2010-03-23_REPORT - C1980007 - Laserfiche WebLink

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Review Checklist for Subsidence Monitoring Report Mine: West Elk Mine Date this review was completed: 3/23/10 Permit No.: C-80-007 CDRMS reviewer: Tom Kaldenbach Report period: Spring 2009 In Monitoring requirement Regulation citation compliance: Comment Yes / no ? Installed and surveyed monuments prior to 2.05.6(6)(c)(i)(A) Yes Prior to 2000, West Elk monitored undermining. subsidence in a monument grid installed Located monuments to over their first three longwall panels. This. detect vertical subsidence 2.05.6(6)I(i)(B) Yes monitoring verified their subsidence and horizontal predictions. From 2000 through Spring displacement. 2007, West Elk conducted an annual visual Monitored each structure's inspection of recently undermined areas orientation, location, 2.05.6(6)1(i)I Yes and previously identified subsidence elevation. features. The frequency of this visual Monitored each monument inspection was increased to semi-annually and structure at least 2.05.6(6)I(i)(D) Yes beginning in Fall 2007. The only quarterly. structures undermined since the previous Commenced monitoring of report (Fall 2009) were USFS roads over each monument and Panel E-1. The monitoring plan requires structure at least one 2.05.6(6)I(i)(D) Yes visual monitoring of undermined roads. month prior to The monitoring plan is consistent with the undermining. existing level of need for verifying the Submitted monitoring subsidence prediction, as required by report at least 2.05.6(6)I(i)(E) Yes 2.05.6(c)(i)(F). semiannually. Conducted sufficient post- mining monitoring to verify subsidence prediction 2.05.6(6I(i))(F) Yes The traverses in the Spring 2009 study included observations of new and previously identified subsidence features. The report describes changes to the previously existing features that have occurred since previous visual inspections. The Spring 2009 report describes the following recent surface subsidence activity: a) continuing rockfall and slabbing in the West Flatiron area, b) subsidence cracks in the mine operator's Box Canyon access road have healed since Accurately predicted 2.05.6(6)(d)(i) Yes the Fall 2008 report, c) rockfall has largely subsidence. ceased on the east side of Sylvester Gulch since the Fall 2008 report, and no subsidence features have been found over the east end of Panel E-1 which recently was longwall mined. These impacts are consistent with the subsidence prediction in the permit application. There was no imminent or actual material damage or 2.05.6(6)(d)(i) Yes diminution of use of