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field copies will be approved by the supervising geologist before the logging service is released from the site. 2 . 2 .4 Abandonment of the Corehole Upon completion, the corehole must be grouted to ground surface utilizing tremie techniques. The grout will be tremied from the bottom of the hole upward to displace the drilling fluids in the borehole. The grout may be prepared on-site by the contractor or subcontracted to a local cement service company. 2 . 2 .5 Contractor's Evaluation Upon completion of the corehole, the Contractor shall present a written report to the supervising geologist providing his recommen- dations for satisfactory completion of the well necessary to meet these specifications and the required guarantees. The report shall include the sieve analyses of the formation samples, the screened interval recommended by the Contractor, the screen slot sizes selected by the Contractor based on the character and sieve analyses of the formation samples, and the type and grading of the sand or gravel pack that the Contractor has selected for the well . 2 .2 . 6 Conductor Casing A conductor casing of at least sixteen inches (1611) in diameter will be required if reverse circulation drilling methods are selected. The conductor casing will be set in a hole not less than twenty-two inches (2211) in diameter. It shall be securely anchored at the ground surface to prevent movement. It is estimated that the conductor casing will be set at a depth of twenty feet (201 ) ; however, a greater depth may be found to be advisable during conductor bore drilling. After the conductor casing has been installed, it shall be sealed by filling the annular space between the reamed bore and the conductor casing, with a neat cement grout slurry with five percent bentonite. The placing of the cement shall be done in a manner such that the conductor casing is entirely sealed against infiltra- tion of water. The Contractor shall secure approval of the supervising geologist for the method of grout placement he proposes to use. Upon completion of grouting, cement shall be visible above the surface of the ground outside the conductor casing. After cementing operations are completed, the cement shall be left undisturbed for a period of not less than 24 hours. 2 . 2 . 7 Casing and Screen Components in each well shall include casing and screen installed to an approximate depth of 210 feet. The casing shall be new, low carbon steel pipe, 8 . 625 in. outside diameter, Schedule 20, with a minimum wall thickness of . 250 in. and weight 22 . 36 lbs/ft. The casing shall extend 1. 5 feet above the ground surface. 2 - 3