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4 Execution4.1 Percussion drilling of borehole section 0–100 min KFM06CThe percussion drilling operations included:• preparations,• mobilization, including lining up the machine and measuring the position,• drilling, measurements, and sampling during drilling,• finishing off work,• data handling,• environmental control.The four first items are treated in the present section (Section 4.1), whereas the last twoactivities, together with the corresponding items for core drilling, are presented in Sections 4.3and 4.4.4.1.1 PreparationsThe preparation stage included the contractor’s service and function control of his equipment.The machinery was obliged to be supplied with fuel, oil and grease exclusively of the typesstated in SKB MD 600.006, see Table 1-1. Finally, the equipment was cleaned in accordancewith the cleaning instruction in SKB MD 600.004, see Table 1-1, for boreholes of SKB chemicaltype.4.1.2 MobilizationMobilization onto and at the site included preparation of the drill site, transport of drillingequipment as well as of sampling pots for soil and drill cuttings, hand tools and other necessaryoutfit. Furthermore, the mobilization included cleaning of all in-the-hole equipment at level twoin accordance with SKB MD 600.004, lining up the machine and final function control.4.1.3 Drilling, measurements and sampling during drillingThe percussion drilling started with drilling through the overburden during simultaneous casingdriving and subsequent gap injection. These activities followed the principles described inSections 3.1 and 3.2. The borehole was drilled and cased with Ø i 310 mm casing to 12.00 m.During pilot drilling fractured and unstable rock occurred and the drilling was interrupted at61.20 m whereafter the entire borehole was cement filled. After setting of the cement, drillingcontinued and the borehole was extended to 100.40 m with the pilot bit.For stabilization of the entire percussion drilled part, the borehole was reamed to 248.7 mmdiameter and 100.35 m length, and a stainless steel Ø i 200 mm casing was then installed to100.12 m lenght.Before installing the casing, the borehole was cleaned from drill cuttings by a “blow out”with the compressor working at maximum capacity during 30 minutes. This also served as ahydraulic capacity test of the borehole, as the recovery of the groundwater table was registered23