Laserfiche WebLink
Pitch Reclamation Project Colorado Mined Land Reclamation Board — 2013 Annual Reclamation Report <br />Photograph 7: North Pit Lake inlet showing channeling erosion. <br />South Pit: <br />Observations and survey data collected in 2013 indicate that the slope displacement at the east wall of <br />the South Pit has slowed considerably, compared to peak displacement values, but did increase in 2013 <br />relative to the 2011 - 2012 monitoring period. In 2013, slope displacement greater than survey error was <br />observed at nine monuments; HS -4, H -5, MP -92, MP -S8, MP -63, S -1, MP -91, MP -11 and MP -S12. <br />Displacement ranged from 0.03ft/yr to 0.37ft/yr. By comparison, maximum displacement in 2010 was <br />0.72ft/year and 2.0 ft/year in 2008. Maximum displacement during the 2011 — 2012 monitoring period was <br />0.1 Oft/yr. <br />Thirteen monuments were added in 2005 to monitor any slope movement on the east wall of the South <br />Pit. Eight additional survey monuments were installed on the slope by Northstar Surveying, Inc. <br />( Northstar) in October, 2010. The monitoring point locations were selected to replace some of the <br />monuments that had been comprised by slope displacement, and to provide a profile of the entire section <br />of the east wall. This resulted in a net gain of two monitoring points. Some of the monuments that had <br />been compromised were no longer located in key positions, and were abandoned without replacement. <br />Monuments that were abandoned include; S -2, S -4, F -1, F -2, HS -2, and HS -3. <br />The tension cracks and scarps were graded closed in October 2010. In 2011, the bench that transects the <br />displacement was graded with a central crown to promote drainage in both directions of the bench. It was <br />noted in the 2011 report that the displacement appeared to have slowed. Photograph 8 shows the area at <br />the north end of the bench where vertical offset had been observed in 2010. As shown on photograph 9 <br />no significant cracking was present during the 2013 observations and vegetation is beginning to establish. <br />Photograph 10 shows the drainage ditch constructed in 2012 and reseeded in 2013. The repairs work <br />Pitch 2013 Reclamation Report 14April2014.Docx 8 <br />