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CITY OF LATHROP <br /> 2.3.4 TEST HOLE REAMING <br /> A. Scope -- This item shall consist of reaming the test holes to the final specified well depth in <br /> accordance with the Engineers'design. The drilling and reaming of the borehole will be conducted <br /> by the direct rotary drilling method to the depth and diameter specified in the Engineer's design. <br /> Drilling fluid properties must conform to those specified in SECTION 2.1.3. <br /> B. Methods <br /> 1.The test hole shall be reamed to a minimum diameter of 12.25 inches and a depth a to <br /> be specified in the Engineer's final design. The drilling fluid for the direct rotary drilling <br /> operation shall conform to the specifications in SECTION 2.1.3. The Contractor shall be <br /> responsible to protect the pilot hole from caving. The Contractor shall exercise caution <br /> to ensure that the hole remains straight and plumb during the reaming operations. <br /> 2.The Contractor shall keep records providing the following information: <br /> a) A record of construction activities for each shift. <br /> b) A time drilling log of the test hole recording the time (in minutes) required to <br /> drill down each section of drill pipe. <br /> c)A log of drilling bit types and depths of changes. <br /> d) Record of drilling fluid properties at 4-hour intervals during drilling operations. <br /> The record shall show drilling fluid weights, Marsh Funnel viscosity,sand content, <br /> drilling fluid losses, and any additives used. <br /> All measurements for depths shall be referenced to the existing ground surface at the well location. <br /> 2.3.5 WELL CASING AND SCREEN <br /> A. Scope -- This item shall consist of furnishing and installing blank casing and well screen as <br /> specified in the City's final design. Conceptual design is included in Figure 2. <br /> B. Methods <br /> 1. A wiper trip shall be conducted to ensure that the borehole is open to the total depth <br /> prior to running casing. <br /> 2. A tremie pipe of a minimum two-inch diameter shall be run into the borehole to the <br /> total depth of the casing installation. Circulation by pumping shall be commenced using <br /> fluid from the drilling fluid/mud tank of the same viscosity as that in the borehole. <br /> Circulation shall continue for a period of sixty minutes prior to casing installation. <br /> LUHDORFF&SCALMANINI <br /> CONSULTING ENGINEERS 13 <br />