Laserfiche WebLink
Mike Boulay -5- August 19, 2008 <br />CAM: Page 2-27111 and 2-34 were updated and incorrect text replaced with Coal <br />Mine Waste Pile. <br />25. through 31. Items Resolved. <br />32. DRMS: Excavation of the subsoil, as illustrated in Section D-D' will result in <br />the creation of a basin approximately six feet in depth. The occurrence of a <br />sizable precipitation event prior to the basin being completely filled with coal mine <br />waste may result in the collection of water, which could saturate the soils at the <br />floor of the basin, or any coal mine waste that has already been placed within it. <br />Please address the anticipated effect upon the stability of the coal mine <br />waste pile foundation, should such an event occur, or explain what would <br />prevent this scenario from developing (e.g. the permeability of the <br />surrounding in situ soils may be great enough to prevent retention of water <br />in the basin). <br />CAM: In the event of a large precipitation event prior to the basin being <br />completely filled with coal mine waste, the standing water will be pumped out of <br />the excavated area and pumped into the sediment pond. <br />33. Item Resolved. <br />34. DRMS: CAM's response indicates that an additional stability analysis would <br />be conducted after five feet of material had been placed in the coal mine waste <br />pile. Please clarify the intent of this proposal: does it refer to five feet above <br />the surrounding native ground, or to the first five feet placed in the sub- <br />excavated basin shown on Section D-D'. <br />CAM: The intent is to perform another stability analysis after 5 feet total of <br />material is placed in the excavated area in order to get a representative sample <br />of the embankment materials. Text has been added to page 2-271 for clarity. <br />35. DRMS: The Division requested further waste pile design detail to specify <br />how drainage requirements would be maintained during interim stages of waste <br />pile construction (to divert runoff from above the pile and from the pile surface to <br />stabilized drainages off the fill, prevent runoff from being directed over the <br />outslope, and to prevent ponding on the fill). Amended text on page 2-27iii, and <br />notation on amended Figure 2.2-3 (Section D-D') addressed interim grading to <br />avoid runoff over the face and ponding on the surface of the pile. The apparent <br />need for sequential interim ditching (at interface of fill bench and native slope) <br />that would be warranted as pile construction progresses up the slope was not <br />addressed.