Laserfiche WebLink
precipitation and subsequent infiltration, and facilitated contemporaneous reclamation. <br />~Tlte reclamation procedures associated with this mining method consisted of backfilling to approximate original <br />contour, reestablishing surface drainage patterns, replacing topsoil material, contour furrowing, and revegetating. <br />Placement of excavated spoils using a walking dragline was anon-selective placement method. No toxic or acid- <br />forming substances were identified in the overburden, so that related groundwater impacts were not a concern. <br />Recontouring and rough-grading of replaced spoils occurred as soon as practicable after backfilling. Rough- <br />grading activities resulted in an undulating surface and some subsurface compaction tended to reduce infiltration <br />over [he roughened spoil condition. Generally, the rough-graded spoils demonstrated a slightly higher infiltration <br />rate than undisturbed areas. <br />Completion of final reclamation activities, including topsoil replacement and revegetation, occurred concurrently <br />with settlement of the replaced spoils. Based upon Colorado Yampa Coal Company's operating experience in the <br />Twentymile Park area, some minimal settlement and compaction [he soil-subsoil-spoil profile was expected to <br />occur on a gradually declining basis with most of the settlement occurring during the initial 3 years following <br />placement. Surface permeability was anticipated to initially exceed the premitting conditions slightly. The <br />+cumulative effect of overburden excavation, spoil placement, and gradual settlement/compaction should provide a <br />more homogeneous mass with a final infiltration rate approaching that of undisturbed overburden materials after <br />several years. <br />Water Ri~h[s <br />Colorado Yainpa/Twentymile Coal Company is the only user having control of registered groundwater rights in <br />the permit and adjacent areas. Colorado Yampa/Twentymile Coal Company's water use is limited primarily to <br />dust control and washdown, so any localized groundwater impacts would not be significant. <br />• <br />1996 Permit Ren. Permit Renewal 780-144-4 Revised 3/18/97 <br />