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3 _3 DRILLING <br />3.3.1 Tvpes of Drillin}a <br />,kt Tcapp@r \tine ttterw are three types Of drilling: blast hole erillid;g, exP2o<-a- <br />tion grilling and development drilling. Blast hole cirtlling oscvrs only rizkia <br />the p@rmi_t srea and Ls tegVirad For the blasting operation. The holes a1 -e meeaed <br />tot AacQm&ht of 0xplosive% to fragme%C oVezburgen„ ihterbut-dep a)�j coa2. Roles <br />sizes, depths and spacing% vary a¢cordigg to the and naz,)rg of the <br />material to be blasted. Because the holes are drilled just ahead DT, w <br />an adbanciog pit, they are removed by stripj>ing or mining vitl�in Gey --r4) r,un,,hs <br />or Ie%s. For mor@ detail on bla„ting, see Section 3.4. <br />Exploration drilling occur% outside tht permit ares and is re9uire6 rD dete�n nQ <br />the ektent cf the cosl rest. -rues and to provide inf,.)rmation on coal depth, thick- <br />ness and quality, All exploration drilling is co4duQted ih Romhliance w;rb <br />applihable U.S. Bureau of Land Alanagement and Stage of Colorado reSulakiovs and <br />will be handled by separate permits. <br />Development drilling ix required to proWid® delta for planning pit dimensions, <br />sequehcing activities and equipment scheduling- Typically, develupmeat drilling <br />is conducted at Gr hear the projected coal cropline anal tieeco'nomic sttippio8 <br />lijnit ahead at advartcing pitk and whe?e new pits are planned within, the ;permit <br />area. Drilling aspGhs needed to further define the cropline are usually ooly so <br />the coal in question. Depending upon tht informahion obtaYned, drilling tray be <br />cot -,ducted defining khe crnpltne to within 35 feet horizontally, The economic <br />stripping Limit is defi.ned it, mach the same magnet except It is not necessarily <br />located as accurately as the cropline. <br />Prior to stripping, the overhur0en is drllltd and blasted. Overburden drilling <br />and blasting precedes strippi.hg by one to fiVe ;it wi0th4. Before the overburden <br />is drilled and blasted, the topsoil is removed. Topsgil reikoval is codducted <br />dgYing the fair %veathet months of May through October. Therefore, each year's <br />a-za �APRA!'�d <br />DA <br />REVISED fEnD 1 o <br />