No areas proposed to be subsided in the B seam in the current permit area <br />underlie any azeas which were previously deemed as requiring special protection. <br />