2018-09-14_REVISION - C1981041 - Laserfiche WebLink

Home Browse Search

JAMES A. BECKWITH FONTANARI OBJECTIONS AND COMMENTS / SNOWCAP BOND APPLICATION SL -I I / PG. 2 The Study Area contains valuable basaltic material located to a depth of 50-60 ft. below the surface. The amount of rock (including large boulders) limits the surface use to seasonal livestock grazing and wildlife habitat. Snowcap's Permit and Reclamation Plan acknowledges these established uses of the Study Area. B. SL -11 concerns lands with a history and continuing presence of subsidence. It is well known that, in room -and -pillar mining, the collapse of tunnel roofs due to the removal of pillar support during retreat mining causes surface subsidence. Room -and -pillar mining—including retreat mining—was performed in the Study Area for well over one hundred years.' This occurred in the Old Mine Workings (pre -1980) and New Workings (1980-2000). Collapsed tunnels from both mining eras exist beneath the Study Area. Surface subsidence (tension cracks; voids and depressions) have been present in the Study Area for nearly as long. Mr. Jeff E. Magers of the United States Bureau of Mines first noted tension cracks on Tract No. 70 in 1981-85.2 (Magers Report; Pg. 12; Figs. 10-11) Those cracks merged or evolved into one tension crack 200 feet long and up to 9 feet deep in 1991. (Id.) By 2016, this massive tension crack again evolved into a continuous line of deep, major sinkholes. DRMS' recent August 2018 inspection revealed the continued existence of these sinkholes on Tract No. 70 as well as the presence of new and additional sinkholes in both the northeast corner of Tract No. 70 as well as areas south of the 2016 sinkhole line. It further revealed sinkhole lines along the western wall of the canyon on the tract's eastern border. This latter area has suffered significant slumping in years past, with more current slumping creating a bench 75 feet below the canyon's rim. This slumping is above an area in which, in 1992 Powderhorn Coal Company recorded a lengthy north -south line of collapsed tunnels. (Fontanari Exhibit 2) As another example of the presence of subsidence, on Tract No. 71 surface water migrated through the Old Mine Workings and into the South Portal via surface sinkholes bordering two subsidence depressions in 2014. Inspection of Tract No. 71 in 2016 revealed the continuous existence of these two large depressions, as well as numerous sinkholes bordering the edge of each depression. Those findings were reported to DRMS in October 2016. DRMS' recent August 2018 confirmed the continued presence of both the depressions ' Coal mining beneath Tracts Nos. 70 and 71 began as early as 1888: when J.P. Harlow and George Crawford first obtained a Coal Certificate and U.S. Patent for the southwest corner of Sec. 34, TIOS, R98W. (Fontanari Exhibit 3) Local historians refer to the "Harlow Mine" as the pre -cursor of the "Roadside Mine". The 1980 GEX Mine Map locates the original Harlow Mine adit, or portal, at the north end of this plateau. 2 Surface Subsidence Over A Room -and -Pillar Mine in the Western United States; Jeff A. Magers; United States Department of Interior; 1993 Hereafter, referred to as "Magers Report". A copy of this Report is contained in Tab 10, Snowcap Application.