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Sonic Drilling Field Standard Operating Procedure SWE-FSOP-302;Revision 0 Ahtna Southwest Environmental Operations • During drilling, track and note changes in the drilling process (e.g., sounds, rotation speed, sudden drops, etc.)that may indicate changes in lithology, material density, etc., and collect representative soil samples as required by the project work plans. • Any observed problems that include significant downtime and their causes are recorded in the FLB/notepad. • Cuttings and fluids containment during drilling should be observed and supervised by the Field Geologist, as per specifications in the project work plans. If any potentially unsafe conditions are evident during the above drilling observations,the Field Geologist (or any onsite person) may suspend drilling operations and take appropriate actions as per the health and safety plan. In the event suspension of drilling activities occur: • The FTL and Safety Representative must be informed of the situation • Appropriate corrective action must be implemented before drilling may be continued • The observed problem, suspension, and actions taken are entered on the FLB/notepad 4.3.3 Boring Log During drilling,the Field Geologist compiles a boring log. Use field form SWE-FFRM-400. It is expected that the log can be compiled from continuous cores or fairly representative cuttings within the core barrel recovered while drilling. Observations of drilling conditions are also entered on the log. If total depth was reached prematurely due to refusal, the cause should be noted on the boring log and the FLB. If a monitoring well is to be installed in the borehole, a Field Geologist must supervise the work following FSOP-601, "Well Installation." 4.4 Borehole Abandonment If the borehole is to be abandoned after completion, the anticipated quantity of grout determined in advance and tracked during placement. Grout consists of a neat cement mixture containing three to five percent bentonite powder to water by weight. The grout is emplaced as a slurry. The type and composition of the grout mixture should be specified in the project work plans or as determined by the Project Geologist. Tremie-grout the borehole from bottom to top through the inside of the casing as it is retracted to ensure the grout level does not fall below the bottom opening of the casing. When the grout has reached the prescribed level (e.g.,ground surface or less if special site restoration is required),allow the grout to settle and cure. Contain any water or fluids displaced by the neat cement and contain IDW. Excess neat cement shall be placed in portable metal bins or equivalent and disposed of as solid IDW after it is allowed to set. After 24 hours, check the grout for settling, add additional grout if necessary. Grouting is complete when the neat cement hardens, and no settlement has occurred. Restore the final surface per the work plan and applicable specifications (e.g., repair asphalt/cement, soil placement). Page 10 of 11