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<br />• 7ur first viSiL to tie Site t0 ODServe oOnsLruCtiOn 'Nds mdde On ~~idrCn 25, <br />.932. ~t thdL time, the ContraCtOr (?dllsade ~~OnStrUCtlOn~ 'Nds In the <br />7rOCesS Of removing LOps0i1 dnd organic mdLter from the waste bank area. <br />'legetation Nas predominately present in the northern one-Half of the pile <br />area with little vegetation present in t'ne south. ?'notograpn 1 attdcneo <br />with this letter shows some of the northern one-half of the pile area <br />before topsoil removal. Topsoil stripped was stockpiled as directed oy <br />empire 3nergy immediately north of the waste bank ared. Pwo•ponds whi m <br />were present in the southeastern portion of the project, 'oelow the plannee <br />toe of the Naste bank were being eewdtared for organic removal dnd <br />bac:.filling. ?hotograph 2 shows the ponds before dewatering. <br />During dewatering of the ponds, a smaii seep was noticed near the bottom of <br />the eastern most pond, adjacent b the eastern embankment. It is believea <br />that the ponds 'were built by excavating nano and gravel soils present in <br />this general area and bottoming the ponds in bedrock. We have been <br />informed that the bedrock in this area dips slightly downward to the west, <br />towards the pond area. It is possible that precipitation infiltrates Lne <br />soils upslope of the ponds and flows along the surface of relatively <br />impermeable bedrock towards the disposal area. We believe that con- <br />struction of the ponds provided an outlet for ground water resulting in the <br />seepage observed. <br />• Because the seep will be beneath the coal processing waste bank, we <br />recommended the installation of a independent subsurface drainage system it <br />accordance with Section 4.09.1 (13) of the MLRB regulations. The <br />independent subsurface drain was constructed by excavating about a 5 foot <br />diameter pit near the seepage area and filling the excavation with free <br />draining gravel. The pit extended about 5 feet below the oottom of the <br />pond, well into bedrock. A 30+ inch wide trench was excavated from the pit <br />to a point of positive gravity discharge, south of the waste bank. A fl- <br />inch diameter PVC pipe was placed in the bottom of the trench from the <br />spring area to the discharge point. The drain pipe was encased in free <br />draining gravel and the trench filled to the ground surface with gravel <br />within the pile area. Within the pile limits, perforated drain pipe was <br />used in the trench. Beyond the pile limits, the pipe trench was backfilled <br />using previously excavated materials and unperforated pipe used. <br />Photograph 3 shows the subsurface drain after gravel placement, prior to <br />backr"filling of the ponds. The drain system has been discharging water <br />since installation. It appears that the quantity of flow is decreasing <br />with time. <br />Once the ponds had been dewatered, all loose and organic soils were <br />removed. The ponds were filled using granular soils and clays borrowed <br />from elsewhere within the planned waste bank area. Backfill was placed oy <br />dozing the material into the ponds and compacting the materials using a 315 <br />• compactor. Photograph 4 shows the ponds after bac:<filling. <br />` During the pond backfilling process, removal of topsoil and snaping of the <br />pile foundation area was continuing. Once the ground surface along the <br />