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ATTACHMENT B CRITERIA FOR AUGER ( CASTJN -PLACE) PILE INSTALLATION The flighting of the auger used to fornl the piles should have a constant diameter that achieves the specified cross -section, and should be continuous from the auger head to tip . The center hole of the auger through which the grout is pumped should have a diameter of at least 3 inches . The auger head used to drive the flighting should have a minimum static weight of 4,000 pounds. It should be powered by a drive unit with at least 150 horsepower and a minimum rated torque of 9 ,000 foot-polmds . The piling leads should be prevented from rotating by a stabilizing arm attached to the crane or by firm embedment of the pile leads in the surficial soils . A positive displacement pump capable of developing a displacement pressure greater that 350 psi should be used to transport the grout to the augered hole . The pump should be provided with a gauge for monitoring pressure and a digital counter for measuring total grout volume. Each pile should be augered and grouted in an uninterrupted sequence. Once the design penetration depth is reached, the auger should be withdrawn 0 . 5 to 1 foot while maintaining positive rotation. This position should be maintained until grout flow has reached the tip at which time the auger should be lowered into the bottom of the hole . The rate of grout injection and auger withdrawal should be closely coordinated so that apositive gauge pressure is maintained at all times . A minimum head of 5 feet of grout should be provided above the auger tip during grouting. The auger should be raised with minimal rotation and with a continuous, steady rate of pull , which allows the required grout head to be maintained. The volume of grout per linear foot of pile should be at least 10 percent larger than that of the neat excavation . In no case should a pile with a grout volume less than the neat excavation volume be accepted. A sequence of pile installation should be used such that previously constructed, adjacent piles are not disturbed. We recommend that new piles not be installed within 6 diameters of freshly grouted piles until the grout in the existing piles has undergone initial set and has been in place at least 6 hours . A.M . Engineering and Testing, Inc .