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encountered in trying to pull back casing driven more than <br /> 50 feet. The boring log for LM-60 shows casing to be set to <br /> approximately 106 feet. <br /> • State what procedures will be followed if this <br /> difficulty is encountered. <br /> 9 . According to the boring/well construction log for Well No. <br /> LM-60, it appears that the well may have been drilled <br /> through the Upper Horizon, into the Middle Horizon without <br /> conductor casing to seal the Upper Horizon. <br /> • State what precautions will be taken to prevent <br /> downward migration of the contaminants during well <br /> destruction. <br /> • Again, state whether an in-line filter will be used in <br /> the compressed air line. <br /> • Again, state what type of drilling fluids will be used. <br /> • If potable water and drilling fluids are used, state <br /> that they will be sampled and analyzed for contaminants <br /> of concern prior to use in the drilling operations. <br /> Page 3-2 , Section 3 . 1. 5 <br /> 10. There are two 113 . 1. 5" sections. These comments refer to the <br /> first. The second should be corrected to read 113 . 1 .7 . " <br /> 11. The "downhole" video log would be useful prior to purging <br /> and sampling rather than after, as is proposed in this <br /> section, to establish the integrity of the casing and to <br /> verify the location of the perforations. This would give a <br /> better data base for the implementation of effective purging <br /> and sampling procedures, as well as the decision as to <br /> exactly where to place mill knife perforations prior to <br /> pressure grouting. There is a high probability that the <br /> casing has deteriorated since its emplacement in 1942 , and <br /> the locations of any breaks in the casing could have an <br /> impact on the reliability of the sampling data. <br /> • Explain in the text whether this approach will be used. <br /> Page 3-2 . Section 3 . 1. 6 <br /> 12 . According to Aller (1991) , the cement grout sealant used <br /> must be free of contaminants and must minimize chemical <br /> alteration of the natural groundwater. <br /> • State in the text that the proposed cement grout will <br /> be compatible with the natural groundwater quality. <br /> 4 of 12 <br />