Laserfiche WebLink
Fall 2015 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mininq Areas <br />Figure 5. Southeastward view of a subsidence crack (inside yellow oval) at the top <br />of a cut slope at Location I. <br />3.12.2 Location 4 <br />Subsidence cracks previously noted on the MVB E4-16 pad were again observed during our fall <br />2015 field visit. As noted in previous reports regarding this location, these cracks are pronounced <br />because of a brittle sandstone layer a few feet below this pad. As has been observed in other <br />portions of the mining area, subsidence cracks in a brittle sandstone will weather with time (i.e., <br />crack edges will round and cracks will fill with sediment) but remain observable much longer than <br />subsidence cracks in soils or geologic formations with more plastic features like claystone. Fall <br />2015 observations found these cracks to be more rounded at the top, and widening due to <br />deterioration (cracking and collapse) of the crack walls. Photographs of the cracks on this pad <br />taken during the spring 2014 and fall 2015 field visits are provided for comparison purposes in <br />Figures 6 and 7. <br />831-032.797 Wright Water Engineers, Inc. Page 14 <br />March 2016 <br />