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Lutzky Associates Development. LP - Geotechnical Investigation <br />MACTEC Project 4953-03-2631 <br />September 18,2003 <br />Pile Installation <br />The specification of pile driving criteria for termination of pile driving will depend on the pile <br />hammer used and the characteristics of the pile selected for construction. Once the pile type and <br />pile driving system are selected, wave equation analysis should be performed to evaluate <br />drivability and to develop driving criteria. The final driving criteria should be developed using <br />wave equation analysis incorporating the results of the indicator pile program recommended <br />below. <br />Unless refusal is encountered, driving should not be terminated until blow counts in excess of the <br />number required to develop the allowable pile load are achieved. Refusal may be defined as <br />driving resistance corresponding to 3 times the required blow counts. <br />We recommend that 8 indicator piles be driven at the site to verify the required pile lengths and to <br />evaluate the efficiency of driving systems before production piles are cast or ordered. The <br />indicator piles should be ordered 10 feet longer than the design length to allow for instrumentation <br />and possible variations in the subsurface materials. We will provide proposed locations of <br />indicator piles after the pile foundation plan is finalized. Dynamic measurements during the <br />indicator pile program using a Pile Driving Analyzer (PDA) is recommended on all indicator piles <br />to develop blowcount and refusal criteria required to develop design capacities as well as to <br />evaluate the induced stresses on the piles and the depth of pre-drilling, if required. <br />If pre-drilling is required to maintain induced stresses on piles below acceptable levels, the auger <br />for pre-drilling should have a cross-sectional area no larger than 80% of the cross-sectional area of <br />the pile. <br />6.3 SPREAD-TYPE SHALLOW FOUNDATIONS <br />The proposed Data Center may be supported on shallow, spread-type footings established in <br />undisturbed natural soils or properly compacted fill soil if the anticipated static settlement and . <br />liquefaction-induced settlements can be accommodated. <br />19