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Mud Rotary Drilling Field Standard Operating Procedure SWE-FSOP-304;Revision 0 Ahtna Southwest Environmental Operations string. The Field Geologist supervises sampling. Soil samples can be readily obtained at discrete intervals with these methods. Observations of drilling conditions are also entered on the log. If total depth was reached prematurely due to refusal,the cause of refusal should be noted on the boring log and the FLB. 4.3.4 Geophysical Testing Geophysical testing may be conducted at any depth by interrupting the advancement of the drill bit, cleaning the borehole of cuttings, stopping mud circulation, and removing the drill-rod column from the borehole. Borehole geophysical tests may be run at various depths before completing the well. The Field Geologist should note the type(s) of tests run, logging conditions, distribution of log copies and originals, and any observed problems in the FLB/notepad or field form. 4.4 Borehole Abandonment If the borehole is to be abandoned after completion, expected quantities of grout to be used should be calculated 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. Tremie-grout the borehole from bottom to top and through the inside of the casing as it is retracted. Ensure that 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 as 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 has hardened and no settlement has occurred. Restore the final surface per the work plan and applicable specifications (e.g., repair asphalt/cement, soil placement). If a monitoring well is installed in the borehole, the Field Geologist supervises activities following FSOP- 601, "Well Installation." 4.5 Demobilization/Site Restoration After drilling, sampling, well installation, or borehole abandonment is completed, the drill rod, bit, and tools should be laid down, the mast lowered, and the rig moved off the location. The Field Geologist or appropriate designee supervises demobilization/site restoration activities. All debris generated by the drilling operation should be disposed of appropriately. The site should be cleaned,the ground washed as necessary, and the site conditions restored as per the project work plans. All abandoned borings should be topped off and completed per the project work plans. All monitoring Page 10 of 11