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CITY OF LATHROP 2.3.3 GEOPHYSICAL LOGGING A. Scope -- This item shall consist of conditioning the bore hole and conducting geophysical surveys in the test hole. The geophysical surveys to be run in the test hole are the gamma ray, spontaneous potential, and resistivity surveys. B. Methods 1.The Contractor shall furnish services for logging the test hole. Acceptable geophysical logging service companies are Stewart Logging Services or Pacific Surveys. Borehole geophysical logs, consisting of gamma ray, spontaneous potential (SP) and multiple resistivity, shall be conducted in the test hole. 2.The spontaneous potential survey shall be plotted on a scale of one-inch equal to plus or minus 20 millivolts. The gamma ray survey shall be plotted on a scale of one-inch equal to plus or minus 20 API units. The multiple resistivity survey shall consist of a point resistivity curve and multiple resistivity curves employing 16-inch short normal and 64- inch long normal spacings on a one-inch equal to 20-or 40-ohm scale. All surveys will be plotted on a footage scale of one-inch equal to 20 feet in accordance with the American Petroleum Institute standard. 3. The Contractor is responsible for the integrity of the borehole to assure that the geophysical logging can be successfully conducted. The Contractor shall maintain circulation in the borehole with tools on the bottom of the hole until the logging equipment is on location and prepared to conduct the survey. The logging service company shall obtain a ditch sample of the circulating fluid for calibration of the logs prior to the securing of the circulating pump. Tools shall then be pulled by the Contractor and the logging services immediately commenced. If the logging probe fails to descend to the desired depth, the Contractor, at his/her own expense, shall run the drilling tools to the target depth to recondition the hole. 4. Upon completion of logging operation, the Contractor will deliver four (3) field prints to the Engineer. Three final prints and an electronic ASCII file of the geophysical surveys shall be provided with the final records submittal. The field copies of the electrical log shall be approved by the City before the logging service is released from the site by the Contractor. 2.3.4 TEST HOLE REAMING A. Scope -- This item shall consist of reaming the test holes to the final specified well depth in accordance with the Engineers'design. The drilling and reaming of the borehole will be conducted by the direct rotary drilling method to the depth and diameter specified in the Engineer's design. Drilling fluid properties must conform to those specified in SECTION 2.1.3. LUHDORFF&SCALMANINI CONSULTING ENGINEERS 12