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Sonic Drilling Field Standard Operating Procedure SWE-FSOP-302;Revision 0 Ahtna Southwest Environmental Operations 4.2.3 Mobilization Once the site is prepared, the rig is mobilized and located over the borehole location. • The drill rig is mobilized to the site and located over the borehole location • The drill rig is leveled with a set of hydraulic pads attached to the front and rear of the drill rig • The driller should always raise the mast slowly and carefully to prevent tipping or damaging the rig and avoid obstructions or hazards 4.3 Drilling Procedures Before drilling, use a hand auger, shovel, or air knife to clear the borehole to the maximum expected depth of any utilities (commonly S feet or greater)to check that underground utilities are not present at the borehole. The driller should be informed of any known shallow subsurface hazards (unidentifiable utility,trapped vapors, etc.). Drilling the surface hole should commence slowly to allow continuous visual inspection and, if necessary, any interruptions for probing until the anticipated maximum depth of any suspected obstructions is exceeded. 4.3.1 Borehole Drilling During drilling operations, and as the borehole is advanced, the Field Geologist will generally: • Observe and monitor rig operations • Conduct all health and safety monitoring and sampling, and supervise health and safety compliance • Prepare a lithologic log from soil samples or cuttings per SWE-FSOP-201, "Soil Classification" • Supervise the collection of, and prepare the soil, soil vapor, and groundwater samples • Soil sampling for volatile organic compounds may require removing (tripping out) the entire inner drill string to collect a representative sample • Groundwater sampling may be performed by retracting the outer casing and allowing water to flow in and be sampled using a bailer or by using a hydropunch-type sampler • For specific soil and groundwater sampling procedures, refer to the project-specific work plans and appropriate FSOP 4.3.2 Ongoing Monitoring The Field Geologist should observe and frequently communicate with the driller regarding drilling conditions as drilling progresses.This includes relative penetration rates(indicative of fast or slow drilling) and chattering or bucking of the rig. • The Field Geologist oversees or conducts appropriate health and safety sampling and monitoring. • The conditions described above, including the relative drilling rate, should be recorded on the boring log. • The Field Geologist should know the total depth of the borehole during drilling. • Drilling should not progress faster than the Field Geologist can adequately observe conditions, compile boring logs, and supervise safety and sampling activities. • The Field Geologist should also observe the rig operations, including the make-up and tightening of connections as sections are added to the drill string. Page 9 of 11