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operations in order to determine the method of compaction needed to <br />obtain the required density. Once the required procedure for compac- <br />tion is determined and implemented, the fill materials should be tested <br />periodically to determine that the proper density is being achieved. <br />The consideration of underdrains for the pile has been previously <br />addressed by others. Basically, the drains will be placed in natural <br />drainages beneath the pile, and will be protected with a drainage <br />filter fabric such as Mirafi 140-5, Typar Style 3401, or equivalent. <br />This type of drainage system should be suitable. However, care should <br />be taken to maintain proper outfall of underdrains, and care should <br />also be taken that tk.e fabric material is properly installed, A <br />representative from the fabric manufacturer should be consulted with <br />regard to fabric installation. In addition to the subdrains, the <br />coarse, alluvial material existing above bedrock will probably assist <br />in subsurface drainage to a degree. <br />As has been previously mentioned in this report, the area beneath <br />the site has been subject to subsurface mining in the past. The <br />question of mine subsidence has been addressed b~- others, and their <br />reports should be consulted for further information. Generally, the <br />previous reports indicate that material should be brought up evenly <br />across the pile and underdrains be provided with deep outfalls to mini- <br />mize problems associated w.th subsidence. Thc: benches shown on the <br />plan on Plate No. 2 should facilitate maintenance should minor slope <br />disturbance resulting from subsidence occur. Generally, we would not <br />expect the integrity of the mass of the pile to be jeopardized by <br />potential subsidence. <br />In order to monitor water levels within the pile, we recommend <br />that pneumatic piezometers be installed within the pile as it is being <br />